{"paper_id":"2fbf2783-8ccd-4ceb-be89-7595da91f84e","body_text":"Evaluation of Proximal Contact Integrity and Associated Factors in Posterior Resin Composite Restorations: A Cross-sectional Study in Nairobi, Kenya | 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 Evaluation of Proximal Contact Integrity and Associated Factors in Posterior Resin Composite Restorations: A Cross-sectional Study in Nairobi, Kenya Umaru Kizito, Lois Keren Kisakye, Hazel Orengo Simila, Fred Odera Otieno, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8547564/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 19 You are reading this latest preprint version Abstract Background The global shift from dental amalgam to direct posterior resin composite restorations (RCRs), driven by aesthetic demands and the Minamata Convention, has increased the need to evaluate their clinical performance. Establishing proper proximal contact tightness (PCT) in Class II restorations is a critical, technique-sensitive parameter required to prevent food impaction, periodontal disease, and restoration failure. In Nairobi, Kenya, there is a lack of local data regarding technical failures like deficiencies in proximal contact integrity. This study aimed to evaluate the proximal contact tightness of Class II posterior RCRs placed over a five-year period in selected dental institutions in Nairobi. Methods A cross-sectional study was conducted at three sites: a private facility (UoNDP), a teaching hospital (UoNDS), and a public hospital (KNHDD). A total of 159 Class II RCRs placed between 2014 and 2019 were selected for clinical examination. PCT was assessed using a tactile method with dental floss and categorized as tight, too tight, loose, or open, utilizing a modified United States Public Health Survey (USPHS) tool. Data were analyzed using STATA version 19, employing Chi-square tests and multivariate analysis to identify associated factors. Results Of the 139 assessable restorations (20 were excluded due to missing adjacent teeth), 56.8% (n = 79) had tight contacts, while 43.2% (n = 60) exhibited unacceptable proximal tightness (22.3% loose and 20.9% open). Disparities between facilities were significant; 75% of restorations at KNHDD had unacceptable contacts, compared to 26.7% at UoNDP and 30% at UoNDS. Multivariate analysis revealed that placement at KNHDD was strongly associated with both open (aRRR = 4.71, p = 0.008) and loose contacts (aRRR = 33.88, p < 0.001). Additionally, secondary caries showed a significant association with loose contacts (aRRR = 6.08, p = 0.02). Conclusions The study found a high prevalence (43.2%) of inadequate proximal contacts in Class II posterior RCRs in Nairobi, Kenya. This underscores a critical quality gap in restorative procedures, particularly in public hospital settings. There is an urgent need for enhanced educational initiatives and professional development to improve clinical techniques and ensure the long-term success of composite restorations in the region. Resin composite restorations Proximal contact tightness Class II restorations Nairobi Kenya USPHS Figures Figure 1 Figure 2 Figure 3 Figure 4 BACKGROUND Dental resin composite, a tooth-coloured restorative material, has been used for more than half a century in the treatment of dental caries affecting both anterior and posterior teeth [ 1 ]. In the past, dental amalgam was the preferred material for posterior restorations [ 2 ]. However, growing patient demand for aesthetic solutions, the favourable properties of composite restorations, and the global Minamata convention on mercury advocating for an amalgam phase-down by individual countries have led to an increased preference for direct posterior resin composite restorations (RCRs) [ 3 ]. This transition underscores the need for careful assessment of RCR performance, particularly in high stress-bearing posterior areas. The placement of RCRs is highly technique sensitive as it requires the balance of multiple conditions for achieving long-lasting restorations [ 4 ]. Moisture control is essential because moisture can compromise bonding, so methods like rubber dam isolation are recommended [ 5 ]. The cavity should be modified to expose more enamel for stronger bonding, and the composite should be placed incrementally to reduce polymerization shrinkage [ 5 ]. Proper conditioning of enamel and dentine helps ensure good adhesion. Effective light curing is also critical, as the intensity and exposure time of the curing unit affect the composite’s degree of conversion and hardness. Aesthetic goals such as colour match, stable shade, smooth finish, long-term gloss and good polishability also need attention [ 5 ]. Long-term success depends on accurate anatomical contouring and well-sealed margins to prevent leakage and discoloration [ 6 ]. For Class II cavities, which involve the mesial-occlusal (MO), distal-occlusal (DO), and mesial-occlusal-distal (MOD) proximal surfaces, reconstruction of proximal contacts in a specialized manner is crucial to prevent fractures and preserve tooth structure [ 7 – 9 ]. Literature shows that achieving tight proximal contacts with Class II composites remains a challenge: in one systematic review of contact outcomes, only about 6% of restorations had tight contacts while open contacts occurred in 61.6% of cases [ 10 ]. PCT is one of the specialized parameters assessed for Class II restorations [ 11 ]. Matrix systems play a critical role in establishing proper proximal morphology. When correctly positioned, the matrix complex enables accurate reconstruction of the proximal wall and reduces the risk of overhangs or open contacts [ 12 – 14 ]. Failure to establish an adequate proximal contact is a commonly reported complication and a significant factor in RCR failure. It can lead to localized periodontitis and gingivitis due to food impaction [ 11 ]. In clinical settings, PCT is conventionally assessed using the tactile method with dental floss. The contact is ideal if the floss passes through with a \"snap\" [ 15 ]. Assessment includes recording whether contacts are too tight (difficult to place/withdraw), tight (reasonable placement/withdrawal), loose, or open (no resistance) [ 15 ]. Despite the growing indication for RCRs globally, there is a noted burden on healthcare systems due to the failure of posterior RCRs, often leading to replacement or complex treatments [ 16 ]. In Nairobi, Kenya, where RCR use is increasing [ 17 ], local data regarding the longevity, failure rates, and specific technical failures, such as deficiencies in proximal contact integrity, are lacking. This research therefore aimed to address this gap by assessing the integrity of proximal contacts in Class II posterior RCRs placed in selected institutions in Nairobi, Kenya, thereby contributing to the comprehensive understanding of RCR performance in this region. The core objective of the parent study was to evaluate the performance of direct posterior resin composite restorations placed over a 5-year period in Nairobi, Kenya. METHODS Study aim and design The aim of this study was to evaluate proximal contact tightness and associated factors of Class II posterior resin composite restorations placed over a 5-year period at University of Nairobi Dental School, University of Nairobi Dental Plaza, and Kenyatta National Hospital Dental Department in Nairobi, Kenya. This study utilized a cross-sectional study design. Study setting This research study was conducted in Nairobi County, Kenya across 3 distinct dental clinic al settings conveniently sampled for their institutional diversity: the University of Nairobi Dental School (UoNDS) , a teaching hospital; the University of Nairobi Dental Plaza (UoNDP) , a private facility; and the Kenyatta National Hospital Dental Department (KNHDD) , a public hospital. Study Population The study population consisted of patients with posterior RCRs placed at the three selected sites between 2014 and 2019. Sample Size Determination and Sampling The target sample size was initially calculated using Kish Leslie’s method for a single proportion, assuming a 50% prevalence of posterior RCRs. The final calculated sample size, adjusted for a population estimate of 1000, was 278 RCRs. This total was divided equally, aiming for 93 restorations per study area and 19 per year of study per site. Ultimately, a total of 286 posterior RCRs distributed among 95 participants were examined. While the parent study initially examined 286 restorations from 95 participants including class I, II, and V restorations, a specialized subset of 159 Class II RCRs was selected for this investigation into proximal contact integrity. The study sites were selected using convenient sampling. Participants were identified through patient records and daily work registers. A stratified random sampling approach was employed to select participants, based on the year of placement of the RCR and the specific facility. Selection Criteria Inclusion Criteria : Participants who consented to the study. Participants who had class II direct posterior composite restorations on permanent posterior teeth placed between 2014 and 2019 with proper records. Participants above 18 years of age. Exclusion Criteria : Participants with incomplete records about the RCRs. Participants who did not consent. Indirect RCRs as per dental records. 4. Posterior RCRs on deciduous teeth or permanent teeth apart from premolars and molars. Data Collection Instruments and Techniques After obtaining approval to access patient records, a list of individuals who received posterior composite restorations from 2014 to 2019 was compiled. Ninety-five eligible participants were recruited, contributing a total of 286 restorations evenly distributed across the study sites. Participants were contacted by phone using numbers from their dental records and scheduled for appointments based on their availability and that of the lead investigator. Each participant received a one-hour appointment. Written informed consent in English or Swahili was obtained after the study was fully explained and any questions addressed. All personal and clinical information was handled confidentially, and participation was entirely voluntary. Clinical Examination Clinical examination was performed in a clinical setting utilizing a dental mirror, dental explorer, and a WHO periodontal probe. Clinical Data Collection Tool (USPHS) The clinical performance of the posterior RCRs was evaluated using a modified version of the United States Public Health Survey (USPHS) tool for tooth-coloured restorations. Proximal Contact Tightness Assessment To measure proximal tightness for Class II composite restorations, waxed single strand dental floss, approximately 20 cm in length, was utilized. Observations were recorded to establish whether the contacts were: Tight: Reasonable placement and withdrawal of floss Loose: Minimal resistance to floss Open: No resistance on placement and withdrawal of floss. Data Validity and Reliability Intra-examiner reliability was assessed using Cohen’s Kappa, yielding a value of 0.90, which demonstrated perfect reliability and validity. Data Analysis Data was cleaned and analysed using STATA version 19. Categorical variables were summarized with proportions and percentages. Chi-square tests were used to explore associations between PCT and factors such as secondary caries, tooth type, dental facility and restoration surface. Multinomial regression was used to determine factors associated with PCT. Factors to be included in the multivariate analysis were selected at bivariate analysis at a p - value < 0.2. Interaction terms were formed between significant variables, and a likelihood ratio test was used to check for the presence of interaction. There was no significant interaction. Stepwise estimation was done to maintain only significant variables. Thereafter, the data was checked for confounding with a percentage change greater than 10% used to confirm the presence of a confounder. Ethical Considerations and Consent Written informed consent was sought from participants in either Swahili or English after thorough explanation of the study, its risks, and benefits. Ethical approval was obtained from The Kenyatta National Hospital-University of Nairobi Ethics and Research Committee (Protocol No. P760/08/2019). RESULTS The study examined a total of 159 Class II RCRs. The USPHS clinical evaluation tool was used, with modifications made for Class II composite restorations to measure proximal tightness. This assessment focused on restorations placed on mesial-occlusal/distal-occlusal (MO/DO) and mesial-occlusal-distal (MOD) surfaces. Distribution of Class II Restorations according to tooth surface The MO/DO surfaces dominated the restoration surfaces examined at 145 (91.2%) of all RCRs, while MOD restorations accounted for 14 (8.8%). This is represented in Fig. 1 below. Proximal Contact Tightness Findings Proximal contact tightness analysis was conducted on 139 of the 159 class II RCRs (MO/DO and MOD), given that 20 of the class II restorations could not be assessed due to the absence of adjacent teeth. A sizable majority of these restorations, 79 (56.8%), were found to have tight contacts. However, a total of 60 (43.2%) were found to have unacceptable proximal tightness, defined as having loose or open contacts. Of these 60, 31(51.7%) were loose whereas 29 (48.3%) were open. The findings from proximal contact tightness analysis are represented in Fig. 2 below. Distribution of PCT among facilities Of all 139 class II RCRs assessed for proximal contact tightness, 45 (32.4%) were done at UoNDP while 50 (35.9%) and 44 (31.7%) were done at UoNDS and KNHDD respectively. A significantly higher proportion (75%) of restorations at KNHDD exhibited unacceptable (loose and open) contacts. In comparison, unacceptable contacts were observed in 26.7% of class II restorations at UoNDP and 30% at UoNDS. This distribution is represented in Fig. 3 below. Distribution of PCT among tooth type Among the 139 class II RCRs assessed for proximal contact tightness, 67 were molars and 72 were premolars. A slightly higher proportion of molars 44.8% of had unacceptable contacts, defined as loose or open while 41.7% of premolars had unacceptable contacts. These findings are shown in Fig. 4 below. Association of PCT with other factors Chi-square tests showed significant association between proximal contact tightness and secondary caries (χ² = 8.05, p = 0.018), as well as the facility at which the restoration was placed (χ²= 30.77, p < 0.001). The results of the chi-square tests are shown in Table 1 below. Table 1 Chi-square tests of association between PCT and other factors Factor Chi-square value (χ²) p-value Restoration surface 0.27 0.875 Secondary caries 8.05 0.018 Facility 30.77 < 0.001 Tooth type 0.74 0.691 Multivariate analysis included the surface of the restoration, tooth type, secondary caries and the facility at which the restoration was placed. The presence of secondary caries showed a significant association with proximal contact tightness when loose contacts were compared to tight contacts (RRR = 6.08, p = 0.02, 95% CI 1.94–19.06) but showed no significant association among open contacts. Among the facilities, KNH showed a significant association with proximal contact tightness when both open contacts (RRR = 4.71, p = 0.008, 95% CI 1.50–14.80) and loose contacts (RRR = 33.88, p < 0.001, 95% CI 6.15–186.61) were compared to tight contacts. The results for multivariate analysis are shown in Table 2 below. Table 2 Multivariate analysis of factors associated with PCT Factor PCT aRRR 95%CI P-value Secondary caries Present Open vs Tight 1.84 0.55–6.20 0.326 Present Loose vs Tight 6.08 1.94–19.06 0.002 Facility KNHDD Open vs Tight 4.71 1.50–14.80 0.008 KNHDD Loose vs Tight 33.88 6.15–186.61 < 0.001 UoNDS Open vs Tight 0.45 0.12–1.66 0.232 UoNDS Loose vs Tight 3.99 0.76–20.89 0.101 aRRR = adjusted relative risk ratio DISCUSSION The findings from this study provide novel insights into PCT among class II RCRs in a Kenyan dental setting, revealing a high prevalence of unacceptable contacts (43.2%) among 139 assessable restorations. Tight contacts predominated at 56.8%, yet the substantial proportion of loose (22.3%) and open (20.9%) contacts underscores a critical quality gap in the placement of posterior RCRs. This observation mirrors concerns reported in the previous literature about the difficulty of consistently forming optimal contacts with composite materials. El-Badrawy et al found that a high proportion of Class II composite restorations had open or inadequate proximal contacts depending on placement technique, in contrast to amalgam restorations that more frequently produced acceptable contacts[ 18 ]. Predominantly MO/DO surfaces (91.2%) were evaluated, reflecting common clinical practice reports from literature [ 19 , 20 ], while the inability to assess 20 restorations (12.6%) due to missing adjacent teeth highlights a real-world challenge in PCT evaluation. Tooth type yielded comparable unacceptable rates (44.8% for molars and 41.7% for premolars), even with a chi-square test showing no significant difference between the two (χ²=0.74, p = 0.691), therefore suggesting that technique rather than anatomy drove outcomes here. Facility-level disparities were striking, with KNHDD showing 75% unacceptable contacts compared to 26.7% at UoNDP and 30% at UoNDS. Multivariate analysis confirmed KNHDD’s strong association with both open (aRRR = 4.71, 95% CI: 1.50–14.80, p = 0.008) and loose contacts (aRRR = 33.88, 95% CI: 6.15–186.61, p < 0.001) compared to tight contacts. This trend may indicate an operator-related factor, where clinicians in Kenya might deliberately or inadvertently create open margins, possibly under the belief that it enhances oral hygiene access [ 21 ] or due to limitations in matrix systems used[ 22 , 23 ], particularly in public dental clinics or teaching environments. Secondary caries showed a significant bivariate association with PCT (χ²=8.05, p = 0.018) and persisted for loose contacts compared to tight contacts at multivariate analysis. (RRR = 6.08, 95%CI: 1.94–19.06, p = 0.02). These findings align with those reported by Sharafat et al who demonstrated a strong association between defective proximal contacts and caries development in adjacent teeth [ 24 ]. Notably, no such link was shown for open contacts. This difference may reflect variations in plaque retention, food impaction, and challenges in interproximal cleaning associated with loose contacts, or even a limited sample size. Loose contacts facilitate microbial ingress accelerating demineralization at restoration margins, a well-documented pathway in studies [ 25 ]. Inadequate contacts also allow food impaction in the interdental spaces, the consequences of which include localized gingival inflammation and periodontitis, which can exacerbate tissue destruction and ultimately precipitate restoration failure [ 26 ]. Patients may require more frequent recalls, repairs, or even premature replacement of restorations, imposing additional costs and patient discomfort. Proximal contact tightness is paramount for the longevity and success of restorations as it directly influences the functional and aesthetic outcomes, as well as the long-term viability of the restoration [ 11 ]. Indeed, a longitudinal study with up to 10 years of follow-up identified loss of proximal contact as a leading cause of failure for posterior composite restorations [ 27 ]. The observed deficiencies in proximal contact integrity in this study setting suggest that there may be a lack of understanding or application of the principles of adhesion and contact mechanics during the restorative process. This calls for enhanced educational initiatives aimed at equipping practitioners with the skills necessary to optimize the placement of RCRs, thereby reducing the risk of failure. Furthermore, ongoing professional development programs could be instrumental in disseminating the latest research findings and techniques in restorative dentistry. These findings provide a useful baseline for future research on the performance of resin composite restorations in Kenya. The lack of local evidence on longevity and failure rates has limited understanding of their clinical behaviour, and this study helps fill that gap. Further research could investigate specific operator techniques associated with contact failures, explore motivational or educational factors influencing clinical decisions around contact tightness, and evaluate interventions like matrix system enhancements or restorative material innovations that improve proximal contact integrity. Additionally, longitudinal follow-up studies examining the association between proximal contact integrity and other clinical outcomes, including caries recurrence, periodontal health, and patient satisfaction, would provide valuable comprehensive insights to guide clinical practice and policy planning in Kenya and similar settings. Strengths and Limitations The research directly addresses the noted lack of local data regarding deficiencies in PCT, one of the specialized parameters and a key determinant of restoration success for Class II restorations using RCRs, in Nairobi, Kenya. The cross-sectional design of the study however presented a limitation in that it precluded the establishment of a cause-and-effect relationship regarding PCT and restoration failure. CONCLUSIONS The study demonstrates that the prevalence of inadequate proximal contacts (43.2%) is considerably high among Class II posterior resin composite restorations (RCRs) in Nairobi, Kenya. This underscores a critical quality gap in the clinical performance of these restorations, particularly within public hospital settings where unacceptable contacts were significantly more frequent. Because inadequate proximal integrity is strongly associated with secondary caries and can lead to localized periodontal issues and premature restoration failure, establishing proper contact tightness is paramount for long-term clinical success. These findings suggest a need for enhanced educational initiatives and professional development to equip dental practitioners in Kenya with better skills in adhesion and contact mechanics. Furthermore, this research provides a vital baseline for future longitudinal studies to evaluate the impact of proximal contact integrity on caries recurrence and patient satisfaction in the region. Abbreviations aRRR Adjusted relative risk ratio CI Confidence interval DO Distal-occlusal KNHDD Kenyatta National Hospital Dental Department MO Mesial-occlusal MOD Mesial-occlusal-distal PCT Proximal contact tightness RCRs Resin composite restorations UoNDS University of Nairobi Dental School UoNDP University of Nairobi Dental Plaza USPHS United States Public Health Survey WHO World Health Organization Declarations Ethics approval and consent to participate The study received ethical clearance and approval from the Kenyatta National Hospital-University of Nairobi Ethics and Research Committee (Protocol No. P760/08/2019). Participation was entirely voluntary, and written informed consent was obtained from all participants in either English or Swahili after a thorough explanation of the study’s purpose, risks, and benefits. All procedures were conducted in accordance with relevant guidelines and regulations for research involving human participants. Consent for publication Not applicable. Availability of data and materials The datasets generated and analyzed during the current study are are included in this published article and its supplementary information files. Competing interests The authors declare that they have no competing interests. Funding The authors did not receive funding to carry out this study. Authors' contributions UK served as the principal investigator, conceived the research idea, wrote the protocol, designed the study and data collection tools, evaluated the participants, collected the data, participated in its initial processing and was involved in writing the manuscript. LKK performed the data analysis and was involved in writing the manuscript. HOS and FOO served as secondary supervisors. They provided input in the topic, assisted in the research, their input ensuring that the study adhered to ethical standards and provided critical feedback during the development of the manuscript. LT was involved in data analysis and writing the manuscript. BKK was the primary supervisor working with the principal investigator to develop the topic, guiding the research process, reviewing drafts, and providing essential input regarding the study and manuscript. All authors read and approved the final manuscript. Acknowledgements The staff of University of Nairobi Dental school, Dental plaza and Kenyatta National Referral Hospital, Dental department for their help with this study. Mr. Thomas Kakairo, Mr. K’Owino Desmond Otieno and Ms. Grace Nabagala for their data processing and preliminary statistical work done. References JL. Resin composite—state of the art. Dent Mater. 2011;27(1):29–38. Bharti R, et al. Dental amalgam: An update. J Conserv Dent. 2010;13(4):204–8. Fisher J, et al. The Minamata Convention and the phase down of dental amalgam. Bull World Health Organ. 2018;96(6):436–8. Chan KHS, et al. Review: Resin Composite Filling. Materials. 2010;3:1228–43. 10.3390/ma3021228 . Roulet JF. Benefits and disadvantages of tooth-coloured alternatives to amalgam. J Dent. 1997;25(6):459–73. lie N. Resin composite restorative materials. Aust Dent J. 2011;56:59–66. Kassim BA, et al. EFFECT OF LIGHT CURING UNIT CHARACTERISTICS ON LIGHT INTENSITY OUTPUT, DEPTH OF CURE AND SURFACE MICRO-HARDNESS OF DENTAL RESIN COMPOSITE. East Afr Med J. 2013;90(9):288–96. Maktabi H, et al. Factors influencing success of radiant exposure in light-curing posterior dental composite in the clinical setting. Am J Dent. 2018;31(6):320–8. Loomans BAC, Hilton TJ. Extended Resin Composite Restorations: Techniques and Procedures. Oper Dent. 2016;41 S7:S58–67. Alshardan R, et al. Evaluation of Matrix Systems on the Proximal Contact of Class II Composite Restorations: A Systematic Review. Cureus. 2023;15(12):e50835. Anantula K, Vankayala B, Yadav SS. Proximal contact tightness of direct Class II composite resin restorations with various matrix systems: A systematic review. J Conserv Dent Endod. 2024;27(1):11–6. El-Shamy H, et al. Influence of volumetric shrinkage and curing light intensity on proximal contact tightness of class II resin composite restorations: in vitro study. Oper Dent. 2012;37(2):205–10. Peumans M, et al. Do condensable composites help to achieve better proximal contacts? Dent Mater. 2001;17(6):533–41. Türkün LS, Aktener BO, Ateş M. Clinical evaluation of different posterior resin composite materials: a 7-year report. Quintessence Int. 2003;34(6):418–26. Chang W-J, et al. Comparison of proximal in vitro tooth contacts in class II restorations with different restorative materials and cavity sizes using a new measurement device. J Mech Med Biology. 2015;15:1550057. Santos M et al. Multifactorial Contributors to the Longevity of Dental Restorations: An Integrated Review of Related Factors. Dent J (Basel), 2024. 12(9). Osiro O, Kisumbi B, Simila H. Selection of direct restorative and rooting filling materials by Kenyan dentists in 2014. East Afr Med J. 2016;93:500. El-Badrawy WA, et al. Evaluation of proximal contacts of posterior composite restorations with 4 placement techniques. J Can Dent Assoc. 2003;69(3):162–7. Saber NH et al. An Evaluation of Overhanging Dental Restorations’ Frequency and Localization in a Group of Yemeni People in Sana’a City – Yemen . Abolghasemzade F, Alaghehmand J. H, and u. R., The Reasons for Composite Restoration Replacement in Patients of the Restorative Department of Babol Dental School. Jentashapir J Cell Mol Biol, 2015. 6(6). Loomans BA, et al. A randomized clinical trial on proximal contacts of posterior composites. J Dent. 2006;34(4):292–7. Tolba ZO, Oraby E, Abd El PM, Aziz. Impact of matrix systems on proximal contact tightness and surface geometry in class II direct composite restoration in-vitro. BMC Oral Health. 2023;23(1):535. Wirsching E, et al. Influence of matrix systems on proximal contact tightness of 2- and 3-surface posterior composite restorations in vivo. J Dent. 2011;39(5):386–90. Sharafat A, et al. Analysis of Type of Proximal Contact Points of Porcelain Fused to Metal Crowns and Caries in Adjacent Teeth. Foundation Univ J Dentistry. 2023;3:104–10. Malempati R, et al. Revisiting Microleakage: Persistent Challenges in Restorative Dentistry. Int J Dent Mater. 2025;7:18–26. Truong VM, et al. Food Impaction in Dentistry: Revisited. Oral Health Prev Dent. 2023;21:229–42. Raskin A, et al. Clinical evaluation of a posterior composite 10-year report. J Dent. 1999;27(1):13–9. Additional Declarations No competing interests reported. Supplementary Files EvaluationofPCTdataset.xls Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 19 Mar, 2026 Reviews received at journal 22 Feb, 2026 Reviews received at journal 19 Feb, 2026 Reviews received at journal 18 Feb, 2026 Reviews received at journal 17 Feb, 2026 Reviews received at journal 17 Feb, 2026 Reviews received at journal 14 Feb, 2026 Reviewers agreed at journal 12 Feb, 2026 Reviewers agreed at journal 12 Feb, 2026 Reviewers agreed at journal 10 Feb, 2026 Reviewers agreed at journal 09 Feb, 2026 Reviewers agreed at journal 08 Feb, 2026 Reviewers agreed at journal 06 Feb, 2026 Reviewers agreed at journal 04 Feb, 2026 Reviewers invited by journal 04 Feb, 2026 Editor invited by journal 12 Jan, 2026 Editor assigned by journal 10 Jan, 2026 Submission checks completed at journal 10 Jan, 2026 First submitted to journal 08 Jan, 2026 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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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {\"props\":{\"pageProps\":{\"initialData\":{\"identity\":\"rs-8547564\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Research Article\",\"associatedPublications\":[],\"authors\":[{\"id\":587763714,\"identity\":\"1bf3a71b-9d46-40a7-9e0e-aa8df48bb374\",\"order_by\":0,\"name\":\"Umaru Kizito\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Makerere University\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Umaru\",\"middleName\":\"\",\"lastName\":\"Kizito\",\"suffix\":\"\"},{\"id\":587763715,\"identity\":\"7b67bd9c-3f7a-4bdf-8f4b-ec7fd128a7e4\",\"order_by\":1,\"name\":\"Lois Keren Kisakye\",\"email\":\"data:image/png;base64,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\",\"orcid\":\"\",\"institution\":\"Makerere University\",\"correspondingAuthor\":true,\"prefix\":\"\",\"firstName\":\"Lois\",\"middleName\":\"Keren\",\"lastName\":\"Kisakye\",\"suffix\":\"\"},{\"id\":587763716,\"identity\":\"b1e626c1-60f2-45cc-925e-6931834998b5\",\"order_by\":2,\"name\":\"Hazel Orengo Simila\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Nairobi\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Hazel\",\"middleName\":\"Orengo\",\"lastName\":\"Simila\",\"suffix\":\"\"},{\"id\":587763717,\"identity\":\"809b29e2-5120-4e9e-ba47-9246b554d7af\",\"order_by\":3,\"name\":\"Fred Odera Otieno\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Nairobi\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Fred\",\"middleName\":\"Odera\",\"lastName\":\"Otieno\",\"suffix\":\"\"},{\"id\":587763718,\"identity\":\"fb501724-c326-439a-a60f-180608309466\",\"order_by\":4,\"name\":\"Lincoln Abraham Tentena\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Makerere University\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Lincoln\",\"middleName\":\"Abraham\",\"lastName\":\"Tentena\",\"suffix\":\"\"},{\"id\":587763719,\"identity\":\"74af5a37-b544-44e2-9160-d8850455ebd1\",\"order_by\":5,\"name\":\"Bernina Kyale Kisumbi\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"University of Nairobi\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Bernina\",\"middleName\":\"Kyale\",\"lastName\":\"Kisumbi\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2026-01-08 06:23:28\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-8547564/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-8547564/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":102189204,\"identity\":\"f8a264e7-4380-4ce8-9ec5-5bb04c462154\",\"added_by\":\"auto\",\"created_at\":\"2026-02-09 08:55:10\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":19974,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eDistribution of Class II Restorations\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage1.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8547564/v1/49d824bd4bbefda6a937b301.png\"},{\"id\":102189520,\"identity\":\"3772805b-8299-4626-ad3a-5ef7050949b8\",\"added_by\":\"auto\",\"created_at\":\"2026-02-09 08:55:59\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":22311,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eProximal contact tightness of Class II RCRs\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage2.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8547564/v1/ee63283524c8b9bb07870de1.png\"},{\"id\":102189090,\"identity\":\"12e69fab-b0da-446e-a1ef-4ec3222bd786\",\"added_by\":\"auto\",\"created_at\":\"2026-02-09 08:54:18\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":35401,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eDistribution of proximal contact tightness among Class II restorations in 3 facilities\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage3.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8547564/v1/d9bf4b102a2af760409bbf7b.png\"},{\"id\":102189496,\"identity\":\"177beddf-d52a-4949-9920-26137e1eabbd\",\"added_by\":\"auto\",\"created_at\":\"2026-02-09 08:55:52\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":35594,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eDistribution of proximal contact tightness among class II restorations by tooth type\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage4.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8547564/v1/834a06622512ae48bc80c760.png\"},{\"id\":102297581,\"identity\":\"c3632e87-96ae-4ee5-a50a-ea3e3a307cf5\",\"added_by\":\"auto\",\"created_at\":\"2026-02-10 10:28:22\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":999840,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8547564/v1/c12aaba2-657c-4762-9115-b46e7234c4da.pdf\"},{\"id\":102189086,\"identity\":\"7999a87d-cfd4-4297-8143-2a671d666611\",\"added_by\":\"auto\",\"created_at\":\"2026-02-09 08:54:15\",\"extension\":\"xls\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"supplement\",\"size\":216064,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"EvaluationofPCTdataset.xls\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8547564/v1/a158bd1e153c7fabcb738b81.xls\"}],\"financialInterests\":\"No competing interests reported.\",\"formattedTitle\":\"Evaluation of Proximal Contact Integrity and Associated Factors in Posterior Resin Composite Restorations: A Cross-sectional Study in Nairobi, Kenya\",\"fulltext\":[{\"header\":\"BACKGROUND\",\"content\":\"\\u003cp\\u003eDental resin composite, a tooth-coloured restorative material, has been used for more than half a century in the treatment of dental caries affecting both anterior and posterior teeth [\\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e]. In the past, dental amalgam was the preferred material for posterior restorations [\\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2\\u003c/span\\u003e]. However, growing patient demand for aesthetic solutions, the favourable properties of composite restorations, and the global Minamata convention on mercury advocating for an amalgam phase-down by individual countries have led to an increased preference for direct posterior resin composite restorations (RCRs) [\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e3\\u003c/span\\u003e]. This transition underscores the need for careful assessment of RCR performance, particularly in high stress-bearing posterior areas.\\u003c/p\\u003e \\u003cp\\u003eThe placement of RCRs is highly technique sensitive as it requires the balance of multiple conditions for achieving long-lasting restorations [\\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e4\\u003c/span\\u003e]. Moisture control is essential because moisture can compromise bonding, so methods like rubber dam isolation are recommended [\\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e5\\u003c/span\\u003e]. The cavity should be modified to expose more enamel for stronger bonding, and the composite should be placed incrementally to reduce polymerization shrinkage [\\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e5\\u003c/span\\u003e]. Proper conditioning of enamel and dentine helps ensure good adhesion. Effective light curing is also critical, as the intensity and exposure time of the curing unit affect the composite\\u0026rsquo;s degree of conversion and hardness. Aesthetic goals such as colour match, stable shade, smooth finish, long-term gloss and good polishability also need attention [\\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e5\\u003c/span\\u003e]. Long-term success depends on accurate anatomical contouring and well-sealed margins to prevent leakage and discoloration [\\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e6\\u003c/span\\u003e].\\u003c/p\\u003e \\u003cp\\u003eFor Class II cavities, which involve the mesial-occlusal (MO), distal-occlusal (DO), and mesial-occlusal-distal (MOD) proximal surfaces, reconstruction of proximal contacts in a specialized manner is crucial to prevent fractures and preserve tooth structure [\\u003cspan additionalcitationids=\\\"CR8\\\" citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e7\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e9\\u003c/span\\u003e]. Literature shows that achieving tight proximal contacts with Class II composites remains a challenge: in one systematic review of contact outcomes, only about 6% of restorations had tight contacts while open contacts occurred in 61.6% of cases [\\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e10\\u003c/span\\u003e]. PCT is one of the specialized parameters assessed for Class II restorations [\\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e]. Matrix systems play a critical role in establishing proper proximal morphology. When correctly positioned, the matrix complex enables accurate reconstruction of the proximal wall and reduces the risk of overhangs or open contacts [\\u003cspan additionalcitationids=\\\"CR13\\\" citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e12\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e14\\u003c/span\\u003e]. Failure to establish an adequate proximal contact is a commonly reported complication and a significant factor in RCR failure. It can lead to localized periodontitis and gingivitis due to food impaction [\\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e]. In clinical settings, PCT is conventionally assessed using the tactile method with dental floss. The contact is ideal if the floss passes through with a \\\"snap\\\" [\\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e15\\u003c/span\\u003e]. Assessment includes recording whether contacts are too tight (difficult to place/withdraw), tight (reasonable placement/withdrawal), loose, or open (no resistance) [\\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e15\\u003c/span\\u003e].\\u003c/p\\u003e \\u003cp\\u003eDespite the growing indication for RCRs globally, there is a noted burden on healthcare systems due to the failure of posterior RCRs, often leading to replacement or complex treatments [\\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e16\\u003c/span\\u003e]. In Nairobi, Kenya, where RCR use is increasing [\\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e17\\u003c/span\\u003e], local data regarding the longevity, failure rates, and specific technical failures, such as deficiencies in proximal contact integrity, are lacking. This research therefore aimed to address this gap by assessing the integrity of proximal contacts in Class II posterior RCRs placed in selected institutions in Nairobi, Kenya, thereby contributing to the comprehensive understanding of RCR performance in this region. The core objective of the parent study was to evaluate the performance of direct posterior resin composite restorations placed over a 5-year period in Nairobi, Kenya.\\u003c/p\\u003e\"},{\"header\":\"METHODS\",\"content\":\"\\u003cdiv id=\\\"Sec3\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eStudy aim and design\\u003c/h2\\u003e \\u003cp\\u003eThe aim of this study was to evaluate proximal contact tightness and associated factors of Class II posterior resin composite restorations placed over a 5-year period at University of Nairobi Dental School, University of Nairobi Dental Plaza, and Kenyatta National Hospital Dental Department in Nairobi, Kenya. This study utilized a cross-sectional study design.\\u003c/p\\u003e \\u003c/div\\u003e\\n\\u003ch3\\u003eStudy setting\\u003c/h3\\u003e\\n\\u003cp\\u003eThis research study was conducted in Nairobi County, Kenya across 3 distinct dental clinic al settings conveniently sampled for their institutional diversity: the \\u003cb\\u003eUniversity of Nairobi Dental School (UoNDS)\\u003c/b\\u003e, a teaching hospital; the \\u003cb\\u003eUniversity of Nairobi Dental Plaza (UoNDP)\\u003c/b\\u003e, a private facility; and the \\u003cb\\u003eKenyatta National Hospital Dental Department (KNHDD)\\u003c/b\\u003e, a public hospital.\\u003c/p\\u003e\\n\\u003ch3\\u003eStudy Population\\u003c/h3\\u003e\\n\\u003cp\\u003eThe study population consisted of patients with posterior RCRs placed at the three selected sites between 2014 and 2019.\\u003c/p\\u003e\\n\\u003ch3\\u003eSample Size Determination and Sampling\\u003c/h3\\u003e\\n\\u003cp\\u003eThe target sample size was initially calculated using Kish Leslie\\u0026rsquo;s method for a single proportion, assuming a 50% prevalence of posterior RCRs. The final calculated sample size, adjusted for a population estimate of 1000, was 278 RCRs. This total was divided equally, aiming for 93 restorations per study area and 19 per year of study per site. Ultimately, a total of 286 posterior RCRs distributed among 95 participants were examined. While the parent study initially examined 286 restorations from 95 participants including class I, II, and V restorations, a specialized subset of 159 Class II RCRs was selected for this investigation into proximal contact integrity. The study sites were selected using convenient sampling. Participants were identified through patient records and daily work registers. A stratified random sampling approach was employed to select participants, based on the year of placement of the RCR and the specific facility.\\u003c/p\\u003e\\n\\u003ch3\\u003eSelection Criteria\\u003c/h3\\u003e\\n\\u003cp\\u003e \\u003cb\\u003eInclusion Criteria\\u003c/b\\u003e:\\u003c/p\\u003e \\u003cp\\u003e \\u003col\\u003e \\u003cspan\\u003e \\u003cli\\u003e \\u003cp\\u003eParticipants who consented to the study.\\u003c/p\\u003e \\u003c/li\\u003e \\u003c/span\\u003e \\u003cspan\\u003e \\u003cli\\u003e \\u003cp\\u003eParticipants who had class II direct posterior composite restorations on permanent posterior teeth placed between 2014 and 2019 with proper records.\\u003c/p\\u003e \\u003c/li\\u003e \\u003c/span\\u003e \\u003cspan\\u003e \\u003cli\\u003e \\u003cp\\u003eParticipants above 18 years of age.\\u003c/p\\u003e \\u003c/li\\u003e \\u003c/span\\u003e \\u003c/ol\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eExclusion Criteria\\u003c/b\\u003e:\\u003c/p\\u003e \\u003cp\\u003e \\u003col\\u003e \\u003cspan\\u003e \\u003cli\\u003e \\u003cp\\u003eParticipants with incomplete records about the RCRs.\\u003c/p\\u003e \\u003c/li\\u003e \\u003c/span\\u003e \\u003cspan\\u003e \\u003cli\\u003e \\u003cp\\u003eParticipants who did not consent.\\u003c/p\\u003e \\u003c/li\\u003e \\u003c/span\\u003e \\u003cspan\\u003e \\u003cli\\u003e \\u003cp\\u003eIndirect RCRs as per dental records.\\u003c/p\\u003e \\u003c/li\\u003e \\u003c/span\\u003e \\u003cspan\\u003e \\u003cli\\u003e \\u003cp\\u003e4. Posterior RCRs on deciduous teeth or permanent teeth apart from premolars and molars.\\u003c/p\\u003e \\u003c/li\\u003e \\u003c/span\\u003e \\u003c/ol\\u003e \\u003c/p\\u003e \\u003cdiv id=\\\"Sec8\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eData Collection Instruments and Techniques\\u003c/h2\\u003e \\u003cp\\u003eAfter obtaining approval to access patient records, a list of individuals who received posterior composite restorations from 2014 to 2019 was compiled. Ninety-five eligible participants were recruited, contributing a total of 286 restorations evenly distributed across the study sites. Participants were contacted by phone using numbers from their dental records and scheduled for appointments based on their availability and that of the lead investigator. Each participant received a one-hour appointment. Written informed consent in English or Swahili was obtained after the study was fully explained and any questions addressed. All personal and clinical information was handled confidentially, and participation was entirely voluntary.\\u003c/p\\u003e \\u003c/div\\u003e\\n\\u003ch3\\u003eClinical Examination\\u003c/h3\\u003e\\n\\u003cp\\u003eClinical examination was performed in a clinical setting utilizing a dental mirror, dental explorer, and a WHO periodontal probe.\\u003c/p\\u003e\\n\\u003ch3\\u003eClinical Data Collection Tool (USPHS)\\u003c/h3\\u003e\\n\\u003cp\\u003eThe clinical performance of the posterior RCRs was evaluated using a modified version of the United States Public Health Survey (USPHS) tool for tooth-coloured restorations.\\u003c/p\\u003e \\u003cdiv id=\\\"Sec11\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eProximal Contact Tightness Assessment\\u003c/h2\\u003e \\u003cp\\u003eTo measure proximal tightness for Class II composite restorations, waxed single strand dental floss, approximately 20 cm in length, was utilized. Observations were recorded to establish whether the contacts were:\\u003c/p\\u003e \\u003cp\\u003e \\u003cul\\u003e \\u003cli\\u003e \\u003cp\\u003eTight: Reasonable placement and withdrawal of floss\\u003c/p\\u003e \\u003c/li\\u003e \\u003cli\\u003e \\u003cp\\u003eLoose: Minimal resistance to floss\\u003c/p\\u003e \\u003c/li\\u003e \\u003cli\\u003e \\u003cp\\u003eOpen: No resistance on placement and withdrawal of floss.\\u003c/p\\u003e \\u003c/li\\u003e \\u003c/ul\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec12\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eData Validity and Reliability\\u003c/h2\\u003e \\u003cp\\u003eIntra-examiner reliability was assessed using Cohen\\u0026rsquo;s Kappa, yielding a value of 0.90, which demonstrated perfect reliability and validity.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec13\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eData Analysis\\u003c/h2\\u003e \\u003cp\\u003eData was cleaned and analysed using STATA version 19. Categorical variables were summarized with proportions and percentages. Chi-square tests were used to explore associations between PCT and factors such as secondary caries, tooth type, dental facility and restoration surface. Multinomial regression was used to determine factors associated with PCT. Factors to be included in the multivariate analysis were selected at bivariate analysis at a p - value\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.2. Interaction terms were formed between significant variables, and a likelihood ratio test was used to check for the presence of interaction. There was no significant interaction. Stepwise estimation was done to maintain only significant variables. Thereafter, the data was checked for confounding with a percentage change greater than 10% used to confirm the presence of a confounder.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec14\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eEthical Considerations and Consent\\u003c/h2\\u003e \\u003cp\\u003e Written informed consent was sought from participants in either Swahili or English after thorough explanation of the study, its risks, and benefits. Ethical approval was obtained from The Kenyatta National Hospital-University of Nairobi Ethics and Research Committee \\u003cb\\u003e(Protocol No. P760/08/2019).\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"RESULTS\",\"content\":\"\\u003cp\\u003eThe study examined a total of 159 Class II RCRs. The USPHS clinical evaluation tool was used, with modifications made for Class II composite restorations to measure proximal tightness. This assessment focused on restorations placed on mesial-occlusal/distal-occlusal (MO/DO) and mesial-occlusal-distal (MOD) surfaces.\\u003c/p\\u003e \\u003cdiv id=\\\"Sec16\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eDistribution of Class II Restorations according to tooth surface\\u003c/h2\\u003e \\u003cp\\u003eThe MO/DO surfaces dominated the restoration surfaces examined at 145 (91.2%) of all RCRs, while MOD restorations accounted for 14 (8.8%). This is represented in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e below.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec17\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eProximal Contact Tightness Findings\\u003c/h2\\u003e \\u003cp\\u003eProximal contact tightness analysis was conducted on 139 of the 159 class II RCRs (MO/DO and MOD), given that 20 of the class II restorations could not be assessed due to the absence of adjacent teeth. A sizable majority of these restorations, 79 (56.8%), were found to have tight contacts. However, a total of 60 (43.2%) were found to have unacceptable proximal tightness, defined as having loose or open contacts. Of these 60, 31(51.7%) were loose whereas 29 (48.3%) were open. The findings from proximal contact tightness analysis are represented in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e below.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec18\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eDistribution of PCT among facilities\\u003c/h2\\u003e \\u003cp\\u003eOf all 139 class II RCRs assessed for proximal contact tightness, 45 (32.4%) were done at UoNDP while 50 (35.9%) and 44 (31.7%) were done at UoNDS and KNHDD respectively. A significantly higher proportion (75%) of restorations at KNHDD exhibited unacceptable (loose and open) contacts. In comparison, unacceptable contacts were observed in 26.7% of class II restorations at UoNDP and 30% at UoNDS. This distribution is represented in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e below.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec19\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eDistribution of PCT among tooth type\\u003c/h2\\u003e \\u003cp\\u003eAmong the 139 class II RCRs assessed for proximal contact tightness, 67 were molars and 72 were premolars. A slightly higher proportion of molars 44.8% of had unacceptable contacts, defined as loose or open while 41.7% of premolars had unacceptable contacts. These findings are shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e below.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec20\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eAssociation of PCT with other factors\\u003c/h2\\u003e \\u003cp\\u003eChi-square tests showed significant association between proximal contact tightness and secondary caries (χ\\u0026sup2; = 8.05, p\\u0026thinsp;=\\u0026thinsp;0.018), as well as the facility at which the restoration was placed (χ\\u0026sup2;= 30.77, p\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.001). The results of the chi-square tests are shown in Table \\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e below.\\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\\u003eChi-square tests of association between PCT and other factors\\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=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eFactor\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eChi-square value (χ\\u0026sup2;)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003ep-value\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eRestoration surface\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.27\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.875\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eSecondary caries\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e8.05\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.018\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eFacility\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e30.77\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eTooth type\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.74\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.691\\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\\u003eMultivariate analysis included the surface of the restoration, tooth type, secondary caries and the facility at which the restoration was placed. The presence of secondary caries showed a significant association with proximal contact tightness when loose contacts were compared to tight contacts (RRR\\u0026thinsp;=\\u0026thinsp;6.08, p\\u0026thinsp;=\\u0026thinsp;0.02, 95% CI 1.94\\u0026ndash;19.06) but showed no significant association among open contacts. Among the facilities, KNH showed a significant association with proximal contact tightness when both open contacts (RRR\\u0026thinsp;=\\u0026thinsp;4.71, p\\u0026thinsp;=\\u0026thinsp;0.008, 95% CI 1.50\\u0026ndash;14.80) and loose contacts (RRR\\u0026thinsp;=\\u0026thinsp;33.88, p\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.001, 95% CI 6.15\\u0026ndash;186.61) were compared to tight contacts. The results for multivariate analysis are shown in Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e below.\\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\\u003eMultivariate analysis of factors associated with PCT\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"5\\\"\\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=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c5\\\" colnum=\\\"5\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eFactor\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003ePCT\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eaRRR\\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\\u003eP-value\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSecondary caries\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e\\u0026nbsp;\\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e\\u0026nbsp;\\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e\\u0026nbsp;\\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c5\\\"\\u003e\\u0026nbsp;\\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003ePresent\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eOpen vs Tight\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e1.84\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e0.55\\u0026ndash;6.20\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.326\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003ePresent\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eLoose vs Tight\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e6.08\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e1.94\\u0026ndash;19.06\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.002\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eFacility\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c5\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eKNHDD\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eOpen vs Tight\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e4.71\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e1.50\\u0026ndash;14.80\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.008\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eKNHDD\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eLoose vs Tight\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e33.88\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e6.15\\u0026ndash;186.61\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eUoNDS\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eOpen vs Tight\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.45\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e0.12\\u0026ndash;1.66\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.232\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eUoNDS\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eLoose vs Tight\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e3.99\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e0.76\\u0026ndash;20.89\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e0.101\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003ctfoot\\u003e \\u003ctr\\u003e\\u003ctd colspan=\\\"5\\\"\\u003eaRRR\\u0026thinsp;=\\u0026thinsp;adjusted relative risk ratio\\u003c/td\\u003e\\u003c/tr\\u003e \\u003c/tfoot\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"DISCUSSION\",\"content\":\"\\u003cp\\u003eThe findings from this study provide novel insights into PCT among class II RCRs in a Kenyan dental setting, revealing a high prevalence of unacceptable contacts (43.2%) among 139 assessable restorations. Tight contacts predominated at 56.8%, yet the substantial proportion of loose (22.3%) and open (20.9%) contacts underscores a critical quality gap in the placement of posterior RCRs. This observation mirrors concerns reported in the previous literature about the difficulty of consistently forming optimal contacts with composite materials. El-Badrawy et al found that a high proportion of Class II composite restorations had open or inadequate proximal contacts depending on placement technique, in contrast to amalgam restorations that more frequently produced acceptable contacts[\\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e18\\u003c/span\\u003e]. Predominantly MO/DO surfaces (91.2%) were evaluated, reflecting common clinical practice reports from literature [\\u003cspan citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e19\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e20\\u003c/span\\u003e], while the inability to assess 20 restorations (12.6%) due to missing adjacent teeth highlights a real-world challenge in PCT evaluation. Tooth type yielded comparable unacceptable rates (44.8% for molars and 41.7% for premolars), even with a chi-square test showing no significant difference between the two (χ\\u0026sup2;=0.74, p\\u0026thinsp;=\\u0026thinsp;0.691), therefore suggesting that technique rather than anatomy drove outcomes here.\\u003c/p\\u003e \\u003cp\\u003eFacility-level disparities were striking, with KNHDD showing 75% unacceptable contacts compared to 26.7% at UoNDP and 30% at UoNDS. Multivariate analysis confirmed KNHDD\\u0026rsquo;s strong association with both open (aRRR\\u0026thinsp;=\\u0026thinsp;4.71, 95% CI: 1.50\\u0026ndash;14.80, p\\u0026thinsp;=\\u0026thinsp;0.008) and loose contacts (aRRR\\u0026thinsp;=\\u0026thinsp;33.88, 95% CI: 6.15\\u0026ndash;186.61, p\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.001) compared to tight contacts. This trend may indicate an operator-related factor, where clinicians in Kenya might deliberately or inadvertently create open margins, possibly under the belief that it enhances oral hygiene access [\\u003cspan citationid=\\\"CR21\\\" class=\\\"CitationRef\\\"\\u003e21\\u003c/span\\u003e] or due to limitations in matrix systems used[\\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e22\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e23\\u003c/span\\u003e], particularly in public dental clinics or teaching environments.\\u003c/p\\u003e \\u003cp\\u003eSecondary caries showed a significant bivariate association with PCT (χ\\u0026sup2;=8.05, p\\u0026thinsp;=\\u0026thinsp;0.018) and persisted for loose contacts compared to tight contacts at multivariate analysis. (RRR\\u0026thinsp;=\\u0026thinsp;6.08, 95%CI: 1.94\\u0026ndash;19.06, p\\u0026thinsp;=\\u0026thinsp;0.02). These findings align with those reported by Sharafat et al who demonstrated a strong association between defective proximal contacts and caries development in adjacent teeth [\\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e24\\u003c/span\\u003e]. Notably, no such link was shown for open contacts. This difference may reflect variations in plaque retention, food impaction, and challenges in interproximal cleaning associated with loose contacts, or even a limited sample size. Loose contacts facilitate microbial ingress accelerating demineralization at restoration margins, a well-documented pathway in studies [\\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e25\\u003c/span\\u003e]. Inadequate contacts also allow food impaction in the interdental spaces, the consequences of which include localized gingival inflammation and periodontitis, which can exacerbate tissue destruction and ultimately precipitate restoration failure [\\u003cspan citationid=\\\"CR26\\\" class=\\\"CitationRef\\\"\\u003e26\\u003c/span\\u003e]. Patients may require more frequent recalls, repairs, or even premature replacement of restorations, imposing additional costs and patient discomfort.\\u003c/p\\u003e \\u003cp\\u003eProximal contact tightness is paramount for the longevity and success of restorations as it directly influences the functional and aesthetic outcomes, as well as the long-term viability of the restoration [\\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e]. Indeed, a longitudinal study with up to 10 years of follow-up identified loss of proximal contact as a leading cause of failure for posterior composite restorations [\\u003cspan citationid=\\\"CR27\\\" class=\\\"CitationRef\\\"\\u003e27\\u003c/span\\u003e]. The observed deficiencies in proximal contact integrity in this study setting suggest that there may be a lack of understanding or application of the principles of adhesion and contact mechanics during the restorative process. This calls for enhanced educational initiatives aimed at equipping practitioners with the skills necessary to optimize the placement of RCRs, thereby reducing the risk of failure. Furthermore, ongoing professional development programs could be instrumental in disseminating the latest research findings and techniques in restorative dentistry.\\u003c/p\\u003e \\u003cp\\u003eThese findings provide a useful baseline for future research on the performance of resin composite restorations in Kenya. The lack of local evidence on longevity and failure rates has limited understanding of their clinical behaviour, and this study helps fill that gap. Further research could investigate specific operator techniques associated with contact failures, explore motivational or educational factors influencing clinical decisions around contact tightness, and evaluate interventions like matrix system enhancements or restorative material innovations that improve proximal contact integrity. Additionally, longitudinal follow-up studies examining the association between proximal contact integrity and other clinical outcomes, including caries recurrence, periodontal health, and patient satisfaction, would provide valuable comprehensive insights to guide clinical practice and policy planning in Kenya and similar settings.\\u003c/p\\u003e \\u003cdiv id=\\\"Sec22\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eStrengths and Limitations\\u003c/h2\\u003e \\u003cp\\u003e The research directly addresses the noted lack of local data regarding deficiencies in PCT, one of the specialized parameters and a key determinant of restoration success for Class II restorations using RCRs, in Nairobi, Kenya. The cross-sectional design of the study however presented a limitation in that it precluded the establishment of a cause-and-effect relationship regarding PCT and restoration failure.\\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"CONCLUSIONS\",\"content\":\"\\u003cp\\u003eThe study demonstrates that the prevalence of inadequate proximal contacts (43.2%) is considerably high among Class II posterior resin composite restorations (RCRs) in Nairobi, Kenya. This underscores a critical quality gap in the clinical performance of these restorations, particularly within public hospital settings where unacceptable contacts were significantly more frequent. Because inadequate proximal integrity is strongly associated with secondary caries and can lead to localized periodontal issues and premature restoration failure, establishing proper contact tightness is paramount for long-term clinical success. These findings suggest a need for enhanced educational initiatives and professional development to equip dental practitioners in Kenya with better skills in adhesion and contact mechanics. Furthermore, this research provides a vital baseline for future longitudinal studies to evaluate the impact of proximal contact integrity on caries recurrence and patient satisfaction in the region.\\u003c/p\\u003e\"},{\"header\":\"Abbreviations\",\"content\":\"\\u003cdiv class=\\\"DefinitionList\\\"\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eaRRR\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eAdjusted relative risk ratio\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eCI\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eConfidence interval\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eDO\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eDistal-occlusal\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eKNHDD\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eKenyatta National Hospital Dental Department\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eMO\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eMesial-occlusal\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eMOD\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eMesial-occlusal-distal\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003ePCT\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eProximal contact tightness\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eRCRs\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eResin composite restorations\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eUoNDS\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eUniversity of Nairobi Dental School\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eUoNDP\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eUniversity of Nairobi Dental Plaza\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eUSPHS\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eUnited States Public Health Survey\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e \\u003cdiv class=\\\"Term\\\"\\u003eWHO\\u003c/div\\u003e \\u003cdiv class=\\\"Description\\\"\\u003e \\u003cp\\u003eWorld Health Organization\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/div\\u003e \\u003c/div\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eEthics approval and consent to participate\\u003c/strong\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eThe study received ethical clearance and approval from the Kenyatta National Hospital-University of Nairobi Ethics and Research Committee (Protocol No. P760/08/2019). Participation was entirely voluntary, and written informed consent was obtained from all participants in either English or Swahili after a thorough explanation of the study\\u0026rsquo;s purpose, risks, and benefits. All procedures were conducted in accordance with relevant guidelines and regulations for research involving human participants.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConsent for publication\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eNot applicable.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAvailability of data and materials\\u003c/strong\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eThe datasets generated and analyzed during the current study are \\u0026nbsp;are included in this published article and its supplementary information files.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eCompeting interests\\u003c/strong\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors declare that they have no competing interests.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eFunding\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors did not receive funding to carry out this study.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAuthors\\u0026apos; contributions\\u003c/strong\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eUK served as the principal investigator, conceived the research idea, wrote the protocol, designed the study and data collection tools, evaluated the participants, collected the data, participated in its initial processing and was involved in writing the manuscript.\\u003c/p\\u003e\\n\\u003cp\\u003eLKK performed the data analysis and was involved in writing the manuscript.\\u003c/p\\u003e\\n\\u003cp\\u003eHOS and FOO served as secondary supervisors. They provided input in the topic, assisted in the research, their input ensuring that the study adhered to ethical standards and provided critical feedback during the development of the manuscript.\\u003c/p\\u003e\\n\\u003cp\\u003eLT was involved in data analysis and writing the manuscript.\\u003c/p\\u003e\\n\\u003cp\\u003eBKK was the primary supervisor working with the principal investigator to develop the topic, guiding the research process, reviewing drafts, and providing essential input regarding the study and manuscript.\\u003c/p\\u003e\\n\\u003cp\\u003eAll authors read and approved the final manuscript.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAcknowledgements\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe staff of University of Nairobi Dental school, Dental plaza and Kenyatta National Referral\\u003c/p\\u003e\\n\\u003cp\\u003eHospital, Dental department for their help with this study.\\u003c/p\\u003e\\n\\u003cp\\u003eMr. Thomas Kakairo, Mr. K\\u0026rsquo;Owino Desmond Otieno and Ms. Grace Nabagala for their data\\u003c/p\\u003e\\n\\u003cp\\u003eprocessing and preliminary statistical work done.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\u003cli\\u003e\\u003cspan\\u003eJL. Resin composite\\u0026mdash;state of the art. Dent Mater. 2011;27(1):29\\u0026ndash;38.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eBharti R, et al. Dental amalgam: An update. J Conserv Dent. 2010;13(4):204\\u0026ndash;8.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eFisher J, et al. The Minamata Convention and the phase down of dental amalgam. Bull World Health Organ. 2018;96(6):436\\u0026ndash;8.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eChan KHS, et al. Review: Resin Composite Filling. Materials. 2010;3:1228\\u0026ndash;43. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.3390/ma3021228\\u003c/span\\u003e\\u003cspan address=\\\"10.3390/ma3021228\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eRoulet JF. Benefits and disadvantages of tooth-coloured alternatives to amalgam. J Dent. 1997;25(6):459\\u0026ndash;73.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003elie N. Resin composite restorative materials. Aust Dent J. 2011;56:59\\u0026ndash;66.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eKassim BA, et al. EFFECT OF LIGHT CURING UNIT CHARACTERISTICS ON LIGHT INTENSITY OUTPUT, DEPTH OF CURE AND SURFACE MICRO-HARDNESS OF DENTAL RESIN COMPOSITE. East Afr Med J. 2013;90(9):288\\u0026ndash;96.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eMaktabi H, et al. Factors influencing success of radiant exposure in light-curing posterior dental composite in the clinical setting. Am J Dent. 2018;31(6):320\\u0026ndash;8.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eLoomans BAC, Hilton TJ. Extended Resin Composite Restorations: Techniques and Procedures. Oper Dent. 2016;41 S7:S58\\u0026ndash;67.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eAlshardan R, et al. Evaluation of Matrix Systems on the Proximal Contact of Class II Composite Restorations: A Systematic Review. Cureus. 2023;15(12):e50835.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eAnantula K, Vankayala B, Yadav SS. Proximal contact tightness of direct Class II composite resin restorations with various matrix systems: A systematic review. J Conserv Dent Endod. 2024;27(1):11\\u0026ndash;6.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eEl-Shamy H, et al. Influence of volumetric shrinkage and curing light intensity on proximal contact tightness of class II resin composite restorations: in vitro study. Oper Dent. 2012;37(2):205\\u0026ndash;10.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003ePeumans M, et al. Do condensable composites help to achieve better proximal contacts? Dent Mater. 2001;17(6):533\\u0026ndash;41.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eT\\u0026uuml;rk\\u0026uuml;n LS, Aktener BO, Ateş M. Clinical evaluation of different posterior resin composite materials: a 7-year report. Quintessence Int. 2003;34(6):418\\u0026ndash;26.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eChang W-J, et al. Comparison of proximal in vitro tooth contacts in class II restorations with different restorative materials and cavity sizes using a new measurement device. J Mech Med Biology. 2015;15:1550057.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eSantos M et al. Multifactorial Contributors to the Longevity of Dental Restorations: An Integrated Review of Related Factors. Dent J (Basel), 2024. 12(9).\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eOsiro O, Kisumbi B, Simila H. Selection of direct restorative and rooting filling materials by Kenyan dentists in 2014. East Afr Med J. 2016;93:500.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eEl-Badrawy WA, et al. Evaluation of proximal contacts of posterior composite restorations with 4 placement techniques. J Can Dent Assoc. 2003;69(3):162\\u0026ndash;7.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eSaber NH et al. \\u003cem\\u003eAn Evaluation of Overhanging Dental Restorations\\u0026rsquo; Frequency and Localization in a Group of Yemeni People in Sana\\u0026rsquo;a City \\u0026ndash; Yemen\\u003c/em\\u003e.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eAbolghasemzade F, Alaghehmand J. H, and u. R., The Reasons for Composite Restoration Replacement in Patients of the Restorative Department of Babol Dental School. Jentashapir J Cell Mol Biol, 2015. 6(6).\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eLoomans BA, et al. A randomized clinical trial on proximal contacts of posterior composites. J Dent. 2006;34(4):292\\u0026ndash;7.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTolba ZO, Oraby E, Abd El PM, Aziz. Impact of matrix systems on proximal contact tightness and surface geometry in class II direct composite restoration in-vitro. BMC Oral Health. 2023;23(1):535.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eWirsching E, et al. Influence of matrix systems on proximal contact tightness of 2- and 3-surface posterior composite restorations in vivo. J Dent. 2011;39(5):386\\u0026ndash;90.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eSharafat A, et al. Analysis of Type of Proximal Contact Points of Porcelain Fused to Metal Crowns and Caries in Adjacent Teeth. Foundation Univ J Dentistry. 2023;3:104\\u0026ndash;10.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eMalempati R, et al. Revisiting Microleakage: Persistent Challenges in Restorative Dentistry. Int J Dent Mater. 2025;7:18\\u0026ndash;26.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTruong VM, et al. Food Impaction in Dentistry: Revisited. Oral Health Prev Dent. 2023;21:229\\u0026ndash;42.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eRaskin A, et al. Clinical evaluation of a posterior composite 10-year report. J Dent. 1999;27(1):13\\u0026ndash;9.\\u003c/span\\u003e\\u003c/li\\u003e\\u003c/ol\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":false,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":true,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"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\":\"Resin composite restorations, Proximal contact tightness, Class II restorations, Nairobi, Kenya, USPHS\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-8547564/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-8547564/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003ch2\\u003eBackground\\u003c/h2\\u003e \\u003cp\\u003eThe global shift from dental amalgam to direct posterior resin composite restorations (RCRs), driven by aesthetic demands and the Minamata Convention, has increased the need to evaluate their clinical performance. Establishing proper proximal contact tightness (PCT) in Class II restorations is a critical, technique-sensitive parameter required to prevent food impaction, periodontal disease, and restoration failure. In Nairobi, Kenya, there is a lack of local data regarding technical failures like deficiencies in proximal contact integrity. This study aimed to evaluate the proximal contact tightness of Class II posterior RCRs placed over a five-year period in selected dental institutions in Nairobi.\\u003c/p\\u003e\\u003ch2\\u003eMethods\\u003c/h2\\u003e \\u003cp\\u003eA cross-sectional study was conducted at three sites: a private facility (UoNDP), a teaching hospital (UoNDS), and a public hospital (KNHDD). A total of 159 Class II RCRs placed between 2014 and 2019 were selected for clinical examination. PCT was assessed using a tactile method with dental floss and categorized as tight, too tight, loose, or open, utilizing a modified United States Public Health Survey (USPHS) tool. Data were analyzed using STATA version 19, employing Chi-square tests and multivariate analysis to identify associated factors.\\u003c/p\\u003e\\u003ch2\\u003eResults\\u003c/h2\\u003e \\u003cp\\u003eOf the 139 assessable restorations (20 were excluded due to missing adjacent teeth), 56.8% (n\\u0026thinsp;=\\u0026thinsp;79) had tight contacts, while 43.2% (n\\u0026thinsp;=\\u0026thinsp;60) exhibited unacceptable proximal tightness (22.3% loose and 20.9% open). Disparities between facilities were significant; 75% of restorations at KNHDD had unacceptable contacts, compared to 26.7% at UoNDP and 30% at UoNDS. Multivariate analysis revealed that placement at KNHDD was strongly associated with both open (aRRR\\u0026thinsp;=\\u0026thinsp;4.71, p\\u0026thinsp;=\\u0026thinsp;0.008) and loose contacts (aRRR\\u0026thinsp;=\\u0026thinsp;33.88, p\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.001). Additionally, secondary caries showed a significant association with loose contacts (aRRR\\u0026thinsp;=\\u0026thinsp;6.08, p\\u0026thinsp;=\\u0026thinsp;0.02).\\u003c/p\\u003e\\u003ch2\\u003eConclusions\\u003c/h2\\u003e \\u003cp\\u003eThe study found a high prevalence (43.2%) of inadequate proximal contacts in Class II posterior RCRs in Nairobi, Kenya. This underscores a critical quality gap in restorative procedures, particularly in public hospital settings. There is an urgent need for enhanced educational initiatives and professional development to improve clinical techniques and ensure the long-term success of composite restorations in the region.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Evaluation of Proximal Contact Integrity and Associated Factors in Posterior Resin Composite Restorations: A Cross-sectional Study in Nairobi, Kenya\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2026-02-09 08:53:14\",\"doi\":\"10.21203/rs.3.rs-8547564/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0},{\"type\":\"decision\",\"content\":\"Revision requested\",\"date\":\"2026-03-19T14:48:10+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2026-02-22T21:39:28+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2026-02-19T10:04:28+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2026-02-18T23:27:41+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2026-02-18T03:42:27+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2026-02-17T12:33:28+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2026-02-14T15:33:16+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"192696686262180277947129240621715076624\",\"date\":\"2026-02-12T20:32:39+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"268424498576931113528899130685077289267\",\"date\":\"2026-02-12T13:35:47+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"227686909643586954845405930451543609934\",\"date\":\"2026-02-10T09:18:14+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"79063870685797101331341603355921530058\",\"date\":\"2026-02-09T12:10:16+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"168968889015487433297479793065450361847\",\"date\":\"2026-02-08T16:34:32+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"102310147854290827276060680435460697318\",\"date\":\"2026-02-06T23:08:14+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"142010985926510246314208706917800751522\",\"date\":\"2026-02-04T16:32:46+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewersInvited\",\"content\":\"\",\"date\":\"2026-02-04T11:21:22+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorInvited\",\"content\":\"\",\"date\":\"2026-01-12T06:26:45+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorAssigned\",\"content\":\"\",\"date\":\"2026-01-10T10:33:32+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"checksComplete\",\"content\":\"\",\"date\":\"2026-01-10T10:32:44+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"submitted\",\"content\":\"BMC Oral Health\",\"date\":\"2026-01-08T06:02:55+00:00\",\"index\":\"\",\"fulltext\":\"\"}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"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\":\"22e7e3ef-cbcd-4d0f-985d-ecda19520794\",\"owner\":[],\"postedDate\":\"February 9th, 2026\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"under-review\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2026-05-12T09:28:15+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2026-02-09 08:53:14\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-8547564\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-8547564\",\"identity\":\"rs-8547564\",\"version\":[\"v1\"]},\"buildId\":\"XKTyCvWXoU3ODBz1xrDgd\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}