Non-surgical root canal treatments in Public Dental Sector: characteristics of patients and teeth from 16-year register-based study

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As public dental services (PDS) play a crucial role in providing dental care, register-based studies offer valuable research-based data on magnitude of RCTs and characteristics of teeth and adults receiving such treatments. Objective The objective of this retrospective register-based study was to assess the magnitude of non-surgical root canal treatments (nsRCTs) carried out in PDS of the City of Helsinki between 2002–2017, and to describe characteristics of teeth and adults receiving nsRCT. Results A total number of 166 218 teeth were identified with root canal treatment code. Of these, 81,4% had completed nsRCT, and 18,6% were uncompleted. Younger adults and women received more frequently nsRCTs, compared to their older counterparts and men, respectively (p < 0.001). At tooth level, molars and teeth in upper jaw received more nsRCTs, compared to anterior teeth or premolars and teeth in lower jaw (p < 0.001). Most of the nsRCTs were started as planned treatment, compared to teeth with emergency opening, and were performed by general dentists (p < 0.001). Conclusion Our study offers wide picture of magnitude of nsRCTs carried out in Helsinki PDS. The nsRCTs carried out in public health sector differed by sex, age, tooth type and operator. These results could be used in improving cost-effective treatment planning and development of the strategies regarding treatment path at PDS. Root Canal Treatment Endodontics Retrospective Studies Dental Pulp Diseases Figures Figure 3 Figure 4 Figure 5 Introduction Finnish adults’ oral health has considerably improved over the past 30 years across the whole population, the most prominent change being the decrease in edentulousness [ 1 , 2 , 3 ]. Thus, adults retain throughout life their natural teeth, which at the time increases the need of dental care, including root canal treatment (RCT). According to National Public Health Institute, 25% of Finnish adults are estimated as having a need of RCT [ 4 ]. In nationwide survey, 61% of Finnish dentate adults aged 30 years or older had radiographically at least one root canal treated tooth (RCTT), with predominance among older adults and women [ 5 ]. This is slightly higher than that reported (51% to 59%) for Danish [ 6 ] and (23% to 53%) for Norwegian [ 7 ] adults, but lower than that for Swedes (85%) [ 8 ]. Worldwide, 56% of adults have at least one RCTT [ 9 ]. Finnish Public Dental Service (PDS) gave access to its subsidized services to younger age groups of adults since 1980s, and all remaining age restrictions on access were removed in 2002 [ 10 ]. Annual attendance of Finnish adults in PDS was 31.9% in a three-year period between 2006–2008 [ 11 ]. In the city of Helsinki, a recent publication showed that the overall annual attendance of adults over 20-years-old in public and private dental care together was between 48.8–51.9% in the period of 2007 to 2017 [ 12 ]. In Finland, of all treatment measures provided in PDS, endodontic treatments including other than primary nsRCTs were 3.8% in 2009 [ 10 ] and 5.3% in 2001–2013 [ 13 ]. Other register-based studies have also been published from Scandinavia with results on characteristics of individuals and teeth receiving RCT as well as outcomes of RCT [ 14 , 15 , 16 , 17 ]. In Sweden, a register-based study found that average age of individuals at the time of root filling was 55 years (range 20–102) and maxillary teeth and mandibular first molar were the most frequently root-filled tooth. However, no significant differences between genders were discovered [ 17 ]. Similar findings are also found in other Swedish study from public dental clinics where molars had most often RCT but the mean age was lower 48.3 (SD = 16.4) [ 18 ]. RCT is mainly indicated when the pulp is irreversibly damaged, inflamed or necrotic with or without clinical and/or radiological findings of apical periodontitis (AP) [ 19 ]. Other indications could be failure of a primary RCT, an elective devitalization, e.g. to provide post space, doubtful pulp health prior to restorative procedures, likelihood of pulpal exposure when restoring a misaligned tooth and prior to root resection or apicoectomy. In general dental practise, RCT is most often initiated due to caries and for vital molar teeth [ 20 ] or AP [ 18 ]. RCTs are performed mainly by general dentists (GD) or specialized dentists in endodontics. Differences exist between operators when comparing treatment decisions [ 21 ] or quality of RCT and number of visits [ 22 ]. Further, RCTs are considered difficult and stressful by GDs, particularly treatments on molars [ 23 ]. This is one reason why referrals of GDs to endodontists are more common in molar teeth [ 24 ], and why molars are usually more often treated by endodontists [ 25 ]. However, the knowledge of dentists in nsRCT vary tremendously [ 26 ]. This study focuses on describing the backgrounds of individuals who have had a nsRCT in Helsinki PDS and distribution of nsRCT on tooth types and differences between operators. These insights help to identify which patient groups and tooth types are most affected, contributing to improved prevention, treatment planning and policy development. Objective The aim of this study was to assess the magnitude of non-surgical RCTs (nsRCTs) carried out among adult patients in Helsinki PDS based on 16-year observation time between 2002 and 2017. Further, the study aimed to investigate frequencies of nsRCTs by patient, tooth- and operator-related factors as described in more detail further. Material and methods Data was collected from an electronic health record systems EFFICA and Lifecare (Tieto Oyj, Helsinki, Finland) used by Helsinki PDS. Finland offers dental care for free of charge for patients under 18-years-old while adults pay their dental service by subsidized-fees. Endodontic treatments in Helsinki PDS are provided by general dentists (GD), endodontists, dental students and by GDs in so-called purchased service, where the city is paying for the private clinics to offer dental services for citizens. The time period of interest in this study was from 2002 to 2017. The inclusion criteria for this study were adult patients of the age of at least 18 years with nsRCT procedure code in their dental history of any permanent teeth. Procedures on third molars or primary teeth were excluded. For type of tooth, teeth were numbered according to the ISO 3950 system, where the teeth are charted with the quadrant number (1— maxillary right, 2— maxillary left, 3— mandibular left, 4— mandibular right, followed by the tooth number, which starts from the midlines of each jaw from 1 to 7. Patient-related characteristics were patient age and gender, and tooth-related characteristics were tooth type and jaw location. The age of the patients was grouped into 5 categories: 18–29, 30–49, 50–64, 65–74, 75 + years. Root canal procedure-related information was the nature of dental visit of root canal opening and how many times tooth has had completed root canal filling. Operator-related factors were defined as operator who carried out the nsRCT (endodontists, GDs in both public or purchased service, or dental student). Operator-related information was available from the years 2002–2016. Flowchart in Fig. 1 shows included individuals and teeth as well as the number of times teeth have had nsRCT. Figure 1 . Flowchart of study adults. Uncompleted nsRCTs and number of times teeth have undergone completed nsRCT in Helsinki PDS between 2002–2017. Ethical considerations Data was acquired from encrypted summary from digital health records. No individuals were identified, and ethical permission was not necessary. Permission for this study was granted by the City of Helsinki (Research permission HEL2022-013077). Statistical analyses Further processing of the data was done with IBM SPSS Statistics, version 28 (IBM Corp., Armonk, N.Y., USA). We used Chi-square test for categorical variables to evaluate differences between groups. Bonferroni correlation was used in post-hoc chi-square test. Categorical variables are presented with percentages. Pearson correlation test was used to test significance of trend line. Results Study population According to patient records, 88 735 adults were identified as having at least one completed non-surgical root canal treatment in Helsinki PDS during the 16 years of observation period of the present study. A total number of 166 208 teeth with endodontic treatment codes were found. Of them, 18.6% (n = 30 921) were uncompleted nsRCTs, 78.7% (n = 130 835) were filled once, and the rest underwent root canal filling twice (2.6%) or more (0.08%). For the final analysis, only teeth with at least one completed nsRCT were included. Women represented 52.8% of the study population, and men counted for 47.2% of the cases. All tooth types were included with molars being most frequently root canal treated (49.4%). Mean age of the adults at the time of root filling was 43.2 (SD 15.1). NsRCTs by operators The yearly amount of completed nsRCTs ranged from 6 140 (in 2002) to 10 108 (in 2010). Most of the nsRCTs were performed by GDs; until 2006 by those engaged in PDS and after that by those in purchased service. Of all nsRCTs in 2002–2016, 32.9% (n = 42 155) were carried out by GDs in PDS, 60.0% (n = 76 939) by GDs in purchased service. Of all, 3.3% (n = 4 245) were carried out by endodontists and 3.8% by dental students (n = 4 844). Trend line analysis shows that yearly amount of completed nsRCT did not differ by years (p = 0.867). Figure 2 shows teeth with nsRCTs by year of observation and by operators. Figure 2 . Teeth with completed first non-surgical root canal treatments (n = 135 287) among 88 735 adults in Helsinki Public Dental Service, by years of observation (2002–2017) and by operator (2002–2016). GD = general dentist, SD = specialist dentist in endodontics, PS = dentist engaged with purchased service, DS = dental student. NsRCTs by patient-related factors Of all nsRCTs, 89.6% were performed in younger than 65-year-olds. No statistically significant differences were found by patient gender. There was a statistically significant difference between age groups in gender, tooth type, the nature of root canal opening, and operator. Table 1 shows completed first nsRCTs by patient- and tooth-level factors. Table 1 Table 1 Backgrounds of adults (n = 88 735) identified as having at least one fully completed nsRCTs and characteristics of their teeth received such treatments during present study period 2002–2017 and by operator’s position during 2002–2016 in Helsinki PDS. Each subscript letter indicates a subset of age categories within one variable whose columns properties do not differ significantly from other groups with Bonferroni correlation. Percentages indicate the proportion in each age category. Age (years) 18–29 30–49 50–64 65–74 75– All %, row P-value n (%) n (%) n (%) n (%) n (%) Patient level: Sex Women Men 11186 a (53.8%) 9623 (46.2%) 20598 b (50.9%) 19833 (49.1%) 9817 a (54.0%) 8351 (46.0%) 3510 a (55.6%) 2806 (44.4%) 1698 a (56.4%) 1313 (43.6%) 46809 41926 52.8% 47.2% < 0.001 All 20809 (23.5%) 40431 (45.6%) 18168 (20.5%) 6316 (7.1%) 3011 (3.4%) 88735 100% Tooth-level : Tooth type Anterior teeth Premolars Molars 3683 a (12.6%) 8587 a (29.4%) 16912 a (58.0%) 7943 a (12.6%) 20247 b (32.2%) 34658 b (55.1%) 7153 b (24.5%) 10169 c (34.8%) 11886 c (40.7%) 3503 c (36.6%) 3456 c (36.1%) 2624 d (27.4%) 2313 d (51.8%) 1395 a,b (31.2%) 758 e (17.0%) 24595 43854 66838 18.2% 32.4% 49.4% < 0.001 Tooth location Maxilla Mandible 16696 a (57.2%) 12486 (42.8%) 35589 a,b (56.6%) 27259 (43.4%) 16269 b (55.7%) 12939 (44.3%) 5358 a,b (55.9%) 4225 (44.1%) 2296 c (51.4%) 2170 (48.6%) 76208 59079 56.3% 43.7% < 0.001 Nature of RC opening Planned Emergency 26375 a (89.4%) 3133 (10.6%) 56772 b (90.4%) 5998 (9.6%) 26534 c (91.4%) 2511 (8.6%) 8856 d (92.7%) 694 (7.3%) 4090 d (92.7%) 324 (7.2%) 122627 12660 90.6% 9.4% < 0.001 Operator General dentist Endodontist General dentist in purchased service Dental student 9071 a (32.8%) 825 a (3.0%) 17068 a (61.7%) 693 a (2.5%) 19835 a (33.1%) 1787 a (3.0%) 36556 a (61.0%) 1743 b (2.9%) 8234 b (30.0%) 1020 b (3.7%) 16711 a (60.8%) 1523 c (5.5%) 2782 b (31.1%) 436 c (4.9%) 5062 b (56.5%) 673 d (7.5%) 2233 c (53.6%) 177 b,c (4.3%) 1542 c (37.0%) 212 c (5.1%) 42155 4245 76939 4844 32.9% 3.3% 60.0% 3.8% < 0.001 All 29182 (46,2%) 62848 (46.5%) 29208 (21.6%) 9583 (7.1%) 4466 (3.3%) 135287 100% *Not included in other numbers Frequency of nsRCT in different tooth types NsRCTs were mostly performed to molars and premolars. In maxilla, first and second molars were the most common individual teeth to have nsRCT. First upper molars counted for 24.8% of all the upper teeth, followed by second premolars (22.7%) and second molars (13.5%). Anterior teeth had less often nsRCT compared to posterior teeth. In mandible, first and second molars were together the most susceptible for nsRCT. First lower molars had 41.2% of nsRCTs of all the lower teeth. In addition, lower second molars and second premolars were frequently subject to nsRCT. Lower anterior teeth had less nsRCTs than the lower posterior teeth. In this dataset, tooth 46 had the most nsRCTs of the whole dentition representing 9.2% of all the cases. Figure 3 visualize the distribution of nsRCTs in upper and lower teeth. Comparing nsRCT by tooth type and operator, we found that molars were more often treated than anterior teeth by both endodontists and group of GDs, dentists in purchased service and dental students (p < 0.001). but mostly by GDs in purchased service (64,7% of all molar teeth). In percentages, endodontists compared to other operators performed similar proportion of nsRCTs on molar teeth (Table 2 ). Figure 3 . Adults’ upper and lower teeth with identified as having at least one completed nsRCT (first or further treatment) during our study period 2002–2017 in Helsinki PDS. Table 2 Table 2 NsRCT on different tooth types by operators between 2002 and 2016. Chi-square test was used. Each subscript letter indicates a subset of tooth categories within operator which do not differ significantly from other groups with Bonferroni correlation. Percentages indicate the proportion of treated teeth in each age category by operator. Operaror Anterior Premolars Molars All P-value n (%) n (%) n (%) Endodontist 1296 a (30.5%) 1106 b (26.1%) 1843 b (43.4%) 4245 Others 21845 a (17.6%) 40388 b (32.6%) 61705 b (49.8%) 123938 All 23141 41494 63548 128183 < 0.001 Discussion Based on our data, the volume of nsRCTs increased slighly in Helsinki PDS between 2002–2017. Annual number of nsRCTs ranged from the lowest (n = 6 140) in 2002 to the highest (n = 10 108) in 2010. At total, 135 287 teeth were assessed statistically in this study. In 2007, a sudden drop in the amount of performed nsRCTs might be related to beginning of the purchased service. And if year 2003 would have been the starting point in our data, there would have been almost no change in the trend line. Though, before a law reform in 2002, dental care in PDS was age restricted, leading to a situation where only special-need groups of adults had access to public dental care [ 27 ]. It is important to note that the positive trend line was not statistically significant. Interestingly, 30 921 (22,9%) teeth were found to have only dental code for root canal opening, but without obturation. Part of this could be explained by the fact that patients have had root canal filling in private sector rather than in Helsinki PDS even thought it is not unusual that RCTs are not completed [ 28 ]. In the study by Linden et al. 2020 [ 13 ] where data was gathered from five PDS in Southern Finland in the period of 2001–2013, endodontic treatments had statistically highly significant increasing trend among 18-39-year-olds. However, the volume of endodontic treatments was found to have a descending trend in both public and private dental care over an 11-year period in the city of Helsinki, overlapping partly with our period of investigation [ 12 ]. Though, endodontic treatments included other procedures than primary nsRCTs in both studies. And their data was aggregated into 5-year patient age groups, possibly hiding sociodemographic changes in the population. Also, number of RCTT has been found to be decreasing in private sector, from 83 241 in 2012 to 61 188 in 2017 [ 29 ]. In turn, prevalence of RCTT for Danish adults with baseline age of 20 or older in three consecutive examinations were 51%, 57% and 59% in years 1997, 2003 and 2008, respectively [ 6 ]. It is the expected finding since it was assessed from the same cohort followed in three consecutive years. Other similar cohort from Denmark shows coterminous results with prevalence of RCTT within adults aged 20–64 years being 44.1% (2009), 45.9% (2014), 51.8% (2018) [ 30 ]. For instance, in Oslo repeated cross-sectional study of 35-year-olds with an approximately 10-year interval showed the prevalence of root filled teeth as 50%, 53%, 24% and 23% in years 1973, 1984, 1993 and 2003 with decreasing trend [ 31 ]. The same decreasing trend was seen in Sweden between 1973 and 2013 in all age groups from 3 to 80 years [ 32 ]. Even though our data shows a slightly positive trend in annual nsRCTs, further conclusions are hard to draw. The prevalence of RCTT and the amount of annual RCT vary slightly in each study. Could this be due to differences in study methods or are there possibly less teeth extractions leading to growth of RCTT? In large nationwide observational study from Finland, the mean number of extractions per patient was 0.17 in 2012 and 0.18 in 2017 in private sector, not supporting the hypothesis of less extractions [ 33 ]. However, other study found that in Helsinki PDS, rate of extractions grew in function of age and rate of endodontic treatments decreased even though the trend in extractions didn’t change over time [ 34 ]. Also, differences in healthcare systems complicate the comparison between studies. It is important to clarify that many studies discuss endodontic treatments in general, including retreatments and surgical procedures. As our study focuses on primary nsRCTs, this limits the comparative value to other studies. In our data, the age group of 30–49 had the most nsRCTs (45.6% of all nsRCTs, n = 40 431). Age was significantly associated with gender, tooth type, the nature of root canal opening, and operators. We found no statistical differences between sex. In private Finnish dental clinics, the weighted mean age of an endodontic patient was 53.6 years in 2012 and 55.9 years in 2017 [ 29 ]. In our data, mean age at the time of root canal filling was 43.2 (SD 15.1). This is lower than for Fransson et al. 2016 (mean age 55, range 20–102) which studied individuals from both public and private sector [ 17 ] or for Wigsten et al. 2019 (mean age 48.3, SD 16.4) [ 18 ] but similar to other study conducted at PDS in Finland [ 35 ]. Additionally, in our data the number of patients decreased constantly in every age category without any peaks in the oldest groups found in other studies [ 17 , 36 , 37 ]. For example, the mean age of patients with AP varies globally between 26–52 years [ 38 ]. Apical periodontitis is a slowly developing condition and can remain symptomless for long periods [ 39 ], and for the oldest quartile of the population, extraction could be more often favored over endodontic treatment which could partly explain our results. Our findings of nsRCTs performed in the Helsinki PDS, give also a good overall picture of the distribution of nsRCTs in a Finnish public dental care system. Most of the nsRCTs are performed by GDs, followed by GDs in the purchased service whose role in the public service has grown in the last 15 years. Endodontists’ and dental students' proportion of all nsRCTs has been nearly unchanged, being 3.1% and 3.8% respectively. Due to changes in the patient record system in 2017, we don’t have data of the distribution of performed nsRCTs in that year. A great majority of the performed nsRCTs were planned in every age category. The proportion of emergency root canal openings were around 10% of all the openings for most of the age categories. When interpreting the statistics from emergency or planned nsRCT, it is crucial to keep in mind that the use of dental codes may vary between dentists. Part of adults with assessed need for nsRCT started as emergency care are referred to purchased service of the City, for planned treatments to be completed by general dentists. This practice of combining public and purchased service is due to disequilibrium of demand of oral health treatment and supplier capacity at PDS since the adult population has been given access to care without age restrictions. As we don’t know the exact reasons for emergency treatment, we suppose that they are related to trauma or acute pain due to inflammation of the pulp or periradicular conditions [ 40 ]. It is important to note that the use of dental codes is not consistent within dentists, and other codes than those we used for calculations, could have been used. We found that both in maxilla and in mandible, posterior teeth have had more often nsRCT than the anterior teeth which is in line with few other studies [ 28 , 41 ], but different from a study conducted in private sector in Finland [ 29 ]. First upper and lower molars were the most treated teeth. First lower molars were found to be the most prevalent ones in terms of nsRCT as in previous studies [ 17 , 42 ]. Cross-sectional study of over 20 000 teeth found that AP was most prevalent in the first upper molars in maxilla and in the first lower molars in mandible. Except for maxillary anterior teeth, the same study found also that the prevalence of AP was lower in anterior teeth of mandible [ 43 ]. While AP is one of the main reasons for nsRCT, this might explain our findings. Molars might be more affected by caries and thus by pulpitis and AP, when anterior teeth are more susceptible to nsRCT due to trauma [ 36 ]. Molars' difficult position for brushing and more complex morphology might favor bacteria to cause decay in comparison to anterior teeth. Additionally, molars along with anterior teeth are the first ones to erupt which could be the reason they receive most of the treatments. In our study, upper anterior teeth had more nsRCTs than lower anterior teeth. These results are similar to few other studies [ 44 , 45 ]. One of the reasons could be that they are the first teeth to get hit in a potential trauma. Additionally, we compared whether tooth groups differed by operators. We found that endodontists and other operators performed nsRCTs more on molars rather than anterior teeth which inverse to private sector in Finland [ 29 ]. Interestingly, group of GDs and dental student performed nsRCTs on molar teeth in almost half of the cases (49.8%). This is rather surprising as in some other countries GDs do not perform nsRCTs on molars as often as endodontists [ 25 ]. The strength of the present study is that data comes from a large practice-based database of Helsinki PDS. As public services are important part of Finland’s dental care, this study provides good insights of nsRCTs among adult population. The study design provides a reliable view of current clinical practice for almost two decades. As register-based study design at the same time is a weakness of this study because all results are based on registers recorded by dental operators in electronic patient record system. Thus, any missing or not recorded information is handled as it is. The observed association between age groups and spesific tooth types treated underscore the need for age-sensitive approaches in treatment planning and preventive care. The use of comprehensive register-based data demonstrates the value of longitudinal public health records and guiding evidence-based decision-making. However, limitations such as missing clinical details or socioeconomic variables suggest that future studies should aim to integrate richer datasets to provide a more holistic view of patient and treatment profiles. Conclusion An important number of nsRCTs are carried out by mainly general dentists in Helsinki PDS. The yearly amount of nsRCTs remained mainly unchanged during 16 years of observation time even with improved oral health of population. Significant differenced of amount of nsRCTs exists by adult’s age group and sex, as well as their tooth type and location. Special attention should be paid in amount of uncompleted nsRCTs. To our knowledge, this is the first study conducted in Nordic countries focusing solely on frequencies of nsRCTs, and patient-related factors (age, sex, tooth type, jaw) and operators at PDS for 16 years. Studying further on nsRCT based on clinical outcomes would be future area of interest. Declarations Conflict of interest We have no conflict of interest to disclose. Funding We have not received any funding for this article. Author Contribution Milo Väisänen (MV), [ [email protected] ](mailto: [email protected] ) : Writing, Editing, Data HandlingJussi Furuholm (JF), [ [email protected] ](mailto: [email protected] ) : Conceptualization, Methodology, Writing, Data handlingUlla Palotie (UP), [ [email protected] ](mailto: [email protected] ) : Reviewing, EditingTseveenjav Battsetseg (TB), [ [email protected] ](mailto: [email protected] ) : Reviewing, Editing, Conceptualization, Supervision References Suominen–Taipale L, Nordblad A, Vehkalahti M, Aromaa A (eds) (2004) Suomalaisten aikuisten suunterveys: Terveys 2000 –tutkimus. Helsinki: Kansanterveyslaitos; (KTL B16/2004). Available from: https://www.julkari.fi/bitstream/handle/10024/78322/2004b16.pdf Suominen-Taipale L, Vehkalahti (2011) Knuuttila. Terveys, toimintakyky ja hyvinvointi Suomessa Helsinki: Terveyden ja hyvinvoinnin laitos; 2012. 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Int Endod J 52(2):158–168. 10.1111/iej.12998 Duncan HF, Kirkevang LL, Peters OA, El-Karim I, Krastl G, Del Fabbro M, Chong BS, Galler KM, Segura-Egea JJ, Kebschull M (2023) ESE Workshop Participants and Methodological Consultant. Treatment of pulpal and apical disease: The European Society of Endodontology (ESE) S3- level clinical practice guideline. Int Endod J 56(Suppl 3):238–295. 10.1111/iej.13974 Bjørndal L, Laustsen MH, Reit C (2006) Root canal treatment in Denmark is most often carried out in carious vital molar teeth and retreatments are rare. Int Endod J 39(10):785–790. 10.1111/j.1365-2591.2006.01149.x Çiçek E, Özsezer-Demiryürek E, Özerol-Keskin NB, Murat N (2016) Comparison of treatment choices among endodontists, postgraduate students, undergraduate students and general dentists for endodontically treated teeth. Int Dent J 66(4):201–207. 10.1111/idj.12222 Pietrzycka K, Radwanski M, Hardan L, Bourgi R, Mancino D, Haikel Y, Lukomska-Szymanska M (2022) The Assessment of Quality of the Root Canal Filling and the Number of Visits Needed for Completing Primary Root Canal Treatment by Operators with Different Experience. Bioeng (Basel) 9(9):468. 10.3390/bioengineering9090468 Dahlström L, Lindwall O, Rystedt H, Reit C (2017) Working in the dark': Swedish general dental practitioners on the complexity of root canal treatment. Int Endod J 50(7):636–645. 10.1111/iej.12675 Wolcott JF, Terlap HT (2014) Follow-up survey of general dentists to identify characteristics associated with increased referrals to endodontists. J Endod 40(2):204–210. 10.1016/j.joen.2013.10.033 Mungia R, Funkhouser E, Law AS, Nixdorf DR, Rubin RL, Gordan VV, Fellows JL, Gilbert GH, National Dental PBRN Collaborative Group (2025) Characteristics of teeth and patients receiving root canal treatment in National Dental PBRN practices: Comparison between Endodontist and general dentist practices. J Dent 157:105723. 10.1016/j.jdent.2025.105723 Monsef E, Goodman X, Patil R, White SN (2024) Dentists' knowledge of non-surgical root canal treatment, a systematic review. J Dent 145:104975. 10.1016/j.jdent.2024.104975 Niiranen T, Widström E, Niskanen T (2008) Oral Health Care Reform in Finland - aiming to reduce inequity in care provision. BMC Oral Health 8:3. 10.1186/1472-6831-8-3 Wigsten E, EndoReCo; Kvist T (2022) Patient record assessment of results and related resources spent during 1 year after initiation of root canal treatment in a Swedish public dental organization. Int Endod J 55(5):453–466. 10.1111/iej.13699 Vehkalahti MM, Palotie U, Valaste M (2020) Age-specific findings on endodontic treatments performed by private dentists in Finland in 2012 and 2017: a nationwide register-based observation. Int Endod J 53(6):754–763. 10.1111/iej.13284 Razdan A, Schropp L, Væth M, Kirkevang LL (2024) Longitudinal study of endodontic and periapical status of an adult Danish population examined in 2009, 2014, and 2019: a repeated cohort study. Acta Odontol Scand 83:20–29. 10.1080/00016357.2023.2268699 Skudutyte-Rysstad R, Eriksen HM (2006) Endodontic status amongst 35-year-old Oslo citizens and changes over a 30-year period. Int Endod J 39(8):637–642. 10.1111/j.1365-2591.2006.01129.x Norderyd O, Koch G, Papias A, Köhler AA, Helkimo AN, Brahm CO, Lindmark U, Lindfors N, Mattsson A, Rolander B, Ullbro C, Gerdin EW, Frisk F (2015) Oral health of individuals aged 3–80 years in Jönköping, Sweden during 40 years (1973–2013). II. Review of clinical and radiographic findings. Swed Dent J 39(2):69–86 PMID: 26529833 Vehkalahti MM, Ventä I, Valaste M (2023) Frequency and type of tooth extractions in adults vary by age: register-based nationwide observations in 2012–2017. Acta Odontol Scand 81(4):259–266. 10.1080/00016357.2022.2130977 Hiltunen K, Mäntylä P, Vehkalahti MM (2021) Age- and Time-Related Trends in Oral Health Care for Patients Aged 60 Years and Older in 2007–2017 in Public Oral Health Services in Helsinki, Finland. Int Dent J 71(4):321–327. 10.1016/j.identj.2020.12.006 Laajala A, Nuutinen M, Luttinen A, Vähänikkilä H, Tanner T, Laitala ML, Karki S (2024) Survival of endodontically treated teeth in public dental service in Northern Finland: a practise-based register study. Acta Odontol Scand 83:190–196. 10.2340/aos.v83.40491 Van Nieuwenhuysen JP, D'Hoore W, Leprince JG (2023) What ultimately matters in root canal treatment success and tooth preservation: A 25-year cohort study. Int Endod J 56(5):544–557. 10.1111/iej.13895 Lerdchakorn S, Porntaveetus T, Panitvisai P, Kulvitit S (2024) Etiologies of non-surgical root canal treatment and its association with risk factors in a selected Thai population. BMC Oral Health 24(1):985. 10.1186/s12903-024-04762-0 Jakovljevic A, Nikolic N, Jacimovic J, Pavlovic O, Milicic B, Beljic-Ivanovic K, Miletic M, Andric M, Milasin J (2020) Prevalence of Apical Periodontitis and Conventional Nonsurgical Root Canal Treatment in General Adult Population: An Updated Systematic Review and Meta-analysis of Cross-sectional Studies Published between 2012 and 2020. J Endod 46(10):1371–1386e8. 10.1016/j.joen.2020.07.007 Ørstavik D,Essential endodontology: prevention and treatment of apical periodontitis / edited by, Orstavik D (eds) (2020) Third edition; pp 267–292. Hoboken, New Jersey: Wiley Blackwell Abbott PV (2022) Present status and future directions: Managing endodontic emergencies. Int Endod J 55:778–803. 10.1111/iej.13678 Helminen SE, Vehkalahti M, Kerosuo E, Murtomaa H (2000) Quality evaluation of process of root canal treatments performed on young adults in Finnish public oral health service. J Dent 28(4):227–232. 10.1016/s0300-5712(99)00076-7 Serene TP, Spolsky VW (1981) Frequency of endodontic therapy in a dental school setting. J Endod 7(8):385–387. 10.1016/S0099-2399(81)80062-3 Meirinhos J, Martins JNR, Pereira B, Baruwa A, Gouveia J, Quaresma SA, Monroe A, Ginjeira A (2020) Prevalence of apical periodontitis and its association with previous root canal treatment, root canal filling length and type of coronal restoration - a cross-sectional study. Int Endod J 53(4):573–584. 10.1111/iej.13256 Scavo R, Martinez Lalis R, Zmener O, Dipietro S, Grana D, Pameijer CH (2011) Frequency and distribution of teeth requiring endodontic therapy in an Argentine population attending a specialty clinic in endodontics. Int Dent J 61(5):257–260. 10.1111/j.1875-595X.2011.00069.x Al-Negrish AR (2002) Incidence and distribution of root canal treatment in the dentition among a Jordanian sub population. Int Dent J 52(3):125–129. 10.1111/j.1875-595x.2002.tb00616.x Additional Declarations No competing interests reported. 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Thus, adults retain throughout life their natural teeth, which at the time increases the need of dental care, including root canal treatment (RCT). According to National Public Health Institute, 25% of Finnish adults are estimated as having a need of RCT [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. In nationwide survey, 61% of Finnish dentate adults aged 30 years or older had radiographically at least one root canal treated tooth (RCTT), with predominance among older adults and women [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. This is slightly higher than that reported (51% to 59%) for Danish [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] and (23% to 53%) for Norwegian [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] adults, but lower than that for Swedes (85%) [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Worldwide, 56% of adults have at least one RCTT [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFinnish Public Dental Service (PDS) gave access to its subsidized services to younger age groups of adults since 1980s, and all remaining age restrictions on access were removed in 2002 [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Annual attendance of Finnish adults in PDS was 31.9% in a three-year period between 2006\u0026ndash;2008 [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. In the city of Helsinki, a recent publication showed that the overall annual attendance of adults over 20-years-old in public and private dental care together was between 48.8\u0026ndash;51.9% in the period of 2007 to 2017 [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In Finland, of all treatment measures provided in PDS, endodontic treatments including other than primary nsRCTs were 3.8% in 2009 [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] and 5.3% in 2001\u0026ndash;2013 [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Other register-based studies have also been published from Scandinavia with results on characteristics of individuals and teeth receiving RCT as well as outcomes of RCT [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. In Sweden, a register-based study found that average age of individuals at the time of root filling was 55 years (range 20\u0026ndash;102) and maxillary teeth and mandibular first molar were the most frequently root-filled tooth. However, no significant differences between genders were discovered [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Similar findings are also found in other Swedish study from public dental clinics where molars had most often RCT but the mean age was lower 48.3 (SD\u0026thinsp;=\u0026thinsp;16.4) [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eRCT is mainly indicated when the pulp is irreversibly damaged, inflamed or necrotic with or without clinical and/or radiological findings of apical periodontitis (AP) [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Other indications could be failure of a primary RCT, an elective devitalization, e.g. to provide post space, doubtful pulp health prior to restorative procedures, likelihood of pulpal exposure when restoring a misaligned tooth and prior to root resection or apicoectomy. In general dental practise, RCT is most often initiated due to caries and for vital molar teeth [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] or AP [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. RCTs are performed mainly by general dentists (GD) or specialized dentists in endodontics. Differences exist between operators when comparing treatment decisions [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] or quality of RCT and number of visits [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Further, RCTs are considered difficult and stressful by GDs, particularly treatments on molars [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. This is one reason why referrals of GDs to endodontists are more common in molar teeth [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], and why molars are usually more often treated by endodontists [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. However, the knowledge of dentists in nsRCT vary tremendously [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThis study focuses on describing the backgrounds of individuals who have had a nsRCT in Helsinki PDS and distribution of nsRCT on tooth types and differences between operators. These insights help to identify which patient groups and tooth types are most affected, contributing to improved prevention, treatment planning and policy development.\u003c/p\u003e"},{"header":"Objective","content":"\u003cp\u003eThe aim of this study was to assess the magnitude of non-surgical RCTs (nsRCTs) carried out among adult patients in Helsinki PDS based on 16-year observation time between 2002 and 2017. Further, the study aimed to investigate frequencies of nsRCTs by patient, tooth- and operator-related factors as described in more detail further.\u003c/p\u003e"},{"header":"Material and methods","content":"\u003cp\u003eData was collected from an electronic health record systems EFFICA and Lifecare (Tieto Oyj, Helsinki, Finland) used by Helsinki PDS. Finland offers dental care for free of charge for patients under 18-years-old while adults pay their dental service by subsidized-fees. Endodontic treatments in Helsinki PDS are provided by general dentists (GD), endodontists, dental students and by GDs in so-called purchased service, where the city is paying for the private clinics to offer dental services for citizens.\u003c/p\u003e\u003cp\u003eThe time period of interest in this study was from 2002 to 2017. The inclusion criteria for this study were adult patients of the age of at least 18 years with nsRCT procedure code in their dental history of any permanent teeth. Procedures on third molars or primary teeth were excluded. For type of tooth, teeth were numbered according to the ISO 3950 system, where the teeth are charted with the quadrant number (1\u0026mdash; maxillary right, 2\u0026mdash; maxillary left, 3\u0026mdash; mandibular left, 4\u0026mdash; mandibular right, followed by the tooth number, which starts from the midlines of each jaw from 1 to 7.\u003c/p\u003e\u003cp\u003ePatient-related characteristics were patient age and gender, and tooth-related characteristics were tooth type and jaw location. The age of the patients was grouped into 5 categories: 18\u0026ndash;29, 30\u0026ndash;49, 50\u0026ndash;64, 65\u0026ndash;74, 75\u0026thinsp;+\u0026thinsp;years. Root canal procedure-related information was the nature of dental visit of root canal opening and how many times tooth has had completed root canal filling. Operator-related factors were defined as operator who carried out the nsRCT (endodontists, GDs in both public or purchased service, or dental student). Operator-related information was available from the years 2002\u0026ndash;2016. Flowchart in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows included individuals and teeth as well as the number of times teeth have had nsRCT.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Flowchart of study adults. Uncompleted nsRCTs and number of times teeth have undergone completed nsRCT in Helsinki PDS between 2002\u0026ndash;2017.\u003c/p\u003e\n\u003ch3\u003eEthical considerations\u003c/h3\u003e\n\u003cp\u003eData was acquired from encrypted summary from digital health records. No individuals were identified, and ethical permission was not necessary. Permission for this study was granted by the City of Helsinki (Research permission HEL2022-013077).\u003c/p\u003e\n\u003ch3\u003eStatistical analyses\u003c/h3\u003e\n\u003cp\u003eFurther processing of the data was done with IBM SPSS Statistics, version 28 (IBM Corp., Armonk, N.Y., USA). We used Chi-square test for categorical variables to evaluate differences between groups. Bonferroni correlation was used in post-hoc chi-square test. Categorical variables are presented with percentages. Pearson correlation test was used to test significance of trend line.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003eStudy population\u003c/h2\u003e\u003cp\u003e According to patient records, 88 735 adults were identified as having at least one completed non-surgical root canal treatment in Helsinki PDS during the 16 years of observation period of the present study. A total number of 166 208 teeth with endodontic treatment codes were found. Of them, 18.6% (n\u0026thinsp;=\u0026thinsp;30 921) were uncompleted nsRCTs, 78.7% (n\u0026thinsp;=\u0026thinsp;130 835) were filled once, and the rest underwent root canal filling twice (2.6%) or more (0.08%). For the final analysis, only teeth with at least one completed nsRCT were included. Women represented 52.8% of the study population, and men counted for 47.2% of the cases. All tooth types were included with molars being most frequently root canal treated (49.4%). Mean age of the adults at the time of root filling was 43.2 (SD 15.1).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eNsRCTs by operators\u003c/h2\u003e\u003cp\u003eThe yearly amount of completed nsRCTs ranged from 6 140 (in 2002) to 10 108 (in 2010). Most of the nsRCTs were performed by GDs; until 2006 by those engaged in PDS and after that by those in purchased service. Of all nsRCTs in 2002\u0026ndash;2016, 32.9% (n\u0026thinsp;=\u0026thinsp;42 155) were carried out by GDs in PDS, 60.0% (n\u0026thinsp;=\u0026thinsp;76 939) by GDs in purchased service. Of all, 3.3% (n\u0026thinsp;=\u0026thinsp;4 245) were carried out by endodontists and 3.8% by dental students (n\u0026thinsp;=\u0026thinsp;4 844). Trend line analysis shows that yearly amount of completed nsRCT did not differ by years (p\u0026thinsp;=\u0026thinsp;0.867). Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows teeth with nsRCTs by year of observation and by operators.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Teeth with completed first non-surgical root canal treatments (n\u0026thinsp;=\u0026thinsp;135 287) among 88 735 adults in Helsinki Public Dental Service, by years of observation (2002\u0026ndash;2017) and by operator (2002\u0026ndash;2016). GD\u0026thinsp;=\u0026thinsp;general dentist, SD\u0026thinsp;=\u0026thinsp;specialist dentist in endodontics, PS\u0026thinsp;=\u0026thinsp;dentist engaged with purchased service, DS\u0026thinsp;=\u0026thinsp;dental student.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eNsRCTs by patient-related factors\u003c/h3\u003e\n\u003cp\u003eOf all nsRCTs, 89.6% were performed in younger than 65-year-olds. No statistically significant differences were found by patient gender. There was a statistically significant difference between age groups in gender, tooth type, the nature of root canal opening, and operator. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows completed first nsRCTs by patient- and tooth-level factors.\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\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\u003eBackgrounds of adults (n\u0026thinsp;=\u0026thinsp;88 735) identified as having at least one fully completed nsRCTs and characteristics of their teeth received such treatments during present study period 2002\u0026ndash;2017 and by operator\u0026rsquo;s position during 2002\u0026ndash;2016 in Helsinki PDS. Each subscript letter indicates a subset of age categories within one variable whose columns properties do not differ significantly from other groups with Bonferroni correlation. Percentages indicate the proportion in each age category.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\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\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (years)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18\u0026ndash;29\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e30\u0026ndash;49\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e50\u0026ndash;64\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e65\u0026ndash;74\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e75\u0026ndash;\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eAll\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e%, row\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003en (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003en (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003en (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003en (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003en (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePatient level:\u003c/p\u003e\u003cp\u003eSex\u003c/p\u003e\u003cp\u003eWomen\u003c/p\u003e\u003cp\u003eMen\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11186\u003csup\u003ea\u003c/sup\u003e (53.8%)\u003c/p\u003e\u003cp\u003e9623 (46.2%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20598\u003csup\u003eb\u003c/sup\u003e (50.9%)\u003c/p\u003e\u003cp\u003e19833 (49.1%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9817\u003csup\u003ea\u003c/sup\u003e (54.0%)\u003c/p\u003e\u003cp\u003e8351 (46.0%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3510\u003csup\u003ea\u003c/sup\u003e (55.6%)\u003c/p\u003e\u003cp\u003e2806 (44.4%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1698\u003csup\u003ea\u003c/sup\u003e (56.4%)\u003c/p\u003e\u003cp\u003e1313 (43.6%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e46809\u003c/p\u003e\u003cp\u003e41926\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e52.8%\u003c/p\u003e\u003cp\u003e47.2%\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAll\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20809 (23.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e40431 (45.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e18168 (20.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e6316 (7.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e3011 (3.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e88735\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e100%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTooth-level\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\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTooth type\u003c/p\u003e\u003cp\u003eAnterior teeth\u003c/p\u003e\u003cp\u003ePremolars\u003c/p\u003e\u003cp\u003eMolars\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3683\u003csup\u003ea\u003c/sup\u003e (12.6%)\u003c/p\u003e\u003cp\u003e8587\u003csup\u003ea\u003c/sup\u003e (29.4%)\u003c/p\u003e\u003cp\u003e16912\u003csup\u003ea\u003c/sup\u003e (58.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7943\u003csup\u003ea\u003c/sup\u003e (12.6%)\u003c/p\u003e\u003cp\u003e20247\u003csup\u003eb\u003c/sup\u003e (32.2%)\u003c/p\u003e\u003cp\u003e34658\u003csup\u003eb\u003c/sup\u003e (55.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7153\u003csup\u003eb\u003c/sup\u003e (24.5%)\u003c/p\u003e\u003cp\u003e10169\u003csup\u003ec\u003c/sup\u003e (34.8%)\u003c/p\u003e\u003cp\u003e11886\u003csup\u003ec\u003c/sup\u003e (40.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3503\u003csup\u003ec\u003c/sup\u003e (36.6%)\u003c/p\u003e\u003cp\u003e3456\u003csup\u003ec\u003c/sup\u003e (36.1%)\u003c/p\u003e\u003cp\u003e2624\u003csup\u003ed\u003c/sup\u003e (27.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2313\u003csup\u003ed\u003c/sup\u003e (51.8%)\u003c/p\u003e\u003cp\u003e1395\u003csup\u003ea,b\u003c/sup\u003e (31.2%)\u003c/p\u003e\u003cp\u003e758\u003csup\u003ee\u003c/sup\u003e (17.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e24595\u003c/p\u003e\u003cp\u003e43854\u003c/p\u003e\u003cp\u003e66838\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e18.2%\u003c/p\u003e\u003cp\u003e32.4%\u003c/p\u003e\u003cp\u003e49.4%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTooth location\u003c/p\u003e\u003cp\u003eMaxilla\u003c/p\u003e\u003cp\u003eMandible\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e16696\u003csup\u003ea\u003c/sup\u003e (57.2%)\u003c/p\u003e\u003cp\u003e12486 (42.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e35589\u003csup\u003ea,b\u003c/sup\u003e (56.6%)\u003c/p\u003e\u003cp\u003e27259 (43.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e16269\u003csup\u003eb\u003c/sup\u003e (55.7%)\u003c/p\u003e\u003cp\u003e12939 (44.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5358\u003csup\u003ea,b\u003c/sup\u003e (55.9%)\u003c/p\u003e\u003cp\u003e4225 (44.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2296\u003csup\u003ec\u003c/sup\u003e (51.4%)\u003c/p\u003e\u003cp\u003e2170 (48.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e76208\u003c/p\u003e\u003cp\u003e59079\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e56.3%\u003c/p\u003e\u003cp\u003e43.7%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNature of RC opening\u003c/p\u003e\u003cp\u003ePlanned\u003c/p\u003e\u003cp\u003eEmergency\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e26375\u003csup\u003ea\u003c/sup\u003e (89.4%)\u003c/p\u003e\u003cp\u003e3133 (10.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e56772\u003csup\u003eb\u003c/sup\u003e (90.4%)\u003c/p\u003e\u003cp\u003e5998 (9.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e26534\u003csup\u003ec\u003c/sup\u003e (91.4%)\u003c/p\u003e\u003cp\u003e2511 (8.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e8856\u003csup\u003ed\u003c/sup\u003e (92.7%)\u003c/p\u003e\u003cp\u003e694 (7.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4090\u003csup\u003ed\u003c/sup\u003e (92.7%)\u003c/p\u003e\u003cp\u003e324 (7.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e122627\u003c/p\u003e\u003cp\u003e12660\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e90.6%\u003c/p\u003e\u003cp\u003e9.4%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOperator\u003c/p\u003e\u003cp\u003eGeneral dentist\u003c/p\u003e\u003cp\u003eEndodontist\u003c/p\u003e\u003cp\u003eGeneral dentist in purchased service\u003c/p\u003e\u003cp\u003eDental student\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9071\u003csup\u003ea\u003c/sup\u003e (32.8%)\u003c/p\u003e\u003cp\u003e825\u003csup\u003ea\u003c/sup\u003e (3.0%)\u003c/p\u003e\u003cp\u003e17068\u003csup\u003ea\u003c/sup\u003e (61.7%)\u003c/p\u003e\u003cp\u003e693\u003csup\u003ea\u003c/sup\u003e (2.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e19835\u003csup\u003ea\u003c/sup\u003e (33.1%)\u003c/p\u003e\u003cp\u003e1787\u003csup\u003ea\u003c/sup\u003e (3.0%)\u003c/p\u003e\u003cp\u003e36556\u003csup\u003ea\u003c/sup\u003e (61.0%)\u003c/p\u003e\u003cp\u003e1743\u003csup\u003eb\u003c/sup\u003e (2.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e8234\u003csup\u003eb\u003c/sup\u003e (30.0%)\u003c/p\u003e\u003cp\u003e1020\u003csup\u003eb\u003c/sup\u003e (3.7%)\u003c/p\u003e\u003cp\u003e16711\u003csup\u003ea\u003c/sup\u003e (60.8%)\u003c/p\u003e\u003cp\u003e1523\u003csup\u003ec\u003c/sup\u003e (5.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2782\u003csup\u003eb\u003c/sup\u003e (31.1%)\u003c/p\u003e\u003cp\u003e436\u003csup\u003ec\u003c/sup\u003e (4.9%)\u003c/p\u003e\u003cp\u003e5062\u003csup\u003eb\u003c/sup\u003e (56.5%)\u003c/p\u003e\u003cp\u003e673\u003csup\u003ed\u003c/sup\u003e (7.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2233\u003csup\u003ec\u003c/sup\u003e (53.6%)\u003c/p\u003e\u003cp\u003e177\u003csup\u003eb,c\u003c/sup\u003e (4.3%)\u003c/p\u003e\u003cp\u003e1542\u003csup\u003ec\u003c/sup\u003e (37.0%)\u003c/p\u003e\u003cp\u003e212\u003csup\u003ec\u003c/sup\u003e (5.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e42155\u003c/p\u003e\u003cp\u003e4245\u003c/p\u003e\u003cp\u003e76939\u003c/p\u003e\u003cp\u003e4844\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e32.9%\u003c/p\u003e\u003cp\u003e3.3%\u003c/p\u003e\u003cp\u003e60.0%\u003c/p\u003e\u003cp\u003e3.8%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAll\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e29182 (46,2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e62848 (46.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e29208 (21.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e9583 (7.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e4466 (3.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e135287\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e100%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"9\"\u003e*Not included in other numbers\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\n\u003ch3\u003eFrequency of nsRCT in different tooth types\u003c/h3\u003e\n\u003cp\u003eNsRCTs were mostly performed to molars and premolars. In maxilla, first and second molars were the most common individual teeth to have nsRCT. First upper molars counted for 24.8% of all the upper teeth, followed by second premolars (22.7%) and second molars (13.5%). Anterior teeth had less often nsRCT compared to posterior teeth. In mandible, first and second molars were together the most susceptible for nsRCT. First lower molars had 41.2% of nsRCTs of all the lower teeth. In addition, lower second molars and second premolars were frequently subject to nsRCT. Lower anterior teeth had less nsRCTs than the lower posterior teeth. In this dataset, tooth 46 had the most nsRCTs of the whole dentition representing 9.2% of all the cases. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e visualize the distribution of nsRCTs in upper and lower teeth. Comparing nsRCT by tooth type and operator, we found that molars were more often treated than anterior teeth by both endodontists and group of GDs, dentists in purchased service and dental students (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). but mostly by GDs in purchased service (64,7% of all molar teeth). In percentages, endodontists compared to other operators performed similar proportion of nsRCTs on molar teeth (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Adults\u0026rsquo; upper and lower teeth with identified as having at least one completed nsRCT (first or further treatment) during our study period 2002\u0026ndash;2017 in Helsinki PDS.\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\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\u003eNsRCT on different tooth types by operators between 2002 and 2016. Chi-square test was used. Each subscript letter indicates a subset of tooth categories within operator which do not differ significantly from other groups with Bonferroni correlation. Percentages indicate the proportion of treated teeth in each age category by operator.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOperaror\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAnterior\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePremolars\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMolars\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAll\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003en (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003en (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003en (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEndodontist\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1296\u003csup\u003ea\u003c/sup\u003e (30.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1106\u003csup\u003eb\u003c/sup\u003e (26.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1843\u003csup\u003eb\u003c/sup\u003e (43.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e4245\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOthers\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21845\u003csup\u003ea\u003c/sup\u003e (17.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e40388\u003csup\u003eb\u003c/sup\u003e (32.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e61705\u003csup\u003eb\u003c/sup\u003e (49.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e123938\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAll\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e23141\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e41494\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e63548\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e128183\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eBased on our data, the volume of nsRCTs increased slighly in Helsinki PDS between 2002\u0026ndash;2017. Annual number of nsRCTs ranged from the lowest (n\u0026thinsp;=\u0026thinsp;6 140) in 2002 to the highest (n\u0026thinsp;=\u0026thinsp;10 108) in 2010. At total, 135 287 teeth were assessed statistically in this study. In 2007, a sudden drop in the amount of performed nsRCTs might be related to beginning of the purchased service. And if year 2003 would have been the starting point in our data, there would have been almost no change in the trend line. Though, before a law reform in 2002, dental care in PDS was age restricted, leading to a situation where only special-need groups of adults had access to public dental care [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. It is important to note that the positive trend line was not statistically significant. Interestingly, 30 921 (22,9%) teeth were found to have only dental code for root canal opening, but without obturation. Part of this could be explained by the fact that patients have had root canal filling in private sector rather than in Helsinki PDS even thought it is not unusual that RCTs are not completed [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn the study by Linden et al. 2020 [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] where data was gathered from five PDS in Southern Finland in the period of 2001\u0026ndash;2013, endodontic treatments had statistically highly significant increasing trend among 18-39-year-olds. However, the volume of endodontic treatments was found to have a descending trend in both public and private dental care over an 11-year period in the city of Helsinki, overlapping partly with our period of investigation [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Though, endodontic treatments included other procedures than primary nsRCTs in both studies. And their data was aggregated into 5-year patient age groups, possibly hiding sociodemographic changes in the population. Also, number of RCTT has been found to be decreasing in private sector, from 83 241 in 2012 to 61 188 in 2017 [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. In turn, prevalence of RCTT for Danish adults with baseline age of 20 or older in three consecutive examinations were 51%, 57% and 59% in years 1997, 2003 and 2008, respectively [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. It is the expected finding since it was assessed from the same cohort followed in three consecutive years. Other similar cohort from Denmark shows coterminous results with prevalence of RCTT within adults aged 20\u0026ndash;64 years being 44.1% (2009), 45.9% (2014), 51.8% (2018) [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. For instance, in Oslo repeated cross-sectional study of 35-year-olds with an approximately 10-year interval showed the prevalence of root filled teeth as 50%, 53%, 24% and 23% in years 1973, 1984, 1993 and 2003 with decreasing trend [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The same decreasing trend was seen in Sweden between 1973 and 2013 in all age groups from 3 to 80 years [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Even though our data shows a slightly positive trend in annual nsRCTs, further conclusions are hard to draw. The prevalence of RCTT and the amount of annual RCT vary slightly in each study. Could this be due to differences in study methods or are there possibly less teeth extractions leading to growth of RCTT? In large nationwide observational study from Finland, the mean number of extractions per patient was 0.17 in 2012 and 0.18 in 2017 in private sector, not supporting the hypothesis of less extractions [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. However, other study found that in Helsinki PDS, rate of extractions grew in function of age and rate of endodontic treatments decreased even though the trend in extractions didn\u0026rsquo;t change over time [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Also, differences in healthcare systems complicate the comparison between studies. It is important to clarify that many studies discuss endodontic treatments in general, including retreatments and surgical procedures. As our study focuses on primary nsRCTs, this limits the comparative value to other studies.\u003c/p\u003e\u003cp\u003eIn our data, the age group of 30\u0026ndash;49 had the most nsRCTs (45.6% of all nsRCTs, n\u0026thinsp;=\u0026thinsp;40 431). Age was significantly associated with gender, tooth type, the nature of root canal opening, and operators. We found no statistical differences between sex. In private Finnish dental clinics, the weighted mean age of an endodontic patient was 53.6 years in 2012 and 55.9 years in 2017 [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. In our data, mean age at the time of root canal filling was 43.2 (SD 15.1). This is lower than for Fransson et al. 2016 (mean age 55, range 20\u0026ndash;102) which studied individuals from both public and private sector [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] or for Wigsten et al. 2019 (mean age 48.3, SD 16.4) [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] but similar to other study conducted at PDS in Finland [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Additionally, in our data the number of patients decreased constantly in every age category without any peaks in the oldest groups found in other studies [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. For example, the mean age of patients with AP varies globally between 26\u0026ndash;52 years [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Apical periodontitis is a slowly developing condition and can remain symptomless for long periods [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e], and for the oldest quartile of the population, extraction could be more often favored over endodontic treatment which could partly explain our results.\u003c/p\u003e\u003cp\u003eOur findings of nsRCTs performed in the Helsinki PDS, give also a good overall picture of the distribution of nsRCTs in a Finnish public dental care system. Most of the nsRCTs are performed by GDs, followed by GDs in the purchased service whose role in the public service has grown in the last 15 years. Endodontists\u0026rsquo; and dental students' proportion of all nsRCTs has been nearly unchanged, being 3.1% and 3.8% respectively. Due to changes in the patient record system in 2017, we don\u0026rsquo;t have data of the distribution of performed nsRCTs in that year. A great majority of the performed nsRCTs were planned in every age category. The proportion of emergency root canal openings were around 10% of all the openings for most of the age categories. When interpreting the statistics from emergency or planned nsRCT, it is crucial to keep in mind that the use of dental codes may vary between dentists. Part of adults with assessed need for nsRCT started as emergency care are referred to purchased service of the City, for planned treatments to be completed by general dentists. This practice of combining public and purchased service is due to disequilibrium of demand of oral health treatment and supplier capacity at PDS since the adult population has been given access to care without age restrictions. As we don\u0026rsquo;t know the exact reasons for emergency treatment, we suppose that they are related to trauma or acute pain due to inflammation of the pulp or periradicular conditions [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. It is important to note that the use of dental codes is not consistent within dentists, and other codes than those we used for calculations, could have been used.\u003c/p\u003e\u003cp\u003eWe found that both in maxilla and in mandible, posterior teeth have had more often nsRCT than the anterior teeth which is in line with few other studies [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e], but different from a study conducted in private sector in Finland [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. First upper and lower molars were the most treated teeth. First lower molars were found to be the most prevalent ones in terms of nsRCT as in previous studies [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. Cross-sectional study of over 20 000 teeth found that AP was most prevalent in the first upper molars in maxilla and in the first lower molars in mandible. Except for maxillary anterior teeth, the same study found also that the prevalence of AP was lower in anterior teeth of mandible [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. While AP is one of the main reasons for nsRCT, this might explain our findings. Molars might be more affected by caries and thus by pulpitis and AP, when anterior teeth are more susceptible to nsRCT due to trauma [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Molars' difficult position for brushing and more complex morphology might favor bacteria to cause decay in comparison to anterior teeth. Additionally, molars along with anterior teeth are the first ones to erupt which could be the reason they receive most of the treatments. In our study, upper anterior teeth had more nsRCTs than lower anterior teeth. These results are similar to few other studies [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. One of the reasons could be that they are the first teeth to get hit in a potential trauma. Additionally, we compared whether tooth groups differed by operators. We found that endodontists and other operators performed nsRCTs more on molars rather than anterior teeth which inverse to private sector in Finland [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Interestingly, group of GDs and dental student performed nsRCTs on molar teeth in almost half of the cases (49.8%). This is rather surprising as in some other countries GDs do not perform nsRCTs on molars as often as endodontists [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe strength of the present study is that data comes from a large practice-based database of Helsinki PDS. As public services are important part of Finland\u0026rsquo;s dental care, this study provides good insights of nsRCTs among adult population. The study design provides a reliable view of current clinical practice for almost two decades. As register-based study design at the same time is a weakness of this study because all results are based on registers recorded by dental operators in electronic patient record system. Thus, any missing or not recorded information is handled as it is.\u003c/p\u003e\u003cp\u003eThe observed association between age groups and spesific tooth types treated underscore the need for age-sensitive approaches in treatment planning and preventive care. The use of comprehensive register-based data demonstrates the value of longitudinal public health records and guiding evidence-based decision-making. However, limitations such as missing clinical details or socioeconomic variables suggest that future studies should aim to integrate richer datasets to provide a more holistic view of patient and treatment profiles.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eAn important number of nsRCTs are carried out by mainly general dentists in Helsinki PDS. The yearly amount of nsRCTs remained mainly unchanged during 16 years of observation time even with improved oral health of population. Significant differenced of amount of nsRCTs exists by adult\u0026rsquo;s age group and sex, as well as their tooth type and location. Special attention should be paid in amount of uncompleted nsRCTs. To our knowledge, this is the first study conducted in Nordic countries focusing solely on frequencies of nsRCTs, and patient-related factors (age, sex, tooth type, jaw) and operators at PDS for 16 years. Studying further on nsRCT based on clinical outcomes would be future area of interest.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eConflict of interest\u003c/h2\u003e\u003cp\u003eWe have no conflict of interest to disclose.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eWe have not received any funding for this article.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eMilo V\u0026auml;is\u0026auml;nen (MV), [[email protected]](mailto:[email protected]) : Writing, Editing, Data HandlingJussi Furuholm (JF), [[email protected]](mailto:[email protected]) : Conceptualization, Methodology, Writing, Data handlingUlla Palotie (UP), [[email protected]](mailto:[email protected]) : Reviewing, EditingTseveenjav Battsetseg (TB), [[email protected]](mailto:[email protected]) : Reviewing, Editing, Conceptualization, Supervision\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSuominen\u0026ndash;Taipale L, Nordblad A, Vehkalahti M, Aromaa A (eds) (2004) Suomalaisten aikuisten suunterveys: Terveys 2000 \u0026ndash;tutkimus. 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Int Dent J 52(3):125\u0026ndash;129. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/j.1875-595x.2002.tb00616.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1875-595x.2002.tb00616.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\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":"[email protected]","identity":"clinical-oral-investigations","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cloi","sideBox":"Learn more about [Clinical Oral Investigations](http://link.springer.com/journal/784)","snPcode":"784","submissionUrl":"https://submission.nature.com/new-submission/784/3","title":"Clinical Oral Investigations","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Root Canal Treatment, Endodontics, Retrospective Studies, Dental Pulp Diseases","lastPublishedDoi":"10.21203/rs.3.rs-7807867/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7807867/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAccording to population-based studies, 25% of the adults are estimated to need root canal treatment (RCT). As public dental services (PDS) play a crucial role in providing dental care, register-based studies offer valuable research-based data on magnitude of RCTs and characteristics of teeth and adults receiving such treatments.\u003c/p\u003e\u003cp\u003eObjective\u003c/p\u003e\u003cp\u003eThe objective of this retrospective register-based study was to assess the magnitude of non-surgical root canal treatments (nsRCTs) carried out in PDS of the City of Helsinki between 2002\u0026ndash;2017, and to describe characteristics of teeth and adults receiving nsRCT.\u003c/p\u003e\u003cp\u003eResults\u003c/p\u003e\u003cp\u003eA total number of 166 218 teeth were identified with root canal treatment code. Of these, 81,4% had completed nsRCT, and 18,6% were uncompleted. Younger adults and women received more frequently nsRCTs, compared to their older counterparts and men, respectively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). At tooth level, molars and teeth in upper jaw received more nsRCTs, compared to anterior teeth or premolars and teeth in lower jaw (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Most of the nsRCTs were started as planned treatment, compared to teeth with emergency opening, and were performed by general dentists (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003cp\u003eConclusion\u003c/p\u003e\u003cp\u003eOur study offers wide picture of magnitude of nsRCTs carried out in Helsinki PDS. The nsRCTs carried out in public health sector differed by sex, age, tooth type and operator. These results could be used in improving cost-effective treatment planning and development of the strategies regarding treatment path at PDS.\u003c/p\u003e","manuscriptTitle":"Non-surgical root canal treatments in Public Dental Sector: characteristics of patients and teeth from 16-year register-based study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-27 15:21:20","doi":"10.21203/rs.3.rs-7807867/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-08T17:10:30+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-08T08:52:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-01T11:13:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"287276093773019458709828752897285852593","date":"2026-02-26T11:35:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"200227666184810412322339583670487618436","date":"2026-02-23T10:22:55+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-13T07:01:29+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-10T03:49:52+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-10T03:49:34+00:00","index":"","fulltext":""},{"type":"submitted","content":"Clinical Oral Investigations","date":"2025-10-08T12:11:48+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"clinical-oral-investigations","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cloi","sideBox":"Learn more about [Clinical Oral Investigations](http://link.springer.com/journal/784)","snPcode":"784","submissionUrl":"https://submission.nature.com/new-submission/784/3","title":"Clinical Oral Investigations","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"a6256b18-7bdf-4741-9714-760aaec88f7b","owner":[],"postedDate":"October 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-04-27T16:11:30+00:00","versionOfRecord":{"articleIdentity":"rs-7807867","link":"https://doi.org/10.1007/s00784-026-06876-x","journal":{"identity":"clinical-oral-investigations","isVorOnly":false,"title":"Clinical Oral Investigations"},"publishedOn":"2026-04-24 16:00:00","publishedOnDateReadable":"April 24th, 2026"},"versionCreatedAt":"2025-10-27 15:21:20","video":"","vorDoi":"10.1007/s00784-026-06876-x","vorDoiUrl":"https://doi.org/10.1007/s00784-026-06876-x","workflowStages":[]},"version":"v1","identity":"rs-7807867","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7807867","identity":"rs-7807867","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}