Microbial contamination and biofilm-forming pathogens in dental unit waterlines: A cross- sectional study of opportunistic bacteria and infection control implications in an urban setting of China

Microbial contamination and biofilm-forming pathogens in dental unit waterlines: A cross- sectional study of opportunistic bacteria and infection control implications in an urban setting of China | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Microbial contamination and biofilm-forming pathogens in dental unit waterlines: A cross- sectional study of opportunistic bacteria and infection control implications in an urban setting of China Yu-ting Li, Qiaoqiao Hu, Fu-qing Chen, Yuxin Qin, Nuodan Wu, Fen Yang, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7419035/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Background Dental unit waterlines (DUWLs) are susceptible to microbial contamination, posing significant infection risks. This study aimed to assess microbial contamination levels, identify biofilm-forming pathogens, and evaluate infection control practices in DUWLs across multi-tier medical institutions. Methods A cross-sectional study was conducted using stratified random sampling of 214 dental chair units (DCU) from 55 medical institutions (16 tertiary, 9 secondary/below-level, and 30 private) in Nanchang, China. DUWLs management data were collected via questionnaires. Water samples were collected from four sites (source water, handpiece, triple-syringe, and rinse water; total n = 2,782) at four time points: pre-operation (0 mL drainage), after 200 mL drainage, and at the end of morning and afternoon sessions. Bacterial counts were cultured on nutrient and Legionella agars, with compliance defined as ≤ 500 CFU/mL. Species identification was performed using MALDI-TOF MS and Sanger sequencing. Biofilm formation was quantified by crystal violet staining (OD₅₇₀ₙₘ). Risk factors were analyzed using generalized estimating equations (GEE). Results Severe DUWLs contamination was observed. Pre-operation compliance rates were 10.75% (handpieces), 17.76% (triple-syringes), and 29.91% (rinse water). Drainage of 200 mL significantly improved compliance (41.59–63.08%). Despite the highest compliance rates observed at the end of sessions (time point 4), 16.82% of handpiece and 19.16% of triple-syringe samples still exceeded the limit. Source water compliance was 46.73%. Tertiary hospitals demonstrated better water quality compared to secondary/private institutions. Multivariate GEE analysis indicated a higher contamination risk in handpieces from secondary/below-level (OR = 2.088, 95% CI: 1.253–3.481, P = 0.005) and private institutions (OR = 1.861, 95% CI: 1.178–2.939, P = 0.008) compared to tertiary hospitals. Regular disinfection was identified as a protective factor (OR = 4.767, 95% CI: 2.321–9.790, P < 0.001).Among 2,123 isolates (60 species), dominant genera included Sphingomonas (447 strains), Bacillus (431), and Acidovorax (320). A total of 383 (18.0%) isolates were identified as strong biofilm formers. Eight opportunistic pathogens were ranked by biofilm-forming capacity (OD₅₇₀ₙₘ) as follows: Staphylococcus xylosus > Bacillus cereus > Staphylococcus warneri > Acidovorax mediterraneus > Pseudomonas otitidis > Acinetobacter baumannii > Pseudomonas aeruginosa > Staphylococcus hominis . Conclusions DUWLs contamination is severe, with biofilm colonization being a core concern. Hospital tier (tertiary vs. non-tertiary) and regular disinfection significantly affect water quality. This study is the first to systematically identify eight strong biofilm-forming opportunistic pathogens in DUWLs, providing a scientific basis for targeted disinfection and optimized waterline management. Urgent interventions—emphasizing effective disinfection and enhanced infection control in primary care—are warranted. Dental unit waterlines Opportunistic pathogens Biofilm Microbial contamination Nosocomial infection Disinfection Figures Figure 1 1. Background Dental unit waterlines (DUWLs) supply treatment water to dental chair unit (DCU), directly feeding clinical instruments such as triple syringes and high-speed handpieces. The microbiological quality of DUWLs is critically linked to patient safety and nosocomial infection risks during oral healthcare procedures[1, 2]. This association has heightened concern among healthcare administrators and public health authorities regarding DUWLs contamination. P Primary contamination sources include source water pollution [3], biofilm colonization of tubing materials [4], microbial retraction through handpieces and triple syringes during operation [5, 6], and intermittent water flow patterns [5, 6]. Substantial contamination levels have been documented globally: Studies in Chongqing reported microbial loads reaching 10²–10⁶ CFU/mL [7, 8], while Tianjin-based research identified peak concentrations of 1.8×10⁶ CFU/mL [6]. Italian clinics demonstrated total viable counts of 8.72×10⁴ CFU/mL with co-isolation of Pseudomonas aeruginosa and Legionella spp. [9]. Alarmingly, compliance rates in Beijing primary-care facilities were merely 6.52% for handpieces and 6.72% for scaler water [10]. DUWLs harbor clinically significant opportunistic pathogens including Bacillus subtilis , P. aeruginosa , Legionella pneumophila , Escherichia coli , Candida albicans , C. glabrata , and C. guilliermondii [5, 11–15]. Contaminated water poses dual transmission risks: direct patient ingestion and aerosol-mediated dispersion during instrument operation. These aerosols pollute operatory air and environmental surfaces [15–17], substantially elevating the potential for healthcare-associated infection (HAI). Consequently, DUWLs represent critical reservoirs for nosocomial pathogen transmission, creating significant infection control challenges. Despite existing research on DUWLs quality determinants [7, 10, 18–20], methodological limitations persist including single timepoint sampling, restricted culture approaches, incomplete microbial profiling, insufficient outlet coverage, and absence of dynamic daily monitoring. To address these gaps, this study implemented a comprehensive assessment protocol featuring multi-phase sampling across four operational intervals, enhanced pathogen identification via MALDI-TOF MS and Sanger sequencing, biofilm quantification through crystal violet assays, and management practice analysis using structured questionnaires. Our integrated approach aims to characterize contamination dynamics across hospital tiers, identify high-risk biofilm-forming pathogens, and formulate evidence-based infection control protocols for dental settings. 2. Methods 2.1 Study Subjects Clinical trial number: not applicable. A total of 214 Dental Chair Units (DCU) from 55 healthcare institutions in Nanchang City were selected using stratified random sampling. This included 16 tertiary Grade A hospitals, 9 secondary Grade A or lower hospitals, and 30 private medical institutions. Samples were collected from DUWLs, including source water, handpiece water, triple-syringe water water, and mouth rinse water. 2.2 Questionnaire Survey A standardized questionnaire was administered by sampling personnel to collect data on: institutional information, DCU configuration, water supply type, DUWLs usage and management practices (including flushing, draining, disinfection protocols, filter replacement frequency, daily patient volume, etc.). 2.3 Water Sample Collection Water samples were collected according to the following protocol: Source water was obtained at the beginning of the clinical day prior to any water discharge. Samples from the handpiece, triple-syringe water, and mouth rinse outlets were collected at four defined time points: Timepoint 1 (T1) at the beginning of the clinical day without discharging water; Timepoint 2 (T2) at the beginning of the clinical day after discharging 200 mL of water; Timepoint 3 (T3) at the conclusion of the morning clinical session; and Timepoint 4 (T4) at the conclusion of the afternoon clinical session. Before handpiece sampling, air pressure was disabled to prevent aerosolization. Strict aseptic technique was followed: hand hygiene was performed prior to sampling, each outlet was disinfected twice with 75% ethanol swabs and air-dried, and 10 mL of water was collected into sterile tubes. All samples were transported to the laboratory within 1 hour of collection. 2.4 Microbiological Testing Testing Samples were vortexed thoroughly, and 50 µL aliquots were spread onto Nutrient Agar (NA) plates (90 mm diameter) incubated at 37°C for 48 hours, and Legionella Selective Agar plates incubated at 37°C with 5.0% CO₂ for 120 hours. Total Bacterial Count (TBC) was determined by enumerating colonies using an automated colony counter after incubation, with compliance defined as TBC ≤ 500 CFU/mL according to the US CDC standard for dental treatment water [150]. Bacterial identification was performed using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS): single colonies were smeared onto a target plate, overlaid with 2 µL of matrix solution A, air-dried, then overlaid with 1.5 µL of matrix solution B, air-dried again, and analyzed by comparing spectra to the reference database. For 16S rRNA gene sequencing, universal primers 27F (5'-AGAGTTTGATCMTGGCTCAG-3') and 1492R (5'-TACGGYTACCTTGTTACGACTT-3') were used for PCR amplification, followed by sequencing and BLASTn analysis against the NCBI database. For strain preservation, single colonies were inoculated into LB broth, incubated overnight at 37°C, mixed with sterile 40% glycerol (800 µL suspension:200 µL glycerol), and stored at -20°C and − 80°C. 2.5 Biofilm Formation Assay (Crystal Violet Staining) Bacterial strains were cultured in LB broth to logarithmic growth phase, diluted 1:100 in fresh LB broth to achieve 1.0 × 10⁶ CFU/mL, and 200 µL aliquots were added to 96-well microtiter plates with sterile LB broth controls. After static incubation at 37°C for 24 hours, the medium was discarded and wells were gently rinsed thrice with sterile PBS. Biofilms were fixed with 200 µL methanol for 15 minutes, rinsed with PBS, air-dried, stained with 200 µL 0.5% (w/v) crystal violet for 15 minutes, rinsed extensively with physiological saline until colorless, air-dried, and solubilized with 200 µL 33.3% (v/v) glacial acetic acid for 5–10 minutes.The optical density (OD) of solubilized dye was measured at 570 nm using a microplate reader. 2.6 Criteria for Biofilm Formation Capacity Biofilm formation capacity was classified based on OD₅₇₀ₙₘ relative to blank control wells (ODc): Non-biofilm former (OD < ODc), Weak (ODc ≤ OD < 2×ODc), Moderate (2×ODc ≤ OD < 4×ODc), or Strong (OD ≥ 4×ODc) [151]. 2.7 Statistical Analysis Data were entered into Excel, cleaned, and analyzed. Descriptive statistics presented normally distributed continuous data as mean ± standard deviation (SD), non-normally distributed data as median (interquartile range) [M (Q1, Q3)], and categorical data as frequency (percentage) [n (%)]. Univariate analyses employed Analysis of Variance (ANOVA) for normal continuous data, Kruskal-Wallis H test for non-normal continuous data, and Chi-square (χ²) test for categorical data. Longitudinal analyses used Repeated Measures ANOVA for normal data or Generalized Estimating Equations (GEE) for non-normal data. Multivariable GEE models (exchangeable correlation matrix) analyzed: 1) TBC (log-transformed if needed) to identify influencing factors, and 2) Handpiece water compliance (binary) status. Statistical significance (α = 0.05) was defined as p < 0.05 using SPSS 26.0, with figures generated in GraphPad Prism 9.5.0. 3. Results 3.1 Configuration and Management Status of DCUs in Healthcare Institutions A total of 214 DCU across 55 institutions were surveyed (Table 1 ). Tertiary Grade A hospital accounted for the highest proportion of DCU (43.46%). Most institutions (67.76%) had > 5 DCU. The majority of DCU (70.56%) had been in service for ≤ 5 years, and 68.69% had a daily patient load of ≤ 5. Central water treatment systems were the predominant water supply method (57.94%). Compliance with recommended practices was suboptimal: DUWLs disinfection (35.05%), filter replacement according to manufacturer instructions (35.98%), and draining waterlines during non-operational hours (45.79%). Hydrogen peroxide (17.76%) and chlorine-based disinfectants (17.29%) were the most commonly used chemical agents for disinfection. Table 1 Configuration and Management Status of DCUs Across Multi-Tier Medical Institutions Variable Category DCU Count (n = 214) Proportion (%) Healthcare Institution Count (n = 55) Proportion (%) Hospital Level Grade III, Level A 93 43.46 16 29.09 Grade II and below 26 12.15 9 16.36 Private 95 44.39 30 54.55 Total Units ≤ 5 69 32.24 28 50.91 >5 145 67.76 27 49.09 Years in Use ≤ 5 151 70.56 — — >5 63 29.44 — — Daily Patient Volume ≤ 5 147 68.69 — — >5 67 31.31 — — Water Supply Type Central water treatment 124 57.94 25 45.45 Municipal tap water 90 42.06 30 54.55 Filter Replacement Per manufacturer's instructions 77 35.98 11 20.00 Never 137 64.02 44 80.00 Clinical Specialty Endodontics/Conservative Dentistry 11 5.14 — — General Dentistry 200 93.46 — — Other specialties 4 1.40 — — DUWLs Flushing Before/after patient 154 71.96 36 65.45 Never 60 28.04 19 34.55 DUWLs Drainage Drain during breaks 98 45.79 35 63.64 Never 116 54.21 20 36.36 DUWLs Disinfection Regularly disinfected 75 35.05 13 23.64 Never 139 64.95 42 76.36 Disinfectant Type Hydrogen peroxide 38 17.76 3 5.45 Chlorine-based disinfectant 37 17.29 10 18.18 None 139 64.95 42 76.36 3.2 Bacterial Counts and Compliance Rates by Sampling Timepoint and Outlet A total of 2,782 water samples were collected (856 handpiece, 856 triple-syringe water, 856 mouth rinse, 214 source water). Bacterial counts differed significantly across timepoints for all outlets ( P < 0.001), demonstrating a significant decrease over time ( P < 0.001) (Tables 2 , 3 ). Timepoint 1 (T1, start of day, no flush) exhibited the most severe contamination, with handpiece water showing the highest median bacterial count (1240 CFU/mL) and the lowest compliance rate (10.75%). Compliance rates improved significantly for all outlets after discharging 200 mL of water (T2). Although Timepoint 4 (T4, end of afternoon) had the highest overall compliance, handpiece (83.18%) and triple-syringe water (80.84%) water still exhibited non-compliance rates of 16.82% and 19.16%, respectively. Source water had a median count of 620 CFU/mL and a compliance rate of 46.73%. Compliance rates consistently followed the trend: handpiece water < triple-syringe Table 2 Bacterial colony counts at different water outlets across sampling periods [CFU/mL, M (Q1, Q3)] Sampling Period Sample Type Median (M) IQR (Q1, Q3) χ² P -value Period 1 Handpiece water 1240 (860,1800) 285.821 <0.001 Triple-syringe water 1080 (680,1560) — — Rinse water 730 (435,1120) — — Period 2 Handpiece water 610 (400,1120) 81.537 <0.001 Triple-syringe water 480 (320,900) — — Rinse water 440 (240,700) — — Period 3 Handpiece water 380 (220,620) 29.297 <0.001 Triple-syringe water 380 (220,570) — — Rinse water 270 (180,420) — — Period 4 Handpiece water 300 (180,460) 21.519 <0.001 Triple-syringe water 320 (200,460) — — Rinse water 220 (100,340) — — Table 3 Bacterial colony counts and pass rates at different water outlets across sampling periods Handpiece Water (n = 856) Triple-syringe Water (n = 856) Rinse Water (n = 856) Source Water (n = 214) Total Samples Median (CFU/mL) IQR (CFU/mL) Compliance Rate (%) Median (CFU/mL) IQR (CFU/mL) Compliance Rate (%) Median (CFU/mL) IQR (CFU/mL) Compliance Rate (%) Median (CFU/mL) IQR (CFU/mL) Compliance Rate (%) 1240 (860,1800) 10.75 1080 (320,900) 17.76 730 (180,420) 29.91 620 (260,940) 46.73 856 610 (680,1560) 41.59 480 (240,700) 51.87 440 (180,460) 63.08 642 380 (435,1120) 68.22 380 (220,620) 72.90 270 (200,460) 84.58 642 300 (400,1120) 83.18 320 (220,570) 80.84 220 (100,340) 93.46 642 water < mouth rinse water (except at T4). 3.3 Factors Influencing Water Sample Compliance 3.3.1 Univariate Analysis Univariate analysis (χ² test) of factors potentially influencing compliance revealed significant associations. Draining DUWLs during non-operational hours was associated with significantly higher handpiece compliance at T1 (16.33% vs 6.03%, P = 0.02) and mouth rinse compliance at T2 (72.45% vs 55.17%, P = 0.01) compared to never draining (Table 4 ). Regular DUWLs disinfection significantly improved handpiece compliance at T1 (17.33% vs 7.19%, P = 0.02) and mouth rinse compliance at T2 (76.00% vs 56.12%, P < 0.001) compared to no disinfection (Table 5 ). Replacing filters per manufacturer instructions significantly improved mouth rinse compliance at T2 (77.92% vs 54.74%, P < 0.001), handpiece compliance at T4 (90.91% vs 78.83%, P = 0.02), and triple-syringe compliance at T3 (81.82% vs 67.88%, P = 0.03) and T4 (88.31% vs 76.64%, P = 0.037) compared to never replacing filters (Table 6 ). DCUs with a daily patient load ≤ 5 had significantly higher handpiece compliance at T4 compared to those with > 5 patients (87.07% vs 74.63%, P = 0.02). Hospital level, number of DCU, unit age, water supply method, and flushing practices did not significantly affect compliance rates ( P > 0.05). Table 4 One-way ANOVA analysis of pass rates at different water outlets across periods by drainage status [n(%)] DUWLs Drainage Practice N * Period 1 N# (Compliance %) Period 2 N# (Compliance %) Period 3 N# (Compliance %) Period 4 N# (Compliance %) Handpiece Syringe Rinse Handpiece Syringe Rinse Handpiece Syringe Rinse Handpiece Syringe Rinse Never drained (n = 1392) 116 7(6.03) 18(15.52) 29(25.00) 48(41.38) 59(50.86) 64(55.17) 75(64.66) 82(70.69) 100(86.21) 92(79.31) 92(79.31) 105(90.52) Drained during breaks (n = 1176) 98 16(16.33) 20(20.41) 35(35.71) 41(41.84) 52(53.06) 71(72.45) 71(72.45) 74(75.51) 81(82.65) 86(87.76) 81(82.65) 95(96.94) χ² 5.87 0.87 2.91 0.01 0.10 6.81 1.49 0.63 0.51 2.71 0.38 3.58 P -value 0.02 0.35 0.09 0.95 0.75 0.01 0.22 0.433 0.4 0.10 0.54 0.06 Table 5 One-way ANOVA analysis of pass rates at different water outlets across periods by disinfection status [n(%)] DUWLs Disinfection Status N * Period 1 Period 2 Period 3 Period 4 Handpiece Syringe Rinse Handpiece Syringe Rinse Handpiece Syringe Rinse Handpiece Syringe Rinse Never disinfected (n = 1668) 139 10(7.19) 21(15.11) 36(25.90) 54(38.85) 69(49.64) 78(56.12) 90(64.75) 98(70.50) 120(86.33) 112(80.58) 109(78.42) 128(92.09) Regular disinfection (n = 900) 75 13(17.33) 17(22.67) 28(37.33) 35(46.67) 42(56.00) 57(76.00) 56(74.67) 58(77.33) 61(81.33) 66(88.00) 64(85.33) 72(96.00) χ² 5.22 1.91 3.04 1.23 0.79 8.27 2.21 1.15 0.93 1.92 1.50 1.22 P -value 0.02 0.17 0.08 0.27 0.37 0.00 0.14 0.28 0.33 0.17 0.22 0.27 Table 6 One-way ANOVA analysis of pass rates at different water outlets across periods by filter replacement status [n(%)] Filter Replacement Practice N* Period 1 Period 2 Period 3 Period 4 Handpiece Syringe Rinse Handpiece Syringe Rinse Handpiece Syringe Rinse Handpiece Syringe Rinse Never replaced (n = 1644) 137 14(10.22) 25(18.25) 37(27.01) 54(39.42) 68(49.64) 75(54.74) 91(66.42) 93(67.88) 119(86.86) 108(78.83) 105(76.64) 126(91.97) Replaced per manufacturer (n = 924) 77 9(11.69) 13(16.88) 27(35.06) 35(45.45) 43(55.84) 60(77.92) 55(71.43) 63(81.82) 62(80.52) 70(90.91) 68(88.31) 74(96.10) χ² 0.11 0.06 1.53 0.74 0.76 11.37 0.57 4.85 1.52 5.14 4.33 1.38 P -value 0.74 0.80 0.22 0.39 0.38 0.00 0.45 0.03 0.22 0.02 0.037 0.24 3.3.2 Multivariate GEE Analysis (Handpiece Water) Multivariate GEE Analysis handpiece water compliance (≤ 500 CFU/mL = compliant, > 500 CFU/mL = non-compliant) as the dependent variable (independent variable coding in Table 7 ). Results (Table 8 ) showed significantly higher odds of non-compliance for handpiece water in secondary Grade A or lower hospitals (OR = 2.088, 95%CI: 1.253–3.481, P = 0.005) and private institutions (OR = 1.861, 95%CI: 1.178–2.939, P = 0.008) compared to tertiary Grade A hospitals. Regular DUWL disinfection was a significant protective factor, associated with substantially lower odds of non-compliance compared to no disinfection (OR = 4.767, 95%CI: 2.321–9.790, P < 0.001). Unit age, daily patient load, total DCUs, water supply method, flushing practices, draining practices, and filter replacement status showed no statistically significant association with handpiece water compliance ( P > 0.05). Table 7 Variable assignment instructions Variable Category Variable Name Coding Scheme Bacterial count in water Y 0 = Compliant (≤ 500 CFU/mL); 1 = Non-compliant (> 500 CFU/mL) Hospital type X1 1 = Grade III Level A; 2 = Grade II and below; 3 = Private Years in use X2 1 = ≤ 5 years; 2 = > 5 years Daily patient volume X3 1 = ≤ 5 patients; 2 = > 5 patients Total DCUs X4 1 = ≤ 5 units; 2 = > 5 units Water supply type X5 1 = Central water treatment; 2 = Municipal tap water DUWLs flushing practice X6 1 = Never; 2 = Before/after treatment DUWLs drainage practice X7 1 = Never; 2 = Drain during breaks DUWLs disinfection practice X8 1 = Never; 2 = Regular disinfection Filter replacement practice X9 1 = Per manufacturer instructions; 2 = Never replaced Table 8 Multivariate GEE analysis of factors affecting pass rates in dental handpiece water Variable Category β (SE) 95% CI Wald χ² OR (95% CI) P -value intercept 0.086 (0.264) -0.431 to 0.604 0.107 1.09 (0.65–1.83) 0.743 Hospital level Grade III A (ref) 1 1 Grade II and below 0.736 (0.261) 0.225 to 1.247 7.978 2.09 (1.25–3.48) 0.005 Private 0.621 (0.233) 0.164 to 1.078 7.088 1.86 (1.18–2.94) 0.008 Years in use ≤ 5 (ref) 1 1 > 5 -0.127 (0.217) -0.554 to 0.299 0.343 0.88 (0.58–1.35) 0.558 Daily patient volume ≤ 5 (ref) 1 1 > 5 -0.197 (0.191) -0.570 to 0.177 1.066 0.82 (0.57–1.19) 0.302 Total DCUs ≤ 5 (ref) 1 1 > 5 -0.046 (0.171) -0.381 to 0.289 0.072 0.96 (0.68–1.34) 0.788 Water supply Central treatment (ref) 1 1 Municipal tap water -0.379 (0.194) -0.760 to 0.002 3.805 0.69 (0.47-1.00) 0.051 DUWLs flushing Never (ref) 1 1 Before/after treatment -0.294 (0.227) -0.739 to 0.152 1.672 0.75 (0.48–1.16) 0.196 DUWLs drainage Never (ref) 1 1 Drain during breaks -0.214 (0.234) -0.673 to 0.245 0.834 0.81 (0.51–1.28) 0.361 DUWLs disinfection Never (ref) 1 1 Regular disinfection 1.562 (0.367) 0.842 to 2.281 18.084 4.77 (2.32–9.79) < 0.001 Filter replacement Per manufacturer (ref) 1 1 Never replaced -0.358 (0.262) -0.872 to 0.156 1.862 0.70 (0.42–1.17) 0.172 3.4 Microbial Composition and Biofilm Formation Capacity of DUWLs 3.4.1 Microbial Species Analysis Cultivation identified 60 bacterial species comprising 2,123 isolates. Predominant genera included Sphingomonas (12 species, 447 isolates), Bacillus (9 species, 431 isolates), Acidovorax (7 species, 320 isolates), Staphylococcus (7 species, 182 isolates), Cupriavidus (3 species, 254 isolates), and Pseudomonas (3 species, 108 isolates). Dominant species varied by outlet (Table 9 ). The top three species overall were Bacillus cereus (6.43%), Sphingomonas paucimobilis (6.39%), and Cupriavidus pauculus (6.19%). Table 9 Composition of main microorganisms at different water outlets in DUWLs (%) Bacterial Species Source Water (n = 214) Handpiece Water (n = 856) Triple-syringe Water (n = 856) Rinse Water (n = 856) Total (n = 2782) Bacillus cereus 1.71 6.46 6.88 7.07 6.43 Sphingomonas paucimobilis 23.43 4.98 4.97 5.48 6.39 Cupriavidus pauculus 17.71 5.32 4.08 6.78 6.19 Acidovorax intermedius 6.29 3.85 3.57 6.06 4.53 Micrococcus luteus 5.14 4.98 3.69 4.62 4.5 Bacillus firmus 2.29 5.32 4.33 3.75 4.38 Bacillus paramycoides 0.57 2.83 5.35 5.05 4.06 Bacillus megaterium 3.43 4.42 4.33 3.32 4.02 Acidovorax delafieldii 4.57 4.3 3.31 3.61 3.82 Cupriavidus metallidurans 1.71 3.62 3.82 3.46 3.51 Novosphingobium subterraneum 6.29 3.17 3.82 2.6 3.43 Sphingobium yanoikuyae 7.43 1.7 3.69 3.17 3.12 3.4.2 Biofilm Formation Capacity Crystal violet staining identified 492 isolates (23.2%) with significantly higher biofilm formation than controls (OD₅₇₀ₙₘ >ODc). Among these, 383 (18.0%) were strong biofilm formers (OD₅₇₀ₙₘ ≥ 4×ODc) and 5 (0.2%) were moderate formers (2×ODc ≤ OD₅₇₀ₙₘ Bacillus cereus > Staphylococcus warneri > Acidovorax facilis > Cupriavidus pauculus > Acinetobacter baumannii > Pseudomonas aeruginosa > Staphylococcus hominis (Fig. 1 ). 4. Discussion This systematic investigation comprehensively assessed contamination status and influencing factors within DUWLs in a representative regional cohort. Findings reveal substantial microbial contamination across surveyed healthcare institutions, posing significant nosocomial infection risks. Analysis of 2,782 water samples collected from 214 DCU across 55 multi-tiered institutions—at four critical timepoints (pre-operatory 0mL flush, 200mL flush, end of morning/afternoon sessions)—combined with institutional audits, provides robust evidence on current water quality challenges and their determinants. Water quality exhibited significant temporal variation. Alarmingly low compliance rates were observed at baseline (T1: no flush) for handpiece (10.75%), triple-syringe (17.76%), and mouth rinse (29.91%) outlets. Compliance substantially improved post-200mL discharge (41.59%, 51.87%, 63.08%; P < 0.001), aligning with established evidence [21–23]. While international guidelines recommend flushing DUWLs for 30 seconds to 3 minutes pre-operatively [24–26], persistent non-compliance at session conclusions (e.g., handpiece: 16.82% at T4) demonstrates that flushing alone is insufficient against mature biofilms [1,27–31]. Outlet-specific contamination gradients (handpiece < triple-syringe < mouth rinse) predominantly reflect retraction effects: negative pressure upon instrument deactivation aspirates oral microbiota into waterlines [32,6]. Although anti-retraction valves are recommended [33], their high failure rate (74%) [34]—often linked to inadequate maintenance—necessitates rigorous valve surveillance protocols [30]. Source water contamination (compliance: 46.73%) further compounds risks by introducing environmental microbes directly into treatment systems [8,35], underscoring the imperative for source water control. Tertiary institutions demonstrated superior compliance, attributable to integrated infection prevention infrastructures (resource allocation, organizational protocols, compliance monitoring) [18,19]. Conversely, primary/secondary and private facilities exhibited critical gaps: low protocol awareness, absent standardized procedures, and poor implementation [36,37]. This disparity mandates tiered regulatory oversight, including mentorship programs pairing tertiary centers with resource-limited institutions and competency-based IPC training. Regular chemical disinfection emerged as the most effective intervention for DUWLs contamination control (OR = 4.767, P < 0.001), particularly for managing Mycobacterium colonization [38]. However, suboptimal disinfection adherence globally [39,40] reflects persistent knowledge-practice gaps. Complementary measures—filter replacement per manufacturer guidelines and post-operative waterline drainage—also improved compliance. Filters provide transient protection but require scheduled maintenance to avoid clogging or becoming secondary reservoirs [33]. Low adoption rates (20%) likely stem from technical complexity, vendor dependence, and cost. While drainage reduces stagnation and biofilm formation, its cumbersome execution (~ 2–3 minutes/unit) and lack of automated systems limit uptake (implementation: 63.64%). Multivariable GEE models identified institutional characteristics influencing water quality: DCU clusters (> 5 units) and newer devices (≤ 5 years) correlated with improved compliance, likely reflecting enhanced IPC governance [20]. Lower daily patient volumes (≤ 5) also improved outcomes, potentially due to reduced retraction frequency and cumulative biofilm burden [42]. Water supply systems (central vs. independent), flushing protocols, and device age showed no significant association—possibly confounded by municipal water quality, inconsistent filter maintenance, and biofilm resilience post-maturation [12]. Our analysis of DUWLs reveals a complex ecosystem harboring clinically significant pathogens with critical implications for infection control in dental practice. The microbial profile demonstrates concerning prevalence of opportunistic pathogens and biofilm-forming species, creating dual challenges for waterline maintenance and patient safety. Clinically Significant Pathogens in DUWLs Sphingomonas species emerged as dominant aquatic bacteria in our samples, consistent with reports showing 38% prevalence in purified laboratory water systems [43] and contamination of endoscope rinse water [44]. Particularly problematic is S. paucimobilis (6.39% prevalence), which survives disinfectants and nutrient-poor conditions while demonstrating pan-drug resistance to β-lactams, aztreonam, and polymyxin B [45]. This pathogen accounts for 86.7% of healthcare-associated Sphingomonas infections [46], including hemodialysis-related bloodstream outbreaks [47] and post-cataract endophthalmitis [48], confirming DUWLs as reservoirs for multidrug-resistant organisms. Bacillus cereus (6.43% prevalence) challenges traditional perceptions as merely an environmental contaminant. Our findings align with evidence of its pathogenic potential, causing sepsis and CNS infections [49] across diverse populations (neonates 41%, elderly 26%, adults 23%) with 21% mortality in systemic infections [50]. Notable staphylococcal species include: S. xylosus (2.44%): Associated with persistent endodontic infections [51] S.hominis : Exhibiting alarming resistance (100% penicillin, 82.9% oxacillin) in hematology patients [52] High-priority nosocomial pathogens were also identified in Table 10 . Table 10 Pathogen Prevalence Clinical Concern A. baumannii 0.83% Resistance surge (23%→63%, 2004–2014) [53]; causes complex infections [54] P. aeruginosa Detected 51,000 annual U.S. HAIs; limited therapeutic options [55] C. pauculus 6.19% Fatal respiratory infections in immunocompromised [56] While Legionella was culture-negative in our study – likely due to viable-but-non-culturable (VBNC) states – its detection in other DUWLs studies (0-100%) [57, 58] warrants ongoing vigilance. Biofilm Formation Dynamics and Challenges DUWLs provide ideal biofilm conditions through: 1) persistent moisture/stagnation, 2) nutrient enrichment from oral fluid retraction, 3) bacterial adhesion on polyurethane surfaces, and 4) aggregation in narrow lumens. This facilitates rapid colonization within 8 hours of operation [59]. Biofilms represent complex microbial communities encased in extracellular polymeric substance (EPS) matrices [60]. While prior studies characterized DUWLs biofilm diversity (824 taxa [71]), viability [61], and antibiotic resistance [62], key biofilm-forming species remained unidentified. Using crystal violet semi-quantitative staining, we found 23.2% (492/2,123) of isolates formed biofilms, with 18% (383) exhibiting strong capacity. Eight species demonstrated exceptional biofilm proficiency: B . cereus (disinfectant-resistant biofilms [63]) A. baumannii (> 90% clinical isolates form biofilms [64]) P. aeruginosa (rapid 8-12h adhesion [65]) C. pauculus (outperforms P. aeruginosa in certain conditions [66]) A. intermedius (enhances L. pneumophila colonization [67]) S. Warneri S. Hominis S. Xylosus Of particular concern, A. intermedius promotes colonization of L. pneumophila – associated with 33% pneumonia mortality [68]. Staphylococcal findings align with literature: S. xylosus is the most proficient biofilm-former among coagulase-negative staphylococci [69], while > 50% of S. hominis bloodstream isolates form robust biofilms [70]. 5. Conclusion This study confirms the severity of microbial contamination in DUWLs within clinical settings, identifying critical influencing factors and characterizing the microbiological profile. Significantly, we provide the first systematic identification of key opportunistic pathogens with strong biofilm-forming capacity in DUWLs, including Staphylococcus xylosus , Bacillus cereus , and Staphylococcus warneri . These findings establish a vital theoretical foundation for advanced mechanistic understanding of DUWLs contamination dynamics, development of targeted and safe disinfection strategies against core biofilm-forming species, and evidence-based optimization of waterline management protocols. Collectively, these insights deliver actionable guidance for mitigating DUWLs contamination and preventing dental care-associated nosocomial infections, emphasizing the imperative for enhanced disinfection protocols—particularly in resource-limited settings. Declarations Acknowledgements Not applicable Authors’ contributions Na Li initiated the research concept and contributed to study design. Fuqing Chen, Qiaoqiao Hu and Fen Yang performed data acquisition and partial experimental procedures. Yuxin Qin, Jing Guo and Nuodan Wu carried out data analysis and statistical interpretation. Yuting Li participated in manuscript preparation. All authors critically reviewed and approved the final version of the manuscript. Funding This work was supported by the National Natural Science Fund of China [grant number: 82460192]. Availability of data and materials The 16S rRNA gene sequences generated during this study have been deposited in the NCBI GenBank database under the accession number range PX365876 to PX365917. These records are currently undergoing the final release processing by NCBI and will become fully accessible at the following URL shortly: https://www.ncbi.nlm.nih.gov/nuccore/PX365876. The accession numbers are guaranteed and can be verified as assigned by contacting [email protected] with the submission ID SUB15638281. Ethics approval and consent to participate This study was conducted in accordance with the Declaration of Helsinki and approved by the ethics committee of The First Affiliated Hospital of Nanchang University, Nanchang, China. Written informed consent was obtained from all participants. Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests References O'Donnell MJ, Shore AC, Russell RJ, et al. Optimisation of the long-term efficacy of dental chair waterline disinfection by the identification and rectification of factors associated with waterline disinfection failure. J Dent. 2007;35(5):438-51. https://doi.org/10.1016/j.jdent.2007.01.001 Hahn MW. The microbial diversity of inland waters. Curr Opin Biotechnol. 2006;17(3):256-61. https://doi.org/10.1016/j.copbio.2006.05.006 Mills SE. The dental unit waterline controversy: defusing the myths, defining the solutions. 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Distinct Microbial Community of Accumulated Biofilm in Dental Unit Waterlines of Different Specialties. Front Cell Infect Microbiol. 2021;11:670211. https://doi.org/10.3389/fcimb.2021.670211 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 13 Mar, 2026 Reviews received at journal 22 Oct, 2025 Reviews received at journal 16 Oct, 2025 Reviewers agreed at journal 13 Oct, 2025 Reviewers agreed at journal 08 Oct, 2025 Reviewers invited by journal 08 Oct, 2025 Editor assigned by journal 08 Oct, 2025 Editor invited by journal 30 Sep, 2025 Submission checks completed at journal 29 Sep, 2025 First submitted to journal 28 Sep, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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03:03:27","extension":"html","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":162846,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7419035/v1/261ff6b7a2b9893054f8b70a.html"},{"id":94054987,"identity":"83f63eff-391f-4c5d-83b7-059789cabe4f","added_by":"auto","created_at":"2025-10-22 03:03:27","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":131460,"visible":true,"origin":"","legend":"\u003cp\u003eBiofilm formation ability (OD570nm value) of different microorganisms. The bar chart illustrates the optical density (OD) values of eight bacterial strains, ranked in descending order as follows: \u003cem\u003eStaphylococcus xylosus\u003c/em\u003e \u0026gt; \u003cem\u003eBacillus\u003c/em\u003e \u003cem\u003ecereus\u003c/em\u003e \u0026gt; \u003cem\u003eStaphylococcus\u003c/em\u003e \u003cem\u003ewarneri\u003c/em\u003e \u0026gt; \u003cem\u003eAcidovorax\u003c/em\u003e \u003cem\u003etemperans\u003c/em\u003e\u0026gt; \u003cem\u003eCupriavidus\u003c/em\u003e \u003cem\u003epauculus\u003c/em\u003e \u0026gt; \u003cem\u003eAcinetobacter\u003c/em\u003e \u003cem\u003ebaumannii\u003c/em\u003e\u0026gt; \u003cem\u003ePseudomonas\u003c/em\u003e \u003cem\u003eaeruginosa\u003c/em\u003e \u0026gt; \u003cem\u003eStaphylococcus\u003c/em\u003e \u003cem\u003ehominis\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7419035/v1/256e2327845208e616df2c31.jpeg"},{"id":94055531,"identity":"ab050de1-f8a7-43f3-9276-56e3e40695f2","added_by":"auto","created_at":"2025-10-22 03:27:28","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1917853,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7419035/v1/806abfde-2cc0-4fd7-bb68-8212c007efce.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Microbial contamination and biofilm-forming pathogens in dental unit waterlines: A cross- sectional study of opportunistic bacteria and infection control implications in an urban setting of China","fulltext":[{"header":"1. Background","content":"\u003cp\u003eDental unit waterlines (DUWLs) supply treatment water to dental chair unit (DCU), directly feeding clinical instruments such as triple syringes and high-speed handpieces. The microbiological quality of DUWLs is critically linked to patient safety and nosocomial infection risks during oral healthcare procedures[1, 2]. This association has heightened concern among healthcare administrators and public health authorities regarding DUWLs contamination. P Primary contamination sources include source water pollution [3], biofilm colonization of tubing materials [4], microbial retraction through handpieces and triple syringes during operation [5, 6], and intermittent water flow patterns [5, 6].\u003c/p\u003e\u003cp\u003eSubstantial contamination levels have been documented globally: Studies in Chongqing reported microbial loads reaching 10\u0026sup2;\u0026ndash;10⁶ CFU/mL [7, 8], while Tianjin-based research identified peak concentrations of 1.8\u0026times;10⁶ CFU/mL [6]. Italian clinics demonstrated total viable counts of 8.72\u0026times;10⁴ CFU/mL with co-isolation of \u003cem\u003ePseudomonas aeruginosa\u003c/em\u003e and \u003cem\u003eLegionella\u003c/em\u003e spp. [9]. Alarmingly, compliance rates in Beijing primary-care facilities were merely 6.52% for handpieces and 6.72% for scaler water [10]. DUWLs harbor clinically significant opportunistic pathogens including \u003cem\u003eBacillus subtilis\u003c/em\u003e, \u003cem\u003eP. aeruginosa\u003c/em\u003e, \u003cem\u003eLegionella pneumophila\u003c/em\u003e, \u003cem\u003eEscherichia coli\u003c/em\u003e, \u003cem\u003eCandida albicans\u003c/em\u003e, \u003cem\u003eC. glabrata\u003c/em\u003e, and \u003cem\u003eC. guilliermondii\u003c/em\u003e [5, 11\u0026ndash;15].\u003c/p\u003e\u003cp\u003eContaminated water poses dual transmission risks: direct patient ingestion and aerosol-mediated dispersion during instrument operation. These aerosols pollute operatory air and environmental surfaces [15\u0026ndash;17], substantially elevating the potential for healthcare-associated infection (HAI). Consequently, DUWLs represent critical reservoirs for nosocomial pathogen transmission, creating significant infection control challenges.\u003c/p\u003e\u003cp\u003eDespite existing research on DUWLs quality determinants [7, 10, 18\u0026ndash;20], methodological limitations persist including single timepoint sampling, restricted culture approaches, incomplete microbial profiling, insufficient outlet coverage, and absence of dynamic daily monitoring. To address these gaps, this study implemented a comprehensive assessment protocol featuring multi-phase sampling across four operational intervals, enhanced pathogen identification via MALDI-TOF MS and Sanger sequencing, biofilm quantification through crystal violet assays, and management practice analysis using structured questionnaires. Our integrated approach aims to characterize contamination dynamics across hospital tiers, identify high-risk biofilm-forming pathogens, and formulate evidence-based infection control protocols for dental settings.\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Study Subjects\u003c/h2\u003e\u003cp\u003eClinical trial number: not applicable. A total of 214 Dental Chair Units (DCU) from 55 healthcare institutions in Nanchang City were selected using stratified random sampling. This included 16 tertiary Grade A hospitals, 9 secondary Grade A or lower hospitals, and 30 private medical institutions. Samples were collected from DUWLs, including source water, handpiece water, triple-syringe water water, and mouth rinse water.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Questionnaire Survey\u003c/h2\u003e\u003cp\u003eA standardized questionnaire was administered by sampling personnel to collect data on: institutional information, DCU configuration, water supply type, DUWLs usage and management practices (including flushing, draining, disinfection protocols, filter replacement frequency, daily patient volume, etc.).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Water Sample Collection\u003c/h2\u003e\u003cp\u003eWater samples were collected according to the following protocol: Source water was obtained at the beginning of the clinical day prior to any water discharge. Samples from the handpiece, triple-syringe water, and mouth rinse outlets were collected at four defined time points: Timepoint 1 (T1) at the beginning of the clinical day without discharging water; Timepoint 2 (T2) at the beginning of the clinical day after discharging 200 mL of water; Timepoint 3 (T3) at the conclusion of the morning clinical session; and Timepoint 4 (T4) at the conclusion of the afternoon clinical session. Before handpiece sampling, air pressure was disabled to prevent aerosolization. Strict aseptic technique was followed: hand hygiene was performed prior to sampling, each outlet was disinfected twice with 75% ethanol swabs and air-dried, and 10 mL of water was collected into sterile tubes. All samples were transported to the laboratory within 1 hour of collection.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Microbiological Testing\u003c/h2\u003e\u003cp\u003eTesting Samples were vortexed thoroughly, and 50 \u0026micro;L aliquots were spread onto Nutrient Agar (NA) plates (90 mm diameter) incubated at 37\u0026deg;C for 48 hours, and Legionella Selective Agar plates incubated at 37\u0026deg;C with 5.0% CO₂ for 120 hours. Total Bacterial Count (TBC) was determined by enumerating colonies using an automated colony counter after incubation, with compliance defined as TBC\u0026thinsp;\u0026le;\u0026thinsp;500 CFU/mL according to the US CDC standard for dental treatment water [150]. Bacterial identification was performed using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS): single colonies were smeared onto a target plate, overlaid with 2 \u0026micro;L of matrix solution A, air-dried, then overlaid with 1.5 \u0026micro;L of matrix solution B, air-dried again, and analyzed by comparing spectra to the reference database. For 16S rRNA gene sequencing, universal primers 27F (5'-AGAGTTTGATCMTGGCTCAG-3') and 1492R (5'-TACGGYTACCTTGTTACGACTT-3') were used for PCR amplification, followed by sequencing and BLASTn analysis against the NCBI database. For strain preservation, single colonies were inoculated into LB broth, incubated overnight at 37\u0026deg;C, mixed with sterile 40% glycerol (800 \u0026micro;L suspension:200 \u0026micro;L glycerol), and stored at -20\u0026deg;C and \u0026minus;\u0026thinsp;80\u0026deg;C.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.5 Biofilm Formation Assay (Crystal Violet Staining)\u003c/h2\u003e\u003cp\u003eBacterial strains were cultured in LB broth to logarithmic growth phase, diluted 1:100 in fresh LB broth to achieve 1.0 \u0026times; 10⁶ CFU/mL, and 200 \u0026micro;L aliquots were added to 96-well microtiter plates with sterile LB broth controls. After static incubation at 37\u0026deg;C for 24 hours, the medium was discarded and wells were gently rinsed thrice with sterile PBS. Biofilms were fixed with 200 \u0026micro;L methanol for 15 minutes, rinsed with PBS, air-dried, stained with 200 \u0026micro;L 0.5% (w/v) crystal violet for 15 minutes, rinsed extensively with physiological saline until colorless, air-dried, and solubilized with 200 \u0026micro;L 33.3% (v/v) glacial acetic acid for 5\u0026ndash;10 minutes.The optical density (OD) of solubilized dye was measured at 570 nm using a microplate reader.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e2.6 Criteria for Biofilm Formation Capacity\u003c/h2\u003e\u003cp\u003eBiofilm formation capacity was classified based on OD₅₇₀ₙₘ relative to blank control wells (ODc): Non-biofilm former (OD\u0026thinsp;\u0026lt;\u0026thinsp;ODc), Weak (ODc\u0026thinsp;\u0026le;\u0026thinsp;OD\u0026thinsp;\u0026lt;\u0026thinsp;2\u0026times;ODc), Moderate (2\u0026times;ODc\u0026thinsp;\u0026le;\u0026thinsp;OD\u0026thinsp;\u0026lt;\u0026thinsp;4\u0026times;ODc), or Strong (OD\u0026thinsp;\u0026ge;\u0026thinsp;4\u0026times;ODc) [151].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e2.7 Statistical Analysis\u003c/h2\u003e\u003cp\u003eData were entered into Excel, cleaned, and analyzed. Descriptive statistics presented normally distributed continuous data as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD), non-normally distributed data as median (interquartile range) [M (Q1, Q3)], and categorical data as frequency (percentage) [n (%)]. Univariate analyses employed Analysis of Variance (ANOVA) for normal continuous data, Kruskal-Wallis H test for non-normal continuous data, and Chi-square (χ\u0026sup2;) test for categorical data. Longitudinal analyses used Repeated Measures ANOVA for normal data or Generalized Estimating Equations (GEE) for non-normal data. Multivariable GEE models (exchangeable correlation matrix) analyzed: 1) TBC (log-transformed if needed) to identify influencing factors, and 2) Handpiece water compliance (binary) status. Statistical significance (α\u0026thinsp;=\u0026thinsp;0.05) was defined as \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 using SPSS 26.0, with figures generated in GraphPad Prism 9.5.0.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Configuration and Management Status of DCUs in Healthcare Institutions\u003c/h2\u003e\u003cp\u003eA total of 214 DCU across 55 institutions were surveyed (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Tertiary Grade A hospital accounted for the highest proportion of DCU (43.46%). Most institutions (67.76%) had\u0026thinsp;\u0026gt;\u0026thinsp;5 DCU. The majority of DCU (70.56%) had been in service for \u0026le;\u0026thinsp;5 years, and 68.69% had a daily patient load of \u0026le;\u0026thinsp;5. Central water treatment systems were the predominant water supply method (57.94%). Compliance with recommended practices was suboptimal: DUWLs disinfection (35.05%), filter replacement according to manufacturer instructions (35.98%), and draining waterlines during non-operational hours (45.79%). Hydrogen peroxide (17.76%) and chlorine-based disinfectants (17.29%) were the most commonly used chemical agents for disinfection.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eConfiguration and Management Status of DCUs Across Multi-Tier Medical Institutions\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCategory\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDCU Count (n\u0026thinsp;=\u0026thinsp;214)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eProportion (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eHealthcare Institution Count (n\u0026thinsp;=\u0026thinsp;55)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eProportion (%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHospital Level\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGrade III, Level A\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e43.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e29.09\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGrade II and below\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e12.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16.36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePrivate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e44.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e54.55\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal Units\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026le;\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e32.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e50.91\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026gt;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e145\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e67.76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e49.09\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYears in Use\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026le;\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e151\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e70.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026gt;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e29.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDaily Patient Volume\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026le;\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e147\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e68.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026gt;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e31.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWater Supply Type\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCentral water treatment\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e124\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e57.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e45.45\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMunicipal tap water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e42.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e54.55\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFilter Replacement\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePer manufacturer's instructions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e35.98\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e20.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNever\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e137\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e64.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e80.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eClinical Specialty\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEndodontics/Conservative Dentistry\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e5.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGeneral Dentistry\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e200\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e93.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOther specialties\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDUWLs Flushing\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBefore/after patient\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e154\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e71.96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e65.45\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNever\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e28.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e34.55\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDUWLs Drainage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDrain during breaks\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e98\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e45.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e63.64\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNever\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e116\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e54.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e36.36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDUWLs Disinfection\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRegularly disinfected\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e35.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e23.64\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNever\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e139\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e64.95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e76.36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDisinfectant Type\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHydrogen peroxide\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e17.76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.45\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChlorine-based disinfectant\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e17.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e18.18\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e139\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e64.95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e76.36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Bacterial Counts and Compliance Rates by Sampling Timepoint and Outlet\u003c/h2\u003e\u003cp\u003eA total of 2,782 water samples were collected (856 handpiece, 856 triple-syringe water, 856 mouth rinse, 214 source water). Bacterial counts differed significantly across timepoints for all outlets (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), demonstrating a significant decrease over time (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Tables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Timepoint 1 (T1, start of day, no flush) exhibited the most severe contamination, with handpiece water showing the highest median bacterial count (1240 CFU/mL) and the lowest compliance rate (10.75%). Compliance rates improved significantly for all outlets after discharging 200 mL of water (T2). Although Timepoint 4 (T4, end of afternoon) had the highest overall compliance, handpiece (83.18%) and triple-syringe water (80.84%) water still exhibited non-compliance rates of 16.82% and 19.16%, respectively. Source water had a median count of 620 CFU/mL and a compliance rate of 46.73%. Compliance rates consistently followed the trend: handpiece water\u0026thinsp;\u0026lt;\u0026thinsp;triple-syringe\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eBacterial colony counts at different water outlets across sampling periods [CFU/mL, M (Q1, Q3)]\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSampling Period\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSample Type\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMedian (M)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIQR (Q1, Q3)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eχ\u0026sup2;\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003ePeriod 1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHandpiece water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1240\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(860,1800)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e285.821\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTriple-syringe water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1080\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(680,1560)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRinse water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e730\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(435,1120)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003ePeriod 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHandpiece water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e610\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(400,1120)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e81.537\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTriple-syringe water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e480\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(320,900)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRinse water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e440\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(240,700)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003ePeriod 3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHandpiece water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e380\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(220,620)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e29.297\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTriple-syringe water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e380\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(220,570)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRinse water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e270\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(180,420)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003ePeriod 4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHandpiece water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(180,460)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e21.519\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTriple-syringe water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e320\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(200,460)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRinse water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e220\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e(100,340)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eBacterial colony counts and pass rates at different water outlets across sampling periods\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"13\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003eHandpiece Water (n\u0026thinsp;=\u0026thinsp;856)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e\u003cp\u003eTriple-syringe Water (n\u0026thinsp;=\u0026thinsp;856)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c9\" namest=\"c7\"\u003e\u003cp\u003eRinse Water (n\u0026thinsp;=\u0026thinsp;856)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003eSource Water (n\u0026thinsp;=\u0026thinsp;214)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTotal Samples\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMedian (CFU/mL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIQR (CFU/mL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCompliance Rate (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMedian (CFU/mL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eIQR (CFU/mL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eCompliance Rate (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eMedian (CFU/mL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eIQR (CFU/mL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eCompliance Rate (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eMedian (CFU/mL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eIQR (CFU/mL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u003cp\u003eCompliance Rate (%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1240\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(860,1800)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e10.75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1080\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(320,900)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e17.76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e730\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e(180,420)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e29.91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e620\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(260,940)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e\u003cp\u003e46.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e856\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e610\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(680,1560)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e41.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e480\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(240,700)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e51.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e440\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e(180,460)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e63.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e642\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e380\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(435,1120)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e68.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e380\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(220,620)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e72.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e270\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e(200,460)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e84.58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e642\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(400,1120)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e83.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e320\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(220,570)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e80.84\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e220\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e(100,340)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e93.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e642\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003ewater\u0026thinsp;\u0026lt;\u0026thinsp;mouth rinse water (except at T4).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Factors Influencing Water Sample Compliance\u003c/h2\u003e\u003cdiv id=\"Sec14\" class=\"Section3\"\u003e\u003ch2\u003e3.3.1 Univariate Analysis\u003c/h2\u003e\u003cp\u003eUnivariate analysis (χ\u0026sup2; test) of factors potentially influencing compliance revealed significant associations. Draining DUWLs during non-operational hours was associated with significantly higher handpiece compliance at T1 (16.33% vs 6.03%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.02) and mouth rinse compliance at T2 (72.45% vs 55.17%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.01) compared to never draining (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Regular DUWLs disinfection significantly improved handpiece compliance at T1 (17.33% vs 7.19%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.02) and mouth rinse compliance at T2 (76.00% vs 56.12%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) compared to no disinfection (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Replacing filters per manufacturer instructions significantly improved mouth rinse compliance at T2 (77.92% vs 54.74%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), handpiece compliance at T4 (90.91% vs 78.83%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.02), and triple-syringe compliance at T3 (81.82% vs 67.88%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.03) and T4 (88.31% vs 76.64%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.037) compared to never replacing filters (Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). DCUs with a daily patient load\u0026thinsp;\u0026le;\u0026thinsp;5 had significantly higher handpiece compliance at T4 compared to those with \u0026gt;\u0026thinsp;5 patients (87.07% vs 74.63%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.02). Hospital level, number of DCU, unit age, water supply method, and flushing practices did not significantly affect compliance rates (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eOne-way ANOVA analysis of pass rates at different water outlets across periods by drainage status [n(%)]\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"16\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c16\" colnum=\"16\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDUWLs Drainage Practice\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eN\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c6\" namest=\"c3\"\u003e\u003cp\u003ePeriod 1 N# (Compliance %)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c9\" namest=\"c7\"\u003e\u003cp\u003ePeriod 2 N# (Compliance %)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003ePeriod 3 N# (Compliance %)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c16\" namest=\"c13\"\u003e\u003cp\u003ePeriod 4 N# (Compliance %)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c15\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c16\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNever drained (n\u0026thinsp;=\u0026thinsp;1392)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e116\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7(6.03)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e18(15.52)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e29(25.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e48(41.38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e59(50.86)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e64(55.17)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e75(64.66)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e82(70.69)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e100(86.21)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e92(79.31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e92(79.31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e105(90.52)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDrained during breaks (n\u0026thinsp;=\u0026thinsp;1176)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e98\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e16(16.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e20(20.41)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e35(35.71)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e41(41.84)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e52(53.06)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e71(72.45)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e71(72.45)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e74(75.51)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e81(82.65)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e86(87.76)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e81(82.65)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e95(96.94)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eχ\u0026sup2;\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2.91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e6.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e0.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e0.51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e2.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e0.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e3.58\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e0.95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e0.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e0.433\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e\u003cp\u003e0.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e0.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e0.54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e0.06\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eOne-way ANOVA analysis of pass rates at different water outlets across periods by disinfection status [n(%)]\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"16\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c16\" colnum=\"16\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDUWLs Disinfection Status\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eN\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003ePeriod 1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e\u003cp\u003ePeriod 2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c12\" namest=\"c9\"\u003e\u003cp\u003ePeriod 3\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c16\" namest=\"c13\"\u003e\u003cp\u003ePeriod 4\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c14\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c15\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c16\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNever disinfected (n\u0026thinsp;=\u0026thinsp;1668)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e139\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10(7.19)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e21(15.11)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e36(25.90)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e54(38.85)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e69(49.64)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e78(56.12)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e90(64.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e98(70.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e\u003cp\u003e120(86.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e112(80.58)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e109(78.42)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e128(92.09)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRegular disinfection (n\u0026thinsp;=\u0026thinsp;900)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13(17.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e17(22.67)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e28(37.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e35(46.67)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e42(56.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e57(76.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e56(74.67)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e58(77.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e\u003cp\u003e61(81.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e66(88.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e64(85.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e72(96.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eχ\u0026sup2;\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e8.27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e2.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e1.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e\u003cp\u003e0.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e1.92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e1.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e1.22\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e\u003cp\u003e0.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e0.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e0.27\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eOne-way ANOVA analysis of pass rates at different water outlets across periods by filter replacement status [n(%)]\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"14\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eFilter Replacement Practice\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eN*\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003ePeriod 1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e\u003cp\u003ePeriod 2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c11\" namest=\"c9\"\u003e\u003cp\u003ePeriod 3\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003ePeriod 4\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u003cp\u003eHandpiece\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\"\u003e\u003cp\u003eSyringe\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c14\"\u003e\u003cp\u003eRinse\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNever replaced (n\u0026thinsp;=\u0026thinsp;1644)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e137\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14(10.22)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e25(18.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e37(27.01)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e54(39.42)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e68(49.64)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e75(54.74)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e91(66.42)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e93(67.88)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e119(86.86)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e108(78.83)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e105(76.64)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e126(91.97)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eReplaced per manufacturer (n\u0026thinsp;=\u0026thinsp;924)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9(11.69)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e13(16.88)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e27(35.06)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e35(45.45)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e43(55.84)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e60(77.92)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e55(71.43)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e63(81.82)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e62(80.52)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e70(90.91)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e68(88.31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e74(96.10)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eχ\u0026sup2;\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e11.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e4.85\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e1.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e5.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e4.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e1.38\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e0.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e0.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e0.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e0.037\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section3\"\u003e\u003ch2\u003e3.3.2 Multivariate GEE Analysis (Handpiece Water)\u003c/h2\u003e\u003cp\u003eMultivariate GEE Analysis handpiece water compliance (\u0026le;\u0026thinsp;500 CFU/mL\u0026thinsp;=\u0026thinsp;compliant, \u0026gt;\u0026thinsp;500 CFU/mL\u0026thinsp;=\u0026thinsp;non-compliant) as the dependent variable (independent variable coding in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). Results (Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e) showed significantly higher odds of non-compliance for handpiece water in secondary Grade A or lower hospitals (OR\u0026thinsp;=\u0026thinsp;2.088, 95%CI: 1.253\u0026ndash;3.481, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005) and private institutions (OR\u0026thinsp;=\u0026thinsp;1.861, 95%CI: 1.178\u0026ndash;2.939, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008) compared to tertiary Grade A hospitals. Regular DUWL disinfection was a significant protective factor, associated with substantially lower odds of non-compliance compared to no disinfection (OR\u0026thinsp;=\u0026thinsp;4.767, 95%CI: 2.321\u0026ndash;9.790, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Unit age, daily patient load, total DCUs, water supply method, flushing practices, draining practices, and filter replacement status showed no statistically significant association with handpiece water compliance (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eVariable assignment instructions\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariable Category\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVariable Name\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCoding Scheme\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBacterial count in water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eY\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u0026thinsp;=\u0026thinsp;Compliant (\u0026le;\u0026thinsp;500 CFU/mL); 1\u0026thinsp;=\u0026thinsp;Non-compliant (\u0026gt;\u0026thinsp;500 CFU/mL)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHospital type\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eX1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026thinsp;=\u0026thinsp;Grade III Level A; 2\u0026thinsp;=\u0026thinsp;Grade II and below; 3\u0026thinsp;=\u0026thinsp;Private\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYears in use\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eX2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026thinsp;=\u0026thinsp;\u0026le;\u0026thinsp;5 years; 2\u0026thinsp;=\u0026thinsp;\u0026gt;\u0026thinsp;5 years\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDaily patient volume\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eX3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026thinsp;=\u0026thinsp;\u0026le;\u0026thinsp;5 patients; 2\u0026thinsp;=\u0026thinsp;\u0026gt;\u0026thinsp;5 patients\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal DCUs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eX4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026thinsp;=\u0026thinsp;\u0026le;\u0026thinsp;5 units; 2\u0026thinsp;=\u0026thinsp;\u0026gt;\u0026thinsp;5 units\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWater supply type\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eX5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026thinsp;=\u0026thinsp;Central water treatment; 2\u0026thinsp;=\u0026thinsp;Municipal tap water\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDUWLs flushing practice\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eX6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026thinsp;=\u0026thinsp;Never; 2\u0026thinsp;=\u0026thinsp;Before/after treatment\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDUWLs drainage practice\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eX7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026thinsp;=\u0026thinsp;Never; 2\u0026thinsp;=\u0026thinsp;Drain during breaks\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDUWLs disinfection practice\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eX8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026thinsp;=\u0026thinsp;Never; 2\u0026thinsp;=\u0026thinsp;Regular disinfection\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFilter replacement practice\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eX9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026thinsp;=\u0026thinsp;Per manufacturer instructions; 2\u0026thinsp;=\u0026thinsp;Never replaced\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab8\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMultivariate GEE analysis of factors affecting pass rates in dental handpiece water\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCategory\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eβ\u003c/em\u003e (SE)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e95% CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eWald \u003cem\u003eχ\u0026sup2;\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eOR (95% CI)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eintercept\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.086 (0.264)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.431 to 0.604\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.107\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.09 (0.65\u0026ndash;1.83)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.743\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eHospital level\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGrade III A (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGrade II and below\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.736 (0.261)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.225 to 1.247\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e7.978\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2.09 (1.25\u0026ndash;3.48)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.005\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePrivate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.621 (0.233)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.164 to 1.078\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e7.088\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.86 (1.18\u0026ndash;2.94)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.008\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eYears in use\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026le;\u0026thinsp;5 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.127 (0.217)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.554 to 0.299\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.343\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.88 (0.58\u0026ndash;1.35)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.558\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDaily patient volume\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026le;\u0026thinsp;5 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.197 (0.191)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.570 to 0.177\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.066\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.82 (0.57\u0026ndash;1.19)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.302\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTotal DCUs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026le;\u0026thinsp;5 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.046 (0.171)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.381 to 0.289\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.072\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.96 (0.68\u0026ndash;1.34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.788\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eWater supply\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCentral treatment (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMunicipal tap water\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.379 (0.194)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.760 to 0.002\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.805\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.69 (0.47-1.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.051\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDUWLs flushing\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNever (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBefore/after treatment\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.294 (0.227)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.739 to 0.152\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.672\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.75 (0.48\u0026ndash;1.16)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.196\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDUWLs drainage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNever (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDrain during breaks\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.214 (0.234)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.673 to 0.245\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.834\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.81 (0.51\u0026ndash;1.28)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.361\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDUWLs disinfection\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNever (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRegular disinfection\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.562 (0.367)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.842 to 2.281\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e18.084\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4.77 (2.32\u0026ndash;9.79)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eFilter replacement\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePer manufacturer (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNever replaced\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.358 (0.262)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.872 to 0.156\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.862\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.70 (0.42\u0026ndash;1.17)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.172\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003e3.4 Microbial Composition and Biofilm Formation Capacity of DUWLs\u003c/h2\u003e\u003cdiv id=\"Sec17\" class=\"Section3\"\u003e\u003ch2\u003e3.4.1 Microbial Species Analysis\u003c/h2\u003e\u003cp\u003eCultivation identified 60 bacterial species comprising 2,123 isolates. Predominant genera included \u003cem\u003eSphingomonas\u003c/em\u003e (12 species, 447 isolates), \u003cem\u003eBacillus\u003c/em\u003e (9 species, 431 isolates), \u003cem\u003eAcidovorax\u003c/em\u003e (7 species, 320 isolates), \u003cem\u003eStaphylococcus\u003c/em\u003e (7 species, 182 isolates), \u003cem\u003eCupriavidus\u003c/em\u003e (3 species, 254 isolates), and \u003cem\u003ePseudomonas\u003c/em\u003e (3 species, 108 isolates). Dominant species varied by outlet (Table\u0026nbsp;\u003cspan refid=\"Tab9\" class=\"InternalRef\"\u003e9\u003c/span\u003e). The top three species overall were \u003cem\u003eBacillus cereus\u003c/em\u003e (6.43%), \u003cem\u003eSphingomonas paucimobilis\u003c/em\u003e (6.39%), and \u003cem\u003eCupriavidus pauculus\u003c/em\u003e (6.19%).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab9\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 9\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComposition of main microorganisms at different water outlets in DUWLs (%)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBacterial Species\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSource Water (n\u0026thinsp;=\u0026thinsp;214)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHandpiece Water (n\u0026thinsp;=\u0026thinsp;856)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTriple-syringe Water (n\u0026thinsp;=\u0026thinsp;856)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRinse Water (n\u0026thinsp;=\u0026thinsp;856)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTotal (n\u0026thinsp;=\u0026thinsp;2782)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBacillus cereus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e7.07\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e6.43\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSphingomonas paucimobilis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e23.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.98\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4.97\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e6.39\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCupriavidus pauculus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e6.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e6.19\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAcidovorax intermedius\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.85\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e6.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4.53\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMicrococcus luteus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.98\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBacillus firmus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4.38\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBacillus paramycoides\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4.06\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBacillus megaterium\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAcidovorax delafieldii\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.82\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCupriavidus metallidurans\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.82\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.51\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNovosphingobium subterraneum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.82\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.43\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSphingobium yanoikuyae\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.12\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section3\"\u003e\u003ch2\u003e3.4.2 Biofilm Formation Capacity\u003c/h2\u003e\u003cp\u003eCrystal violet staining identified 492 isolates (23.2%) with significantly higher biofilm formation than controls (OD₅₇₀ₙₘ \u0026gt;ODc). Among these, 383 (18.0%) were strong biofilm formers (OD₅₇₀ₙₘ \u0026ge; 4\u0026times;ODc) and 5 (0.2%) were moderate formers (2\u0026times;ODc\u0026thinsp;\u0026le;\u0026thinsp;OD₅₇₀ₙₘ \u0026lt; 4\u0026times;ODc). Eight opportunistic pathogens were identified as strong biofilm formers. Their biofilm formation capacity (OD₅₇₀ₙₘ), ranked from strongest to weakest, was: \u003cem\u003eStaphylococcus xylosus\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;\u003cem\u003eBacillus cereus\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;\u003cem\u003eStaphylococcus warneri\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;\u003cem\u003eAcidovorax facilis\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;\u003cem\u003eCupriavidus pauculus\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;\u003cem\u003eAcinetobacter baumannii\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;\u003cem\u003ePseudomonas aeruginosa\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;\u003cem\u003eStaphylococcus hominis\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThis systematic investigation comprehensively assessed contamination status and influencing factors within DUWLs in a representative regional cohort. Findings reveal substantial microbial contamination across surveyed healthcare institutions, posing significant nosocomial infection risks. Analysis of 2,782 water samples collected from 214 DCU across 55 multi-tiered institutions\u0026mdash;at four critical timepoints (pre-operatory 0mL flush, 200mL flush, end of morning/afternoon sessions)\u0026mdash;combined with institutional audits, provides robust evidence on current water quality challenges and their determinants.\u003c/p\u003e\u003cp\u003eWater quality exhibited significant temporal variation. Alarmingly low compliance rates were observed at baseline (T1: no flush) for handpiece (10.75%), triple-syringe (17.76%), and mouth rinse (29.91%) outlets. Compliance substantially improved post-200mL discharge (41.59%, 51.87%, 63.08%; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), aligning with established evidence [21\u0026ndash;23]. While international guidelines recommend flushing DUWLs for 30 seconds to 3 minutes pre-operatively [24\u0026ndash;26], persistent non-compliance at session conclusions (e.g., handpiece: 16.82% at T4) demonstrates that flushing alone is insufficient against mature biofilms [1,27\u0026ndash;31].\u003c/p\u003e\u003cp\u003eOutlet-specific contamination gradients (handpiece\u0026thinsp;\u0026lt;\u0026thinsp;triple-syringe\u0026thinsp;\u0026lt;\u0026thinsp;mouth rinse) predominantly reflect retraction effects: negative pressure upon instrument deactivation aspirates oral microbiota into waterlines [32,6]. Although anti-retraction valves are recommended [33], their high failure rate (74%) [34]\u0026mdash;often linked to inadequate maintenance\u0026mdash;necessitates rigorous valve surveillance protocols [30]. Source water contamination (compliance: 46.73%) further compounds risks by introducing environmental microbes directly into treatment systems [8,35], underscoring the imperative for source water control.\u003c/p\u003e\u003cp\u003eTertiary institutions demonstrated superior compliance, attributable to integrated infection prevention infrastructures (resource allocation, organizational protocols, compliance monitoring) [18,19]. Conversely, primary/secondary and private facilities exhibited critical gaps: low protocol awareness, absent standardized procedures, and poor implementation [36,37]. This disparity mandates tiered regulatory oversight, including mentorship programs pairing tertiary centers with resource-limited institutions and competency-based IPC training.\u003c/p\u003e\u003cp\u003eRegular chemical disinfection emerged as the most effective intervention for DUWLs contamination control (OR\u0026thinsp;=\u0026thinsp;4.767, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), particularly for managing \u003cem\u003eMycobacterium\u003c/em\u003e colonization [38]. However, suboptimal disinfection adherence globally [39,40] reflects persistent knowledge-practice gaps. Complementary measures\u0026mdash;filter replacement per manufacturer guidelines and post-operative waterline drainage\u0026mdash;also improved compliance. Filters provide transient protection but require scheduled maintenance to avoid clogging or becoming secondary reservoirs [33]. Low adoption rates (20%) likely stem from technical complexity, vendor dependence, and cost. While drainage reduces stagnation and biofilm formation, its cumbersome execution (~\u0026thinsp;2\u0026ndash;3 minutes/unit) and lack of automated systems limit uptake (implementation: 63.64%).\u003c/p\u003e\u003cp\u003eMultivariable GEE models identified institutional characteristics influencing water quality: DCU clusters (\u0026gt;\u0026thinsp;5 units) and newer devices (\u0026le;\u0026thinsp;5 years) correlated with improved compliance, likely reflecting enhanced IPC governance [20]. Lower daily patient volumes (\u0026le;\u0026thinsp;5) also improved outcomes, potentially due to reduced retraction frequency and cumulative biofilm burden [42]. Water supply systems (central vs. independent), flushing protocols, and device age showed no significant association\u0026mdash;possibly confounded by municipal water quality, inconsistent filter maintenance, and biofilm resilience post-maturation [12].\u003c/p\u003e\u003cp\u003eOur analysis of DUWLs reveals a complex ecosystem harboring clinically significant pathogens with critical implications for infection control in dental practice. The microbial profile demonstrates concerning prevalence of opportunistic pathogens and biofilm-forming species, creating dual challenges for waterline maintenance and patient safety.\u003c/p\u003e\u003cp\u003e\u003cb\u003eClinically Significant Pathogens in DUWLs\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003eSphingomonas\u003c/em\u003e species emerged as dominant aquatic bacteria in our samples, consistent with reports showing 38% prevalence in purified laboratory water systems [43] and contamination of endoscope rinse water [44]. Particularly problematic is \u003cem\u003eS. paucimobilis\u003c/em\u003e (6.39% prevalence), which survives disinfectants and nutrient-poor conditions while demonstrating pan-drug resistance to β-lactams, aztreonam, and polymyxin B [45]. This pathogen accounts for 86.7% of healthcare-associated \u003cem\u003eSphingomonas\u003c/em\u003e infections [46], including hemodialysis-related bloodstream outbreaks [47] and post-cataract endophthalmitis [48], confirming DUWLs as reservoirs for multidrug-resistant organisms.\u003c/p\u003e\u003cp\u003e\u003cem\u003eBacillus cereus\u003c/em\u003e (6.43% prevalence) challenges traditional perceptions as merely an environmental contaminant. Our findings align with evidence of its pathogenic potential, causing sepsis and CNS infections [49] across diverse populations (neonates 41%, elderly 26%, adults 23%) with 21% mortality in systemic infections [50].\u003c/p\u003e\u003cp\u003eNotable \u003cem\u003estaphylococcal\u003c/em\u003e species include:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eS. xylosus\u003c/em\u003e (2.44%): Associated with persistent endodontic infections [51]\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eS.hominis\u003c/em\u003e: Exhibiting alarming resistance (100% penicillin, 82.9% oxacillin) in hematology patients [52]\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eHigh-priority nosocomial pathogens were also identified in Table\u0026nbsp;\u003cspan refid=\"Tab10\" class=\"InternalRef\"\u003e10\u003c/span\u003e.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab10\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 10\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePathogen\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePrevalence\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eClinical Concern\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eA. baumannii\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.83%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eResistance surge (23%\u0026rarr;63%, 2004\u0026ndash;2014) [53]; causes complex infections [54]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eP. aeruginosa\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDetected\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e51,000 annual U.S. HAIs; limited therapeutic options [55]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eC. pauculus\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.19%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eFatal respiratory infections in immunocompromised [56]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eWhile \u003cem\u003eLegionella\u003c/em\u003e was culture-negative in our study \u0026ndash; likely due to viable-but-non-culturable (VBNC) states \u0026ndash; its detection in other DUWLs studies (0-100%) [57, 58] warrants ongoing vigilance.\u003c/p\u003e\u003cp\u003e\u003cb\u003eBiofilm Formation Dynamics and Challenges\u003c/b\u003e\u003c/p\u003e\u003cp\u003eDUWLs provide ideal biofilm conditions through: 1) persistent moisture/stagnation, 2) nutrient enrichment from oral fluid retraction, 3) bacterial adhesion on polyurethane surfaces, and 4) aggregation in narrow lumens. This facilitates rapid colonization within 8 hours of operation [59].\u003c/p\u003e\u003cp\u003eBiofilms represent complex microbial communities encased in extracellular polymeric substance (EPS) matrices [60]. While prior studies characterized DUWLs biofilm diversity (824 taxa [71]), viability [61], and antibiotic resistance [62], key biofilm-forming species remained unidentified.\u003c/p\u003e\u003cp\u003eUsing crystal violet semi-quantitative staining, we found 23.2% (492/2,123) of isolates formed biofilms, with 18% (383) exhibiting strong capacity. Eight species demonstrated exceptional biofilm proficiency:\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eB\u003c/em\u003e. \u003cem\u003ecereus\u003c/em\u003e (disinfectant-resistant biofilms [63])\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eA. baumannii\u003c/em\u003e (\u0026gt;\u0026thinsp;90% clinical isolates form biofilms [64])\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eP. aeruginosa\u003c/em\u003e (rapid 8-12h adhesion [65])\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eC. pauculus\u003c/em\u003e (outperforms \u003cem\u003eP. aeruginosa\u003c/em\u003e in certain conditions [66])\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eA. intermedius\u003c/em\u003e (enhances \u003cem\u003eL. pneumophila\u003c/em\u003e colonization [67])\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eS. Warneri\u003c/em\u003e\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eS. Hominis\u003c/em\u003e\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eS. Xylosus\u003c/em\u003e\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003cp\u003eOf particular concern, A. intermedius promotes colonization of \u003cem\u003eL. pneumophila\u003c/em\u003e \u0026ndash; associated with 33% pneumonia mortality [68]. \u003cem\u003eStaphylococcal\u003c/em\u003e findings align with literature: \u003cem\u003eS. xylosus\u003c/em\u003e is the most proficient biofilm-former among coagulase-negative \u003cem\u003estaphylococci\u003c/em\u003e [69], while\u0026thinsp;\u0026gt;\u0026thinsp;50% of \u003cem\u003eS. hominis\u003c/em\u003e bloodstream isolates form robust biofilms [70].\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eThis study confirms the severity of microbial contamination in DUWLs within clinical settings, identifying critical influencing factors and characterizing the microbiological profile. Significantly, we provide the first systematic identification of key opportunistic pathogens with strong biofilm-forming capacity in DUWLs, including \u003cem\u003eStaphylococcus xylosus\u003c/em\u003e, \u003cem\u003eBacillus cereus\u003c/em\u003e, and \u003cem\u003eStaphylococcus warneri\u003c/em\u003e. These findings establish a vital theoretical foundation for advanced mechanistic understanding of DUWLs contamination dynamics, development of targeted and safe disinfection strategies against core biofilm-forming species, and evidence-based optimization of waterline management protocols.\u003c/p\u003e\u003cp\u003eCollectively, these insights deliver actionable guidance for mitigating DUWLs contamination and preventing dental care-associated nosocomial infections, emphasizing the imperative for enhanced disinfection protocols\u0026mdash;particularly in resource-limited settings.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNa Li initiated the research concept and contributed to study design. Fuqing Chen, Qiaoqiao Hu and Fen Yang performed data acquisition and partial experimental procedures. Yuxin Qin, Jing Guo and Nuodan Wu carried out data analysis and statistical interpretation. Yuting Li participated in manuscript preparation. All authors critically reviewed and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the National Natural Science Fund of China [grant number: 82460192].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe 16S rRNA gene sequences generated during this study have been deposited in the NCBI GenBank database under the accession number range PX365876 to PX365917. These records are currently undergoing the final release processing by NCBI and will become fully accessible at the following URL shortly: https://www.ncbi.nlm.nih.gov/nuccore/PX365876. The accession numbers are guaranteed and can be verified as assigned by contacting [email protected] with the submission ID SUB15638281.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted in accordance with the Declaration of Helsinki and approved by the ethics committee of The First Affiliated Hospital of Nanchang University, Nanchang, China. Written informed consent was obtained from all participants.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eO\u0026apos;Donnell MJ, Shore AC, Russell RJ, et al. Optimisation of the long-term efficacy of dental chair waterline disinfection by the identification and rectification of factors associated with waterline disinfection failure. J Dent. 2007;35(5):438-51. https://doi.org/10.1016/j.jdent.2007.01.001\u003c/li\u003e\n\u003cli\u003eHahn MW. The microbial diversity of inland waters. Curr Opin Biotechnol. 2006;17(3):256-61. https://doi.org/10.1016/j.copbio.2006.05.006\u003c/li\u003e\n\u003cli\u003eMills SE. 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Prevalence of ESBL and MBL encoding genes in \u003cem\u003eAcinetobacter baumannii\u003c/em\u003e strains isolated from patients of intensive care units (ICU). Saudi J Biol Sci. 2015;22(4):424-9.\u003c/li\u003e\n\u003cli\u003eFujii A, Seki M, Higashiguchi M, et al. Community-acquired, hospital-acquired, and healthcare-associated pneumonia caused by \u003cem\u003ePseudomonas aeruginosa\u003c/em\u003e. Respir Med Case Rep. 2014;12:30-3.\u003c/li\u003e\n\u003cli\u003eFiel DCRC E. \u003cem\u003eCupriavidus pauculus\u003c/em\u003e causing a respiratory tract infection in a post-kidney-transplant patient: A firstly described rare clinical case. Pharm Pharmacol Int J. 2020;8(1):34-6.\u003c/li\u003e\n\u003cli\u003eTang CC, Sun W, Tan Z, et al. Investigation on the distribution of microbial communities in dental unit waterlines of medical institutions. Chin J Disinfect. 2021;38(11):856-9. (in Chinese)\u003c/li\u003e\n\u003cli\u003eZhou RY, Ping YF, Zhang Y, et al. 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Hospital sink traps as a potential source of the emerging multidrug-resistant pathogen \u003cem\u003eCupriavidus pauculus\u003c/em\u003e: characterization and draft genome sequence of strain MF1. J Med Microbiol. 2022;71(2):001501.\u003c/li\u003e\n\u003cli\u003eChatfield CH, Zaia J, Sauer C. \u003cem\u003eLegionella pneumophila\u003c/em\u003e Attachment to Biofilms of an \u003cem\u003eAcidovorax\u003c/em\u003e Isolate from a Drinking Water-Consortium Requires the Lcl-Adhesin Protein. Int Microbiol. 2020;23(4):597-605.\u003c/li\u003e\n\u003cli\u003eChahin A, Opal SM. Severe Pneumonia Caused by \u003cem\u003eLegionella pneumophila\u003c/em\u003e: Differential Diagnosis and Therapeutic Considerations. Infect Dis Clin North Am. 2017;31(1):111-21.\u003c/li\u003e\n\u003cli\u003eTremblay YD, Lamarche D, Chever P, et al. Characterization of the ability of coagulase-negative staphylococci isolated from the milk of Canadian farms to form biofilms. J Dairy Sci. 2013;96(1):234-46.\u003c/li\u003e\n\u003cli\u003eSzczuka E, Telega K, Kaznowski A. Biofilm formation by \u003cem\u003eStaphylococcus hominis\u003c/em\u003e strains isolated from human clinical specimens. Folia Microbiol (Praha). 2015;60(1):1-5.\u003c/li\u003e\n\u003cli\u003eFan C, Gu H, Liu L, et al. Distinct Microbial Community of Accumulated Biofilm in Dental Unit Waterlines of Different Specialties. Front Cell Infect Microbiol. 2021;11:670211. https://doi.org/10.3389/fcimb.2021.670211\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Dental unit waterlines, Opportunistic pathogens, Biofilm, Microbial contamination, Nosocomial infection, Disinfection","lastPublishedDoi":"10.21203/rs.3.rs-7419035/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7419035/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDental unit waterlines (DUWLs) are susceptible to microbial contamination, posing significant infection risks. This study aimed to assess microbial contamination levels, identify biofilm-forming pathogens, and evaluate infection control practices in DUWLs across multi-tier medical institutions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA cross-sectional study was conducted using stratified random sampling of 214 dental chair units (DCU) from 55 medical institutions (16 tertiary, 9 secondary/below-level, and 30 private) in Nanchang, China. DUWLs management data were collected via questionnaires. Water samples were collected from four sites (source water, handpiece, triple-syringe, and rinse water; total n = 2,782) at four time points: pre-operation (0 mL drainage), after 200 mL drainage, and at the end of morning and afternoon sessions. Bacterial counts were cultured on nutrient and Legionella agars, with compliance defined as ≤ 500 CFU/mL. Species identification was performed using MALDI-TOF MS and Sanger sequencing. Biofilm formation was quantified by crystal violet staining (OD₅₇₀ₙₘ). Risk factors were analyzed using generalized estimating equations (GEE).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSevere DUWLs contamination was observed. Pre-operation compliance rates were 10.75% (handpieces), 17.76% (triple-syringes), and 29.91% (rinse water). Drainage of 200 mL significantly improved compliance (41.59–63.08%). Despite the highest compliance rates observed at the end of sessions (time point 4), 16.82% of handpiece and 19.16% of triple-syringe samples still exceeded the limit. Source water compliance was 46.73%. Tertiary hospitals demonstrated better water quality compared to secondary/private institutions. Multivariate GEE analysis indicated a higher contamination risk in handpieces from secondary/below-level (OR = 2.088, 95% CI: 1.253–3.481, \u003cem\u003eP\u003c/em\u003e = 0.005) and private institutions (OR = 1.861, 95% CI: 1.178–2.939, \u003cem\u003eP\u003c/em\u003e = 0.008) compared to tertiary hospitals. Regular disinfection was identified as a protective factor (OR = 4.767, 95% CI: 2.321–9.790, \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001).Among 2,123 isolates (60 species), dominant genera included \u003cem\u003eSphingomonas\u003c/em\u003e (447 strains), \u003cem\u003eBacillus\u003c/em\u003e (431), and \u003cem\u003eAcidovorax\u003c/em\u003e (320). A total of 383 (18.0%) isolates were identified as strong biofilm formers. Eight opportunistic pathogens were ranked by biofilm-forming capacity (OD₅₇₀ₙₘ) as follows:\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eStaphylococcus xylosus\u003c/em\u003e \u0026gt; \u003cem\u003eBacillus cereus\u003c/em\u003e \u0026gt; \u003cem\u003eStaphylococcus warneri\u003c/em\u003e \u0026gt; \u003cem\u003eAcidovorax mediterraneus\u003c/em\u003e \u0026gt; \u003cem\u003ePseudomonas otitidis\u003c/em\u003e \u0026gt; \u003cem\u003eAcinetobacter baumannii\u003c/em\u003e \u0026gt; \u003cem\u003ePseudomonas aeruginosa\u003c/em\u003e \u0026gt; \u003cem\u003eStaphylococcus hominis\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDUWLs contamination is severe, with biofilm colonization being a core concern. Hospital tier (tertiary vs. non-tertiary) and regular disinfection significantly affect water quality. This study is the first to systematically identify eight strong biofilm-forming opportunistic pathogens in DUWLs, providing a scientific basis for targeted disinfection and optimized waterline management. Urgent interventions—emphasizing effective disinfection and enhanced infection control in primary care—are warranted.\u003c/p\u003e","manuscriptTitle":"Microbial contamination and biofilm-forming pathogens in dental unit waterlines: A cross- sectional study of opportunistic bacteria and infection control implications in an urban setting of China","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-22 03:03:22","doi":"10.21203/rs.3.rs-7419035/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-13T15:56:22+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-22T10:52:55+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-16T19:42:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"232453025978030642114878493550214813315","date":"2025-10-13T06:10:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"283105323152539786826237593711977400422","date":"2025-10-08T18:35:59+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-08T18:24:47+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-08T18:19:04+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-09-30T07:42:10+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-29T05:12:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2025-09-28T12:21:01+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3510b970-fab0-4784-abc1-ceaa1344c939","owner":[],"postedDate":"October 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-13T11:24:04+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-22 03:03:22","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7419035","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7419035","identity":"rs-7419035","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}