Objective: The aim of the study was to analyze factors influencing the radiographic outcome of first-time endodontic treatment of teeth with periapical lesions. Methods: From March 2008 to October 2022, 804 cases of primary apical periodontitis with radiographically detectable lesions were treated conservatively by postgraduate students at the Department of Endodontics. A total of 437 patients had recall 11-48 months after completion. Post-operative and control radiographs of the teeth were scored by the periapical index (PAI) adjusted to define strict and lenient criteria for success. Patients' sex and age, the tooth treated, the number of visits, and several tooth- and treatment-related factors were registered and related to radiographic outcomes in bivariate and regression, with actual p levels recorded. Results: Overall success rate was 68% by strict and 83% by lenient criteria. In binary analyses, a high preoperative PAI score, older age, poorer periodontal status, tooth type (anterior teeth and premolars), and higher number of visits were negatively related to the outcome. Logistic regression analysis of the whole material confirmed an adverse effect on outcome by these factors. In particular, the number of visits (OR = 1.3, p = 0.003) and the initial PAI (OR = 1.9, p < 0.001) were the strongest predictors of reduced success. Conclusions: Outcome of treatment of primary apical periodontitis by postgraduate students was negatively affected by higher preoperative PAI score, higher patients' age, poorer periodontal status, and higher number of visits for completion. Clinical Relevance: This study provides clinically relevant insight into multiple prognostic factors that influence the outcome of primary root canal treatment in teeth with periapical lesions, including patient-related, tooth-related, and procedural variables. The results reflect real-world outcomes in a postgraduate clinical setting and confirm the favorable outcome of single-visit treatments found in randomized studies.

OBJECTIVES:Assess the effect of addition or replacement of bioactive glass (BG) on the physico-chemical, antibacterial and biological properties of radiopacified tricalcium silicate cement (TCS). METHODS:Four materials were tested: An experimental cement with 80 % TCS, 20 % zirconium oxide (TZ-base); two modified versions of TZ-base incorporating 20 % BG 45S5 either as TCS-replacement (TZ-bg-R) or addition (TZ-bg-A); and Biodentine (Septodont). Setting time was assessed using ISO 6876:2012 method. Materials were immersed in water or Dulbecco's modified eagle medium with 10 % fetal bovine serum (DMEM-sup). After seven days, water sorption and solubility were assessed using ISO 4049:2019 methods; water uptake and porosity were also calculated; leachate alkalinity and calcium release were assessed with a pH meter and inductively coupled plasma respectively; specimens were characterized with scanning electron microscopy, energy dispersive X-ray and X-ray diffraction analysis. At one-day, antibacterial properties of material surfaces and leachates were tested against Enterococcus faecalis and Staphylococcus epidermidis biofilms; leachate cytotoxicity and cytokine release were assessed with the 3-(4,5 dimethylthiazolyl-2-yl)-2,5-diphenyl tetrazolium bromide assay and an enzyme-linked immunosorbent assay. Regression models were fitted for all dependent variables. RESULTS:Compared to TZ-base, the BG-containing materials had overall increased water sorption, water uptake and porosity; decreased solubility in DMEM-sup; lower calcium release; and generally similar pH, antibacterial activity, cytotoxicity and cytokine release. All experimental cements were more cytotoxic than Biodentine, but the latter caused higher cytokine release. SIGNIFICANCE:The BG-incorporation whether added or replacing the cement decreased the solubility in clinically relevant media and did not deteriorate the antimicrobial and biological properties of the materials.

The placement of root filling materials aims to prevent the occurrence of post-treatment apical periodontitis following completion of endodontic treatment. Materials should possess properties that will not permit bacterial invasion and infection, namely excellent sealing ability and/or antibacterial properties. In root-end filling procedures or repair of root perforations, the root filling materials are placed in a particularly challenging clinical environment, as they interface with a relatively large area with the periradicular tissues. The biological properties of these materials are therefore of significant importance. The current review discusses the most widely used materials for endodontic surgery (i.e., root-end filling and perforation repair), with particular focus on their biological characteristics, namely antibacterial properties and interactions with host tissue cells, together with clinical studies. Properties of amalgam, glass ionomer cements (GICs), resin systems, zinc oxide eugenol-based cements and hydraulic calcium silicate cements (HCSCs), together with representative and well-researched commercial materials in the context of their use in endodontic surgery are presented. While the use of HCSCs seems to offer several biological advantages, together with addressing issues with the initial formulation in the most recent versions, materials with different chemical compositions, such as zinc oxide eugenol-based cements, are still in use and appear to provide similar clinical success rates to HCSCs. Thus, the significance of the currently available materials on clinical outcomes remains unclear.

The aim of this prospective cohort study was to compare the radiographic outcome of endodontic treatment and retreatment of teeth with apical periodontitis using either 1% sodium hypochlorite (NaOCl) or 2% chlorhexidine digluconate (CHX) for root canal irrigation. In the years from 2013 to 2015 standard irrigation varied by semester between NaOCl and CHX at the Department of Endodontics at the Faculty of Dentistry. During that time, 912 teeth received treatment for apical periodontitis in 744 patients, of whom 532 responded to the request for a 1-year follow-up. Only one tooth per person (the most distally located) were included; 285 teeth treated with NaOCl and 247 with CHX. One hundred cases were then randomly sampled from each irrigation group and analysed for outcome by periapical index (PAI) scoring using criteria for success, uncertain and failure. Clinical and other radiographic parameters were scored or recorded and analysed for associations with radiographic outcome using chi-square, ANOVA and regression analyses. Success rates (PAI score 1 or 2 at control) were nearly identical for the two irrigation liquids. The use of irrigating solution also did not significantly influence the outcome in chi-square analyses of subgroups of teeth or regression analyses with other variables included. Ordinal regression analysis established that preoperative lesion size or preoperative PAI score were significantly associated with outcome, and teeth in the mandible had significantly better outcomes than in the maxilla. No significant differences in the radiographic outcome using either 1% NaOCl or 2% CHX as irrigants were found. The outcome was better for teeth with small lesions or lower PAI scores at completion of treatment and for mandibular teeth.

AIM:The aim of this prospective cohort study was to compare the radiographic outcome of endodontic treatment and retreatment of teeth with apical periodontitis using either 1% sodium hypochlorite (NaOCl) or 2% chlorhexidine digluconate (CHX) for root canal irrigation.MATERIALS AND METHODS:In the years from 2013 to 2015 standard irrigation varied by semester between NaOCl and CHX at the Department of Endodontics at the Faculty of Dentistry. During that time, 912 teeth received treatment for apical periodontitis in 744 patients, of whom 532 responded to the request for a 1-year follow-up. Only one tooth per person (the most distally located) were included; 285 teeth treated with NaOCl and 247 with CHX. One hundred cases were then randomly sampled from each irrigation group and analysed for outcome by periapical index (PAI) scoring using criteria for success, uncertain and failure. Clinical and other radiographic parameters were scored or recorded and analysed for associations with radiographic outcome using chi-square, ANOVA and regression analyses.RESULTS:Success rates (PAI score 1 or 2 at control) were nearly identical for the two irrigation liquids. The use of irrigating solution also did not significantly influence the outcome in chi-square analyses of subgroups of teeth or regression analyses with other variables included. Ordinal regression analysis established that preoperative lesion size or preoperative PAI score were significantly associated with outcome, and teeth in the mandible had significantly better outcomes than in the maxilla.CONCLUSIONS:No significant differences in the radiographic outcome using either 1% NaOCl or 2% CHX as irrigants were found. The outcome was better for teeth with small lesions or lower PAI scores at completion of treatment and for mandibular teeth.

OBJECTIVES:Final root canal irrigation should ideally maintain the physicochemical stability of root canal sealers. We seek to assess the effect of contact with 2% chlorhexidine digluconate (CHX) on the physicochemical properties of AH Plus, BioRoot™ RCS, and Pulp Canal Sealer (PCS). METHODS:Mixed sealers were placed in cylindrical teflon molds and allowed to set for 1.5x the manufacturers' setting time. Half of the specimens had their free surface in contact with CHX for the first minute of their setting period. Solubility, radiopacity, surface roughness, microhardness and wettability of the sealers were assessed up to 28 days after setting. Elemental analysis of sealer surfaces and their leachates together with pH measurements were also performed. Appropriate parametric and non-parametric analysis with post hoc tests were performed (p < 0.05). RESULTS:Exposure to CHX had no effect on solubility and radiopacity of all sealers. CHX altered the surface roughness of PCS and BioRoot RCS (p < 0.05). Contact with CHX reduced the microhardness of AH Plus and PCS (p < 0.05). AH Plus was more hydrophilic after CHX contact, whereas PCS became more hydrophobic (p < 0.05). AH Plus and PCS surfaces appeared to adsorb CHX as exhibited by chlorine peaks after contact with CHX. Sealer leachates' alkalinity was not affected. CHX increased elution of silicon and zirconium for BioRoot and zinc for PCS leachates. SIGNIFICANCE:In our study, CHX affected sealers' physicochemical properties to various extents. Further studies are needed to confirm the obtained results by investigating various final irrigation strategies and correlating to biological properties.

Hovedbudskap Tannleger bør ha bedre kommunikasjon med pasientene om behandlingsmål og prognose, og henvise til spesialist til riktig tid uten forsinkelser for å oppnå optimalt behandlingsresultat. Forskning må ikke bare konsentrere seg om tekniske innovasjoner som kan gi kortsiktige fordeler for produsenter, men i større grad fokusere på variabler som kan ha betydning for resultater i kliniske langtidsstudier. Vi trenger bedre kunnskap for å forstå tannsmertemekanismer, håndtering av smertefølelse, og kontrollere og fjerne infeksjon. Studenter med kompetanse og evner til å lære å gi endodontisk behandling av høy kvalitet må rekrutteres av utdanningsinstitusjoner. Dette er en økende utfordring i et konkurranseutsatt arbeidsmarked. Man kan forutse at kostnadene for tannbehandling, inkludert endodonti, vil vise økt tredjepartsbetaling fra offentlige eller private forsikringsordninger. Dette vil nokså sikkert innebære at kost/nytte-vurderinger må gjennomgås i større bredde enn i dag.

AIMS To evaluate and compare the treatment outcome of root-filled teeth with apical periodontitis treated either non-surgically or by endodontic microsurgery, and to assess the influence of an intra-radicular post, clinical and demographic factors. METHODOLOGY Clinical and radiological data from 1157 patients with apical periodontitis in previously root-filled teeth treated by postgraduate students at the Department of Endodontics, University of Oslo, between September 2010 and January 2020 with recall data at least 11 months from completion were studied. Surgical cases were scored using the Rud/Molven criteria and grouped into success, uncertain or failure at control. Non-surgical cases were scored with the periapical index (PAI) and similarly grouped into success, uncertain or failure at control. Chi-square analyses were used for comparison of subgroups of teeth treated and logistic regression analyses for assessment of the influence of clinical variables. RESULTS Non-surgical retreatment was performed on 351 teeth and 107 teeth were treated with endodontic microsurgery, with overall success rates of 65.5% and 77.6%, respectively. The difference was statistically significant. Teeth with an intra-radicular post treated non-surgically (n=30) were successful in 73.3% of cases, whereas teeth with intra-radicular post treated with endodontic microsurgery (n=30) had a lower, 66.7% success rate. The distribution of tooth groups (anterior, premolar and molar) differed significantly between surgical and non-surgical cases, with maxillary anterior and premolar teeth more often treated surgically. Non-surgical retreatment cases were significantly influenced by patients' age (older patients had poorer outcome) and preoperative PAI score (negatively correlated with outcome). Surgical cases were not significantly influenced by the factors studied here. CONCLUSIONS The tooth type differed significantly for teeth treated by surgical versus non-surgical methods. Microsurgical treatment with apicectomy and retrograde filling showed significantly better treatment results than non-surgical retreatment of teeth with apical periodontitis, whereas treatment outcome in teeth with posts after non-surgical treatment tended to be better than after surgical treatment. Outcome of non-surgical retreatment was negatively influenced by older age and higher preoperative PAI score.

This study assessed the antibacterial characteristics of the dentin/material interface and dentin surfaces exposed to experimental hydraulic calcium silicate cement (HCSC) with or without bioactive glass (BG) replacement (20% or 40%) or mixed with a silver nanoparticle (SNP) solution (1 or 2 mg/mL), and Biodentine, TotalFill BC RRM putty and Intermediate Restorative Material (IRM). Human root dentin segments with test materials were assessed at 1 or 28 days. In one series, the specimens were split to expose the dentin and material surfaces. A 24 h direct contact test was conducted against three-day established Enterococcus faecalis and Pseudomonas aeruginosa monospecies biofilms. In another series, the dentin/material interface of intact specimens was exposed to biofilm membranes for 3 days and the antibacterial activity was assessed via confocal microscopy. The interface was additionally characterised. All one-day material and dentin surfaces were antibacterial. Dentin surfaces exposed to HCSC with 40% BG-replacement, Biodentine and IRM had decreased antibacterial properties compared to those of the other cements. The HCSC mixed with a 2 mg/mL SNP solution had the highest antimicrobial effect in the confocal assay. The interfacial characteristics of HCSCs were similar. The test materials conferred antibacterial activity onto the adjacent dentin. The BG reduced the antibacterial effect of dentin exposed to HCSC; a 2 mg/mL SNP solution increased the antibacterial potential for longer interaction periods (three-day exposure).

Headlines Dental practitioners should have better communication with the patients about treatment goals and prognosis or refer to a specialist at the appropriate time without delays to achieve optimal treatment outcome. Research must not only concentrate on innovations which may interest stakeholders with short-term benefits but on randomized studies, to compare with existing materials, to prove their superiority in clinical outcomes. We need better knowledge to understand dental pain mechanisms, management of pain sensation, control and eradicate infection. Recruitment of students with outstanding performances by educational institutions in a competitive job market is a challenge that needs to be addressed. The cost of dental treatment, including endodontics, may call for increased third-party payment by government or private insurance schemes. By studying the cost-effectiveness of treatment, current systems may need to be reviewed.

This study investigated the role of aging and changes in environmental conditions on selected properties of a prototype radiopacified calcium silicate-based cement (TZ-base) with or without incorporation of silver nanoparticles or bioactive glass, and two commercial materials, Biodentine and intermediate restorative material. Materials were immersed in ultrapure water or fetal bovine serum for 28 days and were characterized with scanning electron microscopy and energy dispersive x-ray analysis. Immersion media were either replaced weekly or not replenished at all and were assessed for alkalinity and calcium release after 1, 7, 14, 21, and 28 days; antibacterial effect against 2-day monospecies biofilms; and cytotoxicity by the 3-(4,5 dimethylthiazolyl-2-yl)-2,5-diphenyl tetrazolium bromide assay after 1, 7, or 28 days. Alkalinity, calcium release, antibacterial activity, and cell cytotoxicity increased over time when the medium was not changed but decreased with medium replenishment. Immersion in fetal bovine serum resulted in lower alkalinity, less bactericidal properties, and lower cytotoxicity of prototype cements and Biodentine than did water immersion. Biodentine and 20% bioactive glass-containing cement had overall lower alkalinity, calcium release, and antibacterial activity than TZ-base, and Biodentine was less cytotoxic than TZ-base. In conclusion, exposure conditions and cement modifications significantly affected materials' leaching properties. Exposure conditions warrant consideration when evaluating cements' clinical properties.

To evaluate and compare the treatment outcome of root filled teeth with apical periodontitis treated either non-surgically or by endodontic microsurgery, and to assess the influence of an intra-radicular post, clinical and demographic factors. Clinical and radiological data from 1157 patients with apical periodontitis in previously root filled teeth treated by postgraduate students at the Department of Endodontics, University of Oslo, between September 2010 and January 2020 with recall data at least 11 months from completion were studied. Surgical cases were scored using the Rud/Molven criteria and grouped into success, uncertain or failure at control. Non-surgical cases were scored with the periapical index (PAI) and similarly grouped into success, uncertain or failure at control. Chi-square analyses were used for comparison of subgroups of teeth treated and logistic regression analyses for assessment of the influence of clinical variables. Non-surgical retreatment was performed on 351 teeth and 107 teeth were treated with endodontic microsurgery, with overall success rates of 65.5% and 77.6%, respectively. The difference was statistically significant. Teeth with an intra-radicular post treated non-surgically ( n  = 30) were successful in 73.3% of cases, whereas teeth with intra-radicular post treated with endodontic microsurgery ( n  = 30) had a lower, 66.7% success rate. The distribution of tooth groups (anterior, premolar and molar) differed significantly between surgical and non-surgical cases, with maxillary anterior and premolar teeth more often treated surgically. Non-surgical retreatment cases were significantly influenced by patients' age (older patients had poorer outcome) and pre-operative PAI score (negatively correlated with outcome). Surgical cases were not significantly influenced by the factors studied here. The tooth type differed significantly for teeth treated by surgical versus non-surgical methods. Microsurgical treatment with apicectomy and retrograde filling showed significantly better treatment results than non-surgical retreatment of teeth with apical periodontitis, whereas treatment outcome in teeth with posts after non-surgical treatment tended to be better than after surgical treatment. Outcome of non-surgical retreatment was negatively influenced by older age and higher pre-operative PAI score.

Abstract Objectives The aim of this study was to compare periapical status transitions in teeth after post placement compared with other post-endodontic treatments in root-filled teeth. Material and methods This retrospective longitudinal radiographic study included radiographs of 284 patients with root filled and restored teeth with composite fillings (Endo-fill group, n = 100), crown or fixed prosthesis (Endo-crown group, n = 82) or post and core restorations (Endo-post group, n = 102). All post and core restorations were made of gold alloy. The radiographs taken at the end of endodontic treatment, at the end of post-endodontic treatment and at least 8 months after post-endodontic treatment were evaluated. Post-operative periapical status was assessed according to the periapical index (PAI) and all teeth included in the study had no apical periodontitis preoperatively. Multi-state Markov analysis was used to assess periapical status transitions among the treatment groups. Results Of 284 root-filled teeth without apical periodontitis at baseline, 7.7% developed clear apical pathology within a minimum of 8 months observational period. In the Endo-post group 11 (10.78%) teeth transited from Healthy (PAI 1) to Disease (PAI 2-4) state compared with eight (9.75%) in the Endo-crown group and four (4%) in the Endo-fill group. The transition probabilities from Healthy (PAI 1) to Mild diseased (PAI 2) were 17.5% in the Endo-post group, 13.1% in the Endo-crown group and 5.3% in the Endo-fill group. Multivariate analysis showed that teeth in the Endo-fill group had 60% lower hazard to transit from Healthy (PAI 1) to Mild diseased (PAI 2) state [HR 0.40; 95% CI 0.12, 0.94]. A period exceeding 8 months between the end of the endodontic treatment and prosthetic treatment significantly increased the hazard of disease progression by three times compared with a period of ≤8 months [HR 3.16; 95% CI 1.06, 9.42]. Conclusions Teeth without radiographic lesions at baseline and restored with posts had higher hazard to transit from healthy to diseased periapical status compared with teeth restored with composite restorations. Controlled clinical trials with longer follow-up periods are needed to validate these findings.

OBJECTIVE:Assess the biological and physicochemical properties of AH Plus, BioRoot RCS and Pulp Canal Sealer (PCS) leachates with and without chlorhexidine (CHX). METHODS:The sealers were studied in no contact and 1-minute contact with CHX. For biological properties (antibacterial activity and cytotoxicity), leachates were formed in saline of freshly mixed, 1-, 7- and 28 days set sealers. The antibacterial properties of sealer leachates were investigated for planktonic and biofilm growth of E. faecalis, S. mutans, S.epidermidis and S.aureus. The 3-(4,5 dimethylthiazolyl-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate murine fibroblast cell viability after exposure to the leachates. The physical properties (water uptake, sorption, solubility, porosity, surface characteristics) of sealers and the pH of the immersion liquid (saline or distilled water) were also assessed over a 28-days period. RESULTS:CHX improved the antibacterial properties of the sealer leachates and reduced cell viability for all sealer leachates, except for freshly mixed PCS. BioRoot RCS leachates presented the highest antibacterial properties and cell viability with and without CHX contact. PCS was the material most affected by CHX in terms of physical properties, whereas for AH Plus, solubility was increased. CHX did not affect the physical properties of BioRoot RCS, except for solubility that was decreased. CHX contact did not change sealers' alkalinity in distilled water whereas it increased it for AH Plus and BioRoot RCS in saline. SIGNIFICANCE:CHX improved the antibacterial efficacy of sealer leachates and either compromised or did not affect cell viability. CHX affected to various extent sealers' physicochemical properties.

Assess whether sodium hypochlorite (NaOCl) or chlorhexidine (CHX) and two irrigation protocols may alter the antibacterial properties of dentine and three endodontic sealers using a novel ex vivo tooth model. Prior to antibacterial testing, the tooth model was validated by means of scanning electron microscopy (SEM) to evaluate the separation between dentine and sealer surfaces. Root blocks prepared from extracted human roots were pre-treated with 17% EDTA + 0.9% saline and subsequently treated with 1% NaOCl (G1), 2% CHX (G2) or no irrigant (G3). Two irrigation protocols were further investigated, “1% NaOCl + 17% EDTA” (P1) and “1% NaOCl + 17% EDTA + 2% CHX” (P2). Following irrigation, the root blocks were either filled with AH Plus, BioRoot RCS and Pulp Canal Sealer (PCS), or left empty. All groups were incubated for 1, 7 and 28 days. Direct contact tests for planktonic E .  faecalis and 48 h E .  faecalis biofilms were performed at the level of dentine and sealer surfaces. Statistical analysis was performed on the bacterial survival between irrigants (G1, G2 and G3) and between irrigation protocols (P1 and P2); p  < .05. The model was considered reproducible as SEM examination of dentine samples indicated consistent separation between dentine and sealer surfaces. Irrigation with CHX (G2) and irrigation protocol P2 enhanced the antibacterial properties of dentine without sealer application as well as dentine in contact with all three sealers tested, especially against planktonic E .  faecalis . G2 and P2 also improved the antibacterial effect of AH Plus surfaces for all three incubation times. No irrigation groups (G1, G2) or irrigation protocols (P1, P2) altered the antibacterial properties of BioRoot RCS surfaces against planktonic bacteria or biofilms. Only BioRoot RCS surfaces eliminated the planktonic E .  faecalis in all irrigation groups (G1, G2, G3) and protocols (P1, P2) investigated whilst PCS surfaces eliminate E .  faecalis in biofilms in all groups up to 7 days. The tooth model was reproducible. CHX improved the antibacterial activity upon both sealer and dentine surfaces. Amongst sealers, BioRoot RCS was less affected by NaOCl and CHX, and exhibited high antibacterial properties regardless the irrigation applied.

To investigate the effect of inclusion of silver nano-particles (SNP) or bioactive glass (BG) on the surface characteristics and bacterial adhesion of prototype tricalcium silicate (TCS)–based cements alongside two commercial cements, under different aging periods and exposure conditions. A basic formulation of radio-opacified TCS without (TZ-base) and with additions of SNP (0.5, 1, or 2 mg/ml) or BG (10 or 20

Aim This cross-sectional study aimed to investigate the prevalence of apical periodontitis (AP) and root-filled teeth in a 65-year-old population in Oslo, Norway, and to investigate associations of pathosis and endodontic treatment with selected individual risk indicators and technical quality of root fillings. Material and methods A random sample of 450 65-year-olds in Oslo answered a questionnaire and underwent a clinical and radiological examination (52% men and 48% women). Periapical radiographs were taken of all root-filled teeth and of teeth with apical radiolucency, and periapical status was evaluated using the Periapical Index. Apex-to-filling distance and homogeneity were assessed for all root fillings. Analyses on individual level and tooth level were performed. The outcome variables were ‘non-root-filled tooth with AP’ (‘untreated AP’), ‘root-filled tooth’, and 'root-filled tooth with AP’. The explanatory variables were gender, education, dental attendance pattern, smoking, remaining teeth (n), tooth group, and root filling quality. Chi-square test and logistic regression analyses were used to assess the associations between outcome variables and explanatory variables. The level of significance was set to p < 0.05. Results The mean number of remaining teeth was 26 (SD: 4). AP was present in 45% of the individuals. Sixteen percent of the individuals had untreated AP and 38% had at least one root-filled tooth with AP. Sixty-six percent of the individuals had one or more root-filled teeth. Untreated AP was significantly associated with a decreasing number of remaining teeth and smoking. All the outcome variables were significantly more prevalent in molars compared with premolars and anterior teeth. Thirty-five percent of the root-filled teeth had AP, and AP was more prevalent in teeth with too short apex-to-filling distance (53%) or unsatisfactory homogeneity (46%). Conclusions The remaining number of teeth was high, and AP and root-filled teeth were prevalent in the present young-elderly population. A notable amount of untreated AP was observed, especially in smokers. The findings in the present study indicate a substantial need for dental care associated with endodontic conditions in the future elderly.

To investigate the effect of a continuing education course on technical quality and treatment outcome for root filled permanent teeth in Møre and Romsdal County, Norway. Fifty-two dentists employed in the Public Dental Service in Møre and Romsdal county, Norway, completed a two-day continuing education course in root canal treatment. Periapical radiographs of root filled teeth treated before and after the course, with at least one-year follow-up were identified and scored for technical quality and periapical status. Technical root filling quality was assessed by density and length and the treatment outcome by PAI scores. Treatment information was achieved from the county's electronic dental record system. Information regarding the dental practitioners' background and treatment procedure routines was collected by a questionnaire. Descriptive statistics analyses and mixed-effect logistic regression analyses were performed to evaluate the effect of the course. Radiographs were available for 224 teeth root filled before and for 221 teeth after the course. The proportion of teeth with adequate root filling quality was significantly lower after the course ( p = .006), associated mainly with short root fillings ( p < .001). No significant differences were observed in treatment outcome. There were, however, large differences in treatment outcome amongst subgroups of dentists. Further, there was evidence of effect modification by the continuing education course on periapical outcome by patient's age ( p interaction = .0023) suggesting that teeth in patients ≤18 years healed relatively better post-course compared to patients >18 years. A two-day continuing education course in root canal treatment attended by Public Dental Service dentists in Norway did not improve the technical quality of root fillings or periapical status associated with root filled teeth.