Removal of fiber posts using conventional versus guided endodontics: a comparative study of dentin loss and complications.

OBJECTIVES: To compare the efficacy of fiber post removal using conventional (CONV) versus guided endodontics (GE) in terms of dentin loss, residual resin material, procedural errors, and working time in vitro. MATERIAL AND METHODS: Ninety human central incisors were root-filled and scanned by micro-computed tomography (CT), then restored with fiber posts and composite. Twenty-four sets of teeth with up to four human maxillary central incisors were fabricated and divided into three groups: conventional post removal by a general dentist (CG) or endodontology specialist (CS) and guided endodontics (GE) by a general dentist, yielding 30 teeth per operator and group. After treatment, the prepared access cavities were volumetrically assessed by micro-CT. Statistical significance was evaluated by one-way analysis of variance followed by post hoc comparisons with Tukey's HSD test and Pearson's chi-squared test for independence. RESULTS: Both CONV and GE resulted in dentin loss and residual resin material. CS resulted in more dentin loss and less residual resin material than CG and GE (p < .05). All groups had some deviations from the original root canal but no perforations. The shortest working time was observed in the GE group. CONCLUSIONS: Compared to the conventional freehand technique, GE resulted in significantly less radicular dentin loss, a few deviations but no perforations. CLINICAL RELEVANCE: Guided endodontics can improve the speed and safety of fiber post removal without root perforation.

Accuracy of Selective Enamel Etching: A Computer-assisted Imaging Analysis.

OBJECTIVE: To assess the accuracy of selective enamel etching (SEE) in a laboratory setup simulating clinical conditions. METHODS AND MATERIALS: A model with permanent human teeth was fabricated. It included a first mandibular molar with a mesio-occlusal-distal inlay preparation, a maxillary central incisor, and a canine with a class IV and class V cavity, respectively. Two dentists (with 1 year and 10 years work experience) repeatedly (n=10 per cavity) performed SEE with a custom gel that had identical rheological properties as a commercially available phosphoric acid etchant. An intraoral scanner was used for image acquisition. To assess the accuracy of SEE, special software was used (OraCheck, Cyfex, Zurich, Switzerland). Two independent investigators analyzed baseline scans and scans taken of the cavities while the gel was in place. The statistical analysis comprised t-tests, Pearson correlation, and analysis of variance (α=0.05). RESULTS: The level of accuracy, whose average values ranged from 61.1% to 87.0%, showed significant differences between teeth, with the highest level observed in the class V cavity, followed by the class II inlay preparation and the class IV cavity (p<0.001). Across the cavities, no significant correlation was observed between the application time and the accuracy of SEE (p=0.07). CONCLUSION: This laboratory study suggests that inadvertent conditioning of dentin adjacent to enamel may be common during SEE. Investigations involving larger samples of dentists are needed to corroborate this finding.

European Society of Endodontology position statement: endodontic management of traumatized permanent teeth.

This position statement represents a consensus of an expert committee convened by the European Society of Endodontology (ESE) on the endodontic management of traumatized permanent teeth. A recent comprehensive review with detailed background information provides the basis for this position statement (Krastl et al. 2021, International Endodontic Journal, https://doi.org/10.1111/iej.13508). The statement is based on current scientific evidence as well as the expertise of the committee. Complementing the recently revised guidelines of the International Association of Dental Traumatology, this position statement aims to provide clinical guidance for the choice of the appropriate endodontic approach for traumatized permanent teeth. Given the dynamic nature of research in this area, this position statement will be updated at appropriate intervals.

Endodontic management of traumatized permanent teeth: a comprehensive review.

The pulp plays a key role in the treatment of traumatic dental injuries (TDIs) and is strongly associated with the outcome, particularly in severe cases. A correct pulp diagnosis is essential as it forms the basis for developing the appropriate management strategy. However, many TDIs are complex, and their treatment requires a profound knowledge of the physiological and pathological responses of the affected tissues. This comprehensive review will look at the dentine-pulp complex and its interaction with the surrounding tissues following TDIs. The literature up to 2020 was reviewed based on several searches on PubMed and the Cochrane Library using relevant terms. In addition to the recently revised guidelines of the International Association of Dental Traumatology, this article aims to provide background information with a focus on endodontic aspects and to gather evidence on which a clinician can make decisions on the choice of the appropriate endodontic approach for traumatized permanent teeth.

Fluorescence-aided Composite Removal in Directly Restored Permanent Posterior Teeth.

AIM: The aim of this study was to quantitatively compare conventional composite removal and composite removal supported by the fluorescence-aided identification technique (FIT) regarding the completeness, selectivity, and duration of the procedure in directly restored permanent posterior teeth. METHODS AND MATERIALS: Two operators removed standardized direct class II composite restorations (n=32 per operator) in human tooth models under simulated clinical conditions. According to a randomized allocation scheme, removal was performed with either the conventional technique (contra-angle handpiece) or supported by FIT. The duration of each removal procedure was recorded. The completeness and selectivity were volumetrically assessed through superimposition of three-dimensional surface scans. Statistical significance was tested by examining the overlap of 95% confidence intervals (CI). Multiple comparison was performed with Tukey tests for each variable. RESULTS: Compared with the conventional technique, composite removal with FIT was faster (329 seconds [95% confidence interval (CI): 268-390 seconds] vs 179 seconds [95% CI: 150-208 seconds]), generated less tooth substance loss (4.53 mm3 [95% CI: 3.77-5.30 mm3] vs 2.77 mm3 [95% CI: 2.11-3.43 mm3]), and left behind less composite residue (1.58 mm3 [95% CI: 1.23-1.94 mm3] vs 0.53 mm3 [95% CI: 0.39-0.67 mm3]). CONCLUSION: Within the limitations of this in vitro study, FIT facilitated the selective and expeditious removal of tooth-colored composites in directly restored posterior teeth.

Evaluation of the accuracy of nine electronic apex locators by using Micro-CT.

AIM: To determine the accuracy of locating the apical constriction using apex locators. METHODOLOGY: Extracted teeth were micro-CT scanned preoperatively to localize the apical constriction. Electronic length measurements of 91 root canals were made using nine electronic apex locators (EAL) connected to a mounting model. Distances from the major foramen were recorded at each scale bar of the EALs, and a file was fixed in the canal at a position indicated by each EAL to be the apical constriction. A second micro-CT scan was conducted, and distances from the file tip to constriction and major foramen were calculated for each EAL. The accuracy of EALs was determined with a tolerance of 0.1, 0.25, 0.5 and 1 mm, and the 95% confidence interval was used to compare the EALs. A rank analysis was performed in which measurements beyond the major foramen were considered as inaccurate. RESULTS: Regardless of the type of teeth, there was no significant difference in the accuracy of determining the apical constriction and major foramen between the nine EALs within a tolerance of ±0.5 mm and 1 mm, but there was a significant difference for the tolerances of ±0.1 and 0.25 mm. The highest ranks close to the constriction (98% and 94%) and to the major foramen (86% and 73%) were observed in Dentaport ZX and Elements Diagnostic Unit, respectively. Overestimation of working length beyond the major foramen was observed in all EALs (5% to 71%) when the scale for the major foramen, as recommended by the manufacturers, was used. However, when the scale for the constriction was used, only 3% of the measurements were beyond the major foramen. CONCLUSION: Electronic apex locators were able to determine the apical constriction. Using EALs to determine the major foramen led to overestimation of the working length. Therefore, it may be recommended to use the EAL scale of the constriction.

Microguided Endodontics: a method to achieve minimally invasive access cavity preparation and root canal location in mandibular incisors using a novel computer-guided technique.

AIM: To present a novel miniaturized and minimally invasive treatment approach for root canal localization in mandibular incisors with pulp canal calcification and apical periodontitis. SUMMARY: A 51-year-old male patient presented with pain from his mandibular incisors. The patient had a history of severe dental trauma over 30 years ago. Both mandibular central incisors (teeth 31, 41) were tender to percussion and had a yellowish discoloration. They did not respond to thermal and electrical sensitivity tests. Two periapical radiographs from different projections revealed severe pulp canal calcifications and signs of periapical periodontitis. To facilitate the 'Microguided Endodontics' technique, a CBCT and an intra-oral surface scan were aligned using special software. This allowed the virtual planning of optimal access cavities up to the apical third of the root. In this technique, a 3D-printed template guides a customized drill to the orifice of the root canal. After negotiation of the root canals, conventional root canal treatment was performed. This case report demonstrates that minimally invasive and apically extended access cavities are feasible in mandibular incisors with this technique. KEY LEARNING POINTS: The 'Microguided Endodontics' technique is a safe and minimally invasive method for root canal location and prevention of technical failures in anterior teeth with pulp canal calcification.

Reliability of a Fluorescence-aided Identification Technique (FIT) for detecting tooth-colored restorations: an ex vivo comparative study.

OBJECTIVE: The aim of the study was to compare the diagnostic predictive values of a Fluorescence-aided Identification Technique (FIT) with those of the conventional diagnostic method regarding the identification of resin composite restorations. MATERIALS AND METHODS: Twenty examiners, 10 students, and 10 dentists were asked to identify composite restorations in a full-mouth model using both the FIT (405-nm light source) and the conventional method in combination with a common diagnostic light source. Each dental examination was repeated three times to calculate inter-/intra-operator agreement, repeatability, and reproducibility using kappa statistics. Predictive values were calculated using a filling prevalence of 42 % and the sensitivity and specificity of each method. Pearson's test and the 99 % confidence interval (CI) were used for comparison. RESULTS: The sensitivity (97 %, CI 94-99 %) and specificity (100 %, CI 98-100 %) of the FIT were significantly higher than those of the conventional method (27 %, CI 21-31 %, and 65 %, CI 58-72 %, respectively). Consequently, the positive (100 %) and negative (98 %) predictive values of the FIT were significantly higher than those of the conventional method (35 and 55 %, respectively). As expressed by the kappa statistics, the repeatability (0.96) and reproducibility (0.95) of the FIT were significantly better than those of the conventional method (0.49, CI 0.42-0.56, and 0.34, CI 0.26-0.43, respectively). CONCLUSION: Compared to the conventional technique, the FIT was significantly more reliable as shown by higher sensitivity, specificity, repeatability, and reproducibility values. CLINICAL RELEVANCE: The FIT should be considered as a reliable and practicable alternative in contrast to the conventional method, which was hardly sufficient as a diagnostic procedure.

In mixed biofilms Enterococcus faecalis benefits from a calcium hydroxide challenge and culturing.

AIM: To evaluate the fate of Enterococcus faecalis in dual-species and multispecies biofilms after treatment with calcium hydroxide (Ca(OH)2 ). METHODOLOGY: Biofilms were cultured from laboratory strains of E. faecalis and Pseudomonas aeruginosa, or from microbiota retrieved from primary root canal infections. The biofilms were then treated with Ca(OH)2 . The proportion of E. faecalis and P. aeruginosa and their susceptibility to disinfection were evaluated in a viability assay. In the mixed-species assay, the presence and proportions of E. faecalis before and after Ca(OH)2 treatment were evaluated with a quantitative polymerase chain reaction assay. Groups were compared using Mann-Whitney U-test and Student's t-tests. An α <0.05 was considered statistically significant. RESULTS: After Ca(OH)2 treatment in dual-species biofilms, the proportion of E. faecalis had increased (P < 0.001), whereas the total number of CFUs per biofilm was equal. Enterococcus faecalis was equally susceptible to disinfection by sodium hypochlorite (NaOCl) or by chlorhexidine. Pseudomonas aeruginosa had become more susceptible to NaOCl disinfection. The root canal isolates contained no detectable amounts of E. faecalis. After biofilm culturing or Ca(OH)2 treatment, it appeared that E. faecalis must have been present in 5 of 6 (83%) root canal samples. CONCLUSIONS: Calcium hydroxide favours the population of E. faecalis in a dual-species biofilm. Culturing multispecies root canal isolates makes E. faecalis detectable. E. faecalis was often present in primary endodontic infections, albeit in low numbers.

Guided endodontics: accuracy of a novel method for guided access cavity preparation and root canal location.

AIM: To present a novel method utilizing 3D printed templates to gain guided access to root canals and to evaluate its accuracy in vitro. METHODOLOGY: Sixty extracted human teeth were placed into six maxillary jaw models. Preoperative CBCT scans were matched with intra-oral scans using the coDiagnostix(™) software. Access cavities, sleeves and templates for guidance were virtually planned. Templates were produced by a 3D printer. After access cavity preparation by two operators, a postoperative CBCT scan was superimposed on the virtual planning. Accuracy was measured by calculating the deviation of planned and prepared cavities in three dimensions and angle. Ninety-five per cent confidence intervals were calculated for both operators. RESULTS: All root canals were accessible after cavity preparation with 'Guided Endodontics'. Deviations of planned and prepared access cavities were low with means ranging from 0.16 to 0.21 mm for different aspects at the base of the bur and 0.17-0.47 mm at the tip of the bur. Mean of angle deviation was 1.81°. Overlapping 95% confidence intervals revealed no significant difference between operators. CONCLUSION: 'Guided Endodontics' allowed an accurate access cavity preparation up to the apical third of the root utilizing printed templates for guidance. All root canals were accessible after preparation.

Accuracy of endodontic working length determination using cone beam computed tomography.

AIM: To evaluate the accuracy of endodontic working length (WL) measurements by cone beam computed tomography (CBCT). METHODOLOGY: Forty-two extracted human teeth were placed into three full jaw models. Preoperatively, CBCT scans of the models were performed (voxel size: 0.2 mm). Endodontic access cavities were prepared, and the coronal third of 70 root canals were pre-flared. The real WL was measured by inserting a K-file into the root canal until the tip was visible at the foramen, a silicon stopper was adjusted to the corresponding cusp tip, and the length was measured using a micrometer. CBCT WL was simply measured by tracing a line between the apical foramen and the corresponding cusp tip. When the foramen and cusp tip were not visible in one plane, the measurement was taken in two planes. To quantify measurement error, real and CBCT WLs were repeated four times by two experienced operators. Paired analysis for each variable was performed, and the mean of absolute differences and the corresponding 99% confidence intervals were calculated. The t-test was used for comparison. RESULTS: The coefficient of repeatability, reproducibility and interoperator agreement were <0.5 mm. CBCT measurements were accurate; the mean of absolute differences between CBCT and real WL was 0.41 mm (99% CI 0.31-0.52 mm). CONCLUSION: Using a simplified method, CBCT images of 0.2 mm voxel size can be used to accurately determine endodontic WL.

Predicting caries by measuring its activity using quantitative light-induced fluorescence in vivo: a 2-year caries increment analysis.

The aim of this study was to analyse the predictive power of several clinical baseline parameters and the de-/remineralisation properties of in vivo etched sites measured with quantitative light-induced fluorescence (QLF) for subsequent 2-year caries increment. At baseline, in 44 children (8.23 ± 1.5 years) two areas (diameter 2 mm) of the buccal surface of a primary posterior tooth were etched with 36% phosphoric acid gel for 1 and 4 min, respectively. The etched sites were analysed immediately after etching (ΔQ1) and 24 h (ΔQ2) later by QLF. Additionally, caries status (deft/DMFT and initial caries), approximal plaque, bleeding on probing, and the patient's current use of fluorides were recorded. In the 2-year follow-up, 29 children were re-assessed. After clinical examination, the caries increment was calculated (ΔDMFT) and correlated with the baseline clinical variables and the QLF readings. Results showed a significant positive correlation between ΔQ(1 min) and the ΔDMFT (r = 0.44, p = 0.02). The ΔDMFT was significantly correlated with the baseline deft (r = 0.56, p = 0.002), cavitated active caries lesions (r = 0.52, p = 0.003), and filled teeth (r = 0.53, p = 0.003). In a regression analysis the use of fluoridated salt (SC = -0.10) and fluoride gel (SC = -0.14) were negatively associated with ΔDMFT. In conclusion, these findings suggest that the demineralisation properties of the etched sites and the outcome of the 24-hour measurements with QLF are significantly associated with caries increment. Previous caries experience strongly correlated with caries increment in this group of children.