AIM:This cross-sectional study aimed to compare the endodontic microbiome assessed from root canals of teeth associated with either symptomatic or asymptomatic apical periodontitis and analysed by 16S rDNA gene sequencing. METHODOLOGY:60 teeth presenting clinical and radiographic signs of symptomatic or asymptomatic apical periodontitis (n = 30) were included in this cross-sectional study after participants had given their written informed consent. After isolation with rubber dam, disinfection and access cavity preparation, glide paths were prepared using C-Pilot Files and K-Files under electronic root canal length control. Microbial samples were collected from a total of 120 root canals (symptomatic apical periodontitis, SAP: n = 62, asymptomatic apical periodontitis, AAP: n = 58) each with a sterile file (size 20/0.06) in a single length technique. Only one specimen per tooth was included in the analysis; in multi-rooted teeth, the specimen with highest sequencing depth. After DNA extraction, the hypervariable region V4 of the bacterial 16 S rRNA gene was amplified and sequenced (Illumina MiSeq). Taxonomy was assigned based on the expanded Human Oral Microbiome Database (eHOMD). Statistical analysis of diversity parameters comprised Mann-Whitney U tests and PERMANOVA. Compositional differences were evaluated by differential abundance analyses using DESeq2, LinDA, and ANCOM-BC2 methods. RESULTS:No differences were observed in richness and diversity (Shannon diversity index) on the genus or ASV level (p > 0.05). According to PERMANOVA, SAP and AAP microbiomes did not differ significantly both on genus and ASV levels (p > 0.05). Among highly abundant genera, Fusobacterium was indicated to be more abundant in SAP samples whereas Actinomyces was more abundant in AAP samples. CONCLUSIONS:The expression of clinical symptoms in apical periodontitis does not appear to be determined by specific microorganisms but may instead reflect shifts of the relative abundance of the microbial community.

OBJECTIVES:This meta-analysis compared hydraulic calcium silicate-based (HCSS) versus other types of root canal sealers regarding postoperative pain and treatment outcomes. DATA AND SOURCES:Five electronic databases were searched for randomized and non-randomized clinical studies from 1947 to 2026. Post-operative pain assessment was extracted as visual analogue scale scores (0-10). Treatment success and failure were recorded according to prespecified loose and strict radiographic criteria. For continuous and dichotomous outcomes, pooled effect estimates (e.g. standardized mean differences (SMD), odds ratios (OR)) with 95% confidence intervals (95%CI) were calculated using fixed- or random-effects models. STUDY SELECTION/RESULTS:Fifty-five articles were included, reporting on 53 cohorts comprising 5913 teeth at the end of the observation period. Forty studies investigated postoperative pain; 21 assessed treatment outcome using loose criteria and 14 strict criteria, with both reported in 12 studies. Sealer extrusion or resorption was documented for 25 cohorts. Patients treated with HCSS reported slightly lower postoperative pain scores after 6 hours (OR=-0.27, 95%CI:-0.51--0.04, moderate level of evidence), although this tendency was inconsistent over different postoperative intervals. For treatment success defined according to loose criteria, use of HCSS resulted in significantly fewer failures than other types of sealers (OR=0.70, 95%CI:0.50-0.99,high level of evidence), whereas no significant difference between sealer types was observed when strict criteria were applied (OR=0.89, 95%CI:0.67-1.19, high level of evidence). CONCLUSION:HCSS represent a clinically validated sealer group with no increased risk of elevated postoperative pain and can contribute to successful root canal treatment, with success rates comparable to those of other types of sealers. CLINICAL SIGNIFICANCE:Hydraulic calcium silicate-based root canal sealers were promoted for their biocompatibility and bioactivity. The results of clinical trials show that HCSS perform similar to other types of root canal sealers in terms of postoperative pain and treatment outcomes and display a well-investigated alternative to epoxy resin or zinc oxide eugenol sealers. REGISTRATION:PROSPERO database CRD420261365434.

This multinational cone-beam computed tomography (CBCT) study evaluated the root canal morphology of mandibular first premolars (M1Ps) from 21 countries and compared how well the Ahmed and Vertucci classification systems represented these patterns. A total of bilateral mandibular first premolars from eligible CBCT scans were assessed using both systems, and the data were analyzed with a hierarchical probabilistic approach to account for population and imaging-related variation. Across the overall dataset, a simple single-canal configuration was the dominant pattern, and this remained the most common finding in all populations despite limited but structured variation in less frequent subclasses. The Ahmed system classified all observed configurations, whereas the Vertucci system left approximately 10.2% of cases without an equivalent category. In addition, Ahmed preserved more anatomical detail, while Vertucci compressed several distinct configurations into broader groups. Demographic and imaging-related factors had modest effects, with voxel size showing the clearest technical influence on the detection of more complex patterns. Overall, M1P morphology showed a stable global pattern with secondary heterogeneity, and the Ahmed system provided a more complete and informative representation for CBCT-based morphology assessment across diverse populations.

AIM:Appropriate antibiotic prescribing is a core competency in dental education. This study evaluated dental students' knowledge, antibiotic selection patterns, and adherence to international guidelines for the management of endodontic infections. MATERIALS AND METHODS:An online survey was administered to students in their final two clinical years across 19 countries. Three clinical scenarios were evaluated: first-line antibiotic choice, second-line when the first choice is ineffective, and drug of choice for penicillin-allergic patients. Participants reported drug, dose, frequency, and duration. Guideline adherence was quantified using a 0-5 scoring system based on European Society of Endodontology and American Association of Endodontists recommendations. Mixed-effects linear regression models with country as a random effect were used to identify predictors of guideline-concordant prescribing. RESULTS:A total of 4226 responses were analysed. Amoxicillin was the most frequently selected first-line antibiotic (57.6%), followed by amoxicillin-clavulanic acid (18.4%), with marked between-country variation; adjusted first-choice concordance was highest in Colombia (4.57) and lowest in Bangladesh (2.49). For second-line therapy, amoxicillin-clavulanic acid predominated (33.2%), with the highest adherence in Ecuador (3.40) and the lowest in Switzerland (2.15). In penicillin-allergic patients, clindamycin was most commonly selected (47.8%), but allergy-specific concordance varied widely, ranging from 3.52 in Colombia to 1.06 in India. Age positively predicted second-line concordance, while lower allergy-specific concordance was observed among second-year students and males. CONCLUSIONS:Marked variability and frequent deviations from guideline-recommended prescribing highlight persistent educational gaps. Strengthening antimicrobial stewardship training within undergraduate dental curricula is warranted.

INTRODUCTION:3D-printed teeth/models are important adjuncts in dental education. Nevertheless, there is a lack of simulated cases to learn and understand complex treatment scenarios, including anamnesis, diagnosis, treatment planning and therapy. MATERIAL AND METHODS:Third-year students (n = 44) received a complete 3D-printed model (upper and lower jaw) of a patient who needed emergency treatment. Based on the information provided (i) general history, (ii) specific dental history, (iii) radiographs, the students made a diagnosis and planned the treatment, which they performed independently under supervision. The case included periodontal, restorative, endodontic and surgical treatments and semi-permanent splinting. Using a 3- or 5-point Likert scale, students rated each treatment episode, the learning outcome and the impact of the model on training using a questionnaire. Chi-square test served for statistical analysis. RESULTS:The majority (63.6%) stated that the interdisciplinary model allowed a better learning effect than the approach dealing with each section separately (p < 0.05). Almost all students rated the diagnostic process as excellent (88.0%-95.5%), as the general history, dental history and radiographs were consistent with the clinical findings. Periodontal therapy was rated significantly lower compared to all other areas (p < 0.05). For endodontic treatment, the students disagreed, abstaining from practising on extracted human teeth. However, the students felt confident to perform all treatment steps in the following clinical courses. CONCLUSION:Customised, interdisciplinary 3D-printed teaching models covering complex treatment strategies were best suited to enhance dental students' skills and foster their enthusiasm for the integrated diagnosis and treatment planning process. Their implementation into dental education is strongly recommended to improve both training and future patient care.

This study aimed to evaluate the root and root canal morphology of maxillary first premolars (M1Ps) globally using cone-beam computed tomography (CBCT), comparing results with Vertucci's and Ahmed et al.'s classification systems. CBCT images were obtained for various purposes such as orthodontic treatment planning, tooth impaction, implant surgery, and trauma cases. M1Ps were evaluated in three planes to determine root and root canal morphology, and root bifurcation levels were assessed using integrated software. Prevalence variations between countries and overall prevalence were analyzed using meta-analysis software. A total of 6,600 patients (13,200 bilateral M1Ps) were examined. According to Vertucci's classification, Type IV (59%), Type II (12%), Type I (9%), and Type III (8%) were the most common configurations. Based on Ahmed's classification,2MP B1 P1 was the most prevalent configuration (53%), followed by 1MP1 (9%),1MP1-2-1 (8%), and 1MP2-1-1 (7%). The prevalence of 2MP B1 P1 by gender revealed a pooled prevalence of 58% in males and 50% in females. No significant difference was found across age ranges (p > 0.05). Ahmed's classification system provided a more comprehensive analysis by successfully classifying all cases, whereas Vertucci's system failed to categorize 1.8-2.7% of the cases. Significant bilateral symmetry in root morphology was noted. There are regional and gender-specific differences in the root canal morphology of M1Ps. Ahmed et al.'s classification system was more comprehensive, effectively categorizing all observed morphologies compared to Vertucci's system, which had limitations and left some morphologies unclassified.

INTRODUCTION:This study aimed to evaluate screw-in force and torsional load generated by 6 fully rotating nickel-titanium (NiTi) file systems with different geometry, cross-section, and rotational speed. METHODS:Ninety mesial roots of human lower molars were divided into 6 groups according to the file system used for canal preparation: F360, F6, TruNatomy, RACE EVO, JIZAI I, and JIZAI II. Groups were standardized balanced to working length, chord length, and canal curvature. A custom-built test rig with an attached endodontic motor (Schlumbohm EndoPilot 2) and a 6-axis measuring device were used to measure the apically directed, screw-in and torque forces generated along the axis of the tooth as the NiTi file was moved with an amplitude of 3 mm at each peck, increasing penetration depth by 2 mm at each peck. The rotary speed was set individually for each file according to the manufacturer's instructions. Two sets of 3 pecking motions were performed with intermitting cleanings of the file and needle irrigation of the root canal. Additionally, torque forces were recorded by the endodontic motor. Maximum force values for each set of pecks were analyzed using the Kruskal-Wallis test. The correlation between z-axis tooth torque and motor-measured torque was assessed using Spearman's correlation. RESULTS:Significant differences existed between the files regarding apically directed, screw-in and torque forces (P < .05). Torque values generated on the tooth along the z-axis and torque on the file correlated significantly (P < .001). CONCLUSIONS:Radial lands or alternating cutting edges affect screw-in effect and torsional load of NiTi files.

Aims Composite materials are widely used in dentistry for direct tooth restorations. However, they are highly sensitive to the working technique employed during the restorative procedure. Even minor procedural errors can have a significant impact on the quality including the longevity of the restoration. Hence the aim of this study was to determine the material preferences and analyse the clinical problems associated with direct composite restorations in a cohort of dentists. Methods A 20-item online questionnaire was created in English and administered 1830 general dentists and specialists in 13 countries. The first section of the questionnaire included four questions to elicit demographic data, and the second section comprised 16 questions focused on material preferences for conservative restorations, durability of composite restorations, and the most challenging stages the dentists faced during the composite restorative procedures. Results Respondents decided most often to use composite materials for the tooth restorations (OR 997.4, 95% CI 233.8-4254.8, P value <.001). Most respondents indicated that the durability of composite restorations was approximately 7 to 10 years (41.5%). Among the factors affecting durability, maintenance of a dry cavity was the most often reported reason (47.1%) and the foremost challenge faced by dentists (61.0%) during the composite restorative procedures. Conclusions Our study confirmed that resin-based composites are the most popular material for direct restoration in many countries. Although working with this material is difficult and involves multiple steps, maintaining a dry cavity during bonding, and material application may affect the therapeutic success and durability of these restorations. Clinicians need to be attentive to this issue and be prepared to adapt their decision-making and consider opting for alternative restorative materials, if appropriate.

AIM:To develop and evaluate an e-learning tool utilizing a generative pre-trained transformer (GPT), a form of artificial intelligence (AI), to allow for realistic conversation on virtual patients when undergoing training on how to diagnose diseases of endodontic origin, and to evaluate improvements in self-perceived skills. METHODOLOGY:A web app consisting of three components [website for user access, database server with patient case information, GPT-4-turbo model (OpenAI)] was designed to serve as the e-learning platform. Undergraduate students from 4th and 5th year at the dental school of the University of Münster, Germany, were asked to solve eight cases of virtual patients presenting with pain from endodontic or periodontal origin. Before, a questionnaire applying a 5-point Likert scale served to evaluate the current self-perceived state regarding the education, experience and skills in endodontic diagnostics and emergency treatment. After a 3-month timeframe of working with the programme individually, the students were asked to answer a second questionnaire which focused on their experience and self-perceived skills improvement after using the training software. RESULTS:Ninety-two students participated in the first questionnaire and 72 students finished the second questionnaire, resulting in a drop-out rate of 21.7%. Students in the 5th-year reported more experience in dealing with emergency patients. Initially, both cohorts mainly did not feel confident to perform endodontic diagnostics independently. The evaluation of confidence to perform endodontic diagnostics independently, both by 4th- and 5th-year students, seemed improved after the training on the e-learning tool. The tool was recommended to be available for endodontic education by 72.2% of the students, who strongly agreed to such a statement. 76.4% of the participants strongly agreed to recommend the use of the tool to other students. CONCLUSIONS:AI-based interactive e-learning programmes allowing for complex conversational patient encounters present a possibility to improve diagnostic and interactive skills of undergraduate students.

Introduction: The aim was to evaluate the suitability of paper points or endodontic nickel- titanium files to sample microorganisms for in vivo investigation of endodontic microbiota by 16S ribosomal DNA (rDNA) sequencing. Methods: Forty-five patients presenting clinical and radiological signs of apical periodontitis were recruited for sampling, giving their written informed consent. Glide paths were assessed using C-Pilot Files and K-Files under electronic root canal length control under aseptic conditions. Microbial samples were taken from 84 root canals in duplicate, the first sample with a sterile paper point (size 15), the second with a sterile file (size 20/.06). After DNA extraction, the hypervariable region V4 of the bacterial 16S rRNA gene was amplified and sequenced (Illumina MiSeq). Sequencing data were trimmed with Cutadapt and exact amplicon sequence variants generated by DADA2. Taxonomy was assigned based on the Human Oral Microbiome Database (eHOMD). Statistical analysis of diversity parameters comprised Wilcoxon signed-rank tests and permutational analysis of variance (PERMANOVA). Compositional differences were evaluated by differential abundance analysis (DESeq2). Microbial contamination during the sampling process and analysis were evaluated. Results: Concerning alpha diversity, richness and dissimilarity differed nonsignificantly between paper point and instrument samples (P> .05), whereas a significant difference was observed in the Shannon index (P < .05). Regarding beta diversity, paper point and instrument samples presented with similar microbial community compositions (P 5 1.0, PERMANOVA). Paper point controls contained significantly higher proportions of Pseudomonadales (P < .05). Conclusions: Paper point and endodontic instrument sampling generate valid specimens for 16S rDNA community profiling. Endodontic instrument sampling is easier to execute and, therefore, could be the technique of choice. (J Endod 2025;51:164-171.)

Introduction: This study aimed to evaluate the removal of a bio film-mimicking hydrogel from isthmus structures in a simulated complex root canal system consisting of 2 curved root canals by Laser-activated irrigation (LAI, AdvErl Evo, Morita) and mechanical activation techniques. Methods: A 3D-printed root canal model with 2 parallel root canals (60 degrees - curvature, radius 5 mm, dimension 25/.06) with a total length of 20 mm connected via isthmuses (2.5 ! 0.4 ! 0.2 mm) at 5 mm and 8 mm from the apical endpoint and with lateral canals (diameter 0.2 mm) in all directions at 2, 5, and 8 mm from the apex was filled with a colored bio film-mimicking hydrogel. Irrigation protocols under continuous irrigation with distilled water (3 ! 20s per root canal; 3 ml/20s; n = 20) included conventional needle irrigation ( = NI); manual agitation ( = MA, gutta-percha point 25/.06); EndoActivator ( = SAI-EA, 25/.04); EDDY ( = SAI-E, 25/.04); ultrasonically-activated irrigation ( = UAI) and LAI (Er:YAGlaser; P400FL tip at canal entrance; 25pps, 50 mJ, 300 ms). Removal of the hydrogel was determined as a percentage via standardized photos through a microscope. Statistical analysis was performed using Kruskal -Wallis and Conover tests ( P = .05). Results: Laseractivated irrigation (LAI) was associated with the greatest removal of hydrogel from the entire root canal system ( P < .05), followed by SAI-E. No signi ficant differences were reported for the coronal isthmus between LAI, SAI-E, NI, and MA ( P > .05), but inferior results for SAI-EA and UAI ( P < .05). In the apical isthmus, all techniques outperformed UAI ( P < .05), with LAI, SAI-E, and NI showing the best results ( P < .05). Conclusions: Laser-activated irrigation (LAI) was superior to other irrigation techniques in the entire root canal system. SAI-E and NI performed comparable to LAI in the isthmuses.

ObjectivesResin-based composites (RBCs) evolved into favoured materials for teeth restorations, marking a significant change in dental practice. Despite many advantages, RBCs exhibit various limitations in their physical and chemical properties. Therefore, we assessed the dentists' awareness of possible complications after direct composite restorations and their opinions about this material.MethodsThe online questionnaire was created in English in May 2023. A 16-item survey was dedicated to general dentists and specialists. The first section included four questions related to demographic characteristics. The second section comprised twelve questions and focused on awareness of potential side effects of composite restorations, the most crucial advantages and disadvantages of composite resins, and the frequency of experienced clinical complications after the application of composite materials.ResultsA total of 1830 dentists from 13 countries took part in the survey. Dentists most often declared awareness of low adhesion to the dentine (77.5%) and, most rarely, solubility in oral fluids (42.6%). Aesthetics was identified as the main advantage of composite fillings (79%), followed by the possibility of repair (59%) and adhesion to enamel (57%). Polymerisation shrinkage was a major disadvantage for most countries (70% overall). Analysing the declared potential clinical complications for all countries, statistically significant findings were obtained for marginal discolouration (OR=2.982, 95%CI:1.321-6.730, p-value=0.009) and borderline significance for secondary caries (OR=1.814, 95%CI:0.964-3.415, p-value=0.065).ConclusionsDentists value aesthetics and repairability but are aware of shrinkage and experience discolouration. The issue of toxicity and solubility seems to be the least known to dentists.Clinical significance: Dentists should use RBCs with critical caution due to possible side effects. Despite the undoubted aesthetics of direct composite restorations, it is necessary to remember potential clinical complications such as marginal discolouration or secondary caries.

Reciprocating motion expands the lifetime of endodontic instruments during the preparation of severely curved root canals. This study aimed to investigate the time to fracture (TTF) and number of cycles to failure (NCF) of different reciprocating instruments (n = 20 in each group) at body temperature using a dynamic testing model (amplitude = 3 mm). Reciproc Blue (RPB), size 25/.08, WaveOne Gold (WOG) 25/.07, Procodile (Proc) 25/.06, R-Motion (RM_06) 25/.06 and R-Motion (RM_04) 30/.04 instruments were tested in their specific reciprocating motion in artificial matching root canals (size of the instrument ± 0.02 mm; angle of curvature 60°, radius 5.0 mm, and centre of curvature 5.0 mm from apical endpoint). The number of fractured instruments, TTF, NCF, the and lengths of the fractured instruments were recorded and statistically analysed using the Chi-Square or Kruskal–Wallis test. Both TTF (median 720, 643, 562, 406, 254 s) and the NCF (3600, 3215, 2810, 2032, 1482 cycles) decreased in the following order RM_06 > RPB > RM_04 > Proc > WOG with partially significant differences. During testing, only six RM_06 instruments fractured, whereas 16/20 (RPB), 18/20 (Proc), and 20/20 (RM_04, WOG) fractures were recorded (p < 0.05). Within the limitations of the present study, blue-coloured RPB and RM instruments exhibited a significantly superior cyclic fatigue resistance compared to SE-NiTi and Gold-wire instruments. Heat treatment, cross-sectional design and core mass significantly influenced the longevity of reciprocating instruments in cyclic dynamic testing.

AIM:To investigate the influence of pulse energy, tip geometry and tip position in simulated 3D-printed root canals with multiple side canals at different levels in all directions on the cleaning performance of laser-activated irrigation (LAI) compared to sonic activation (EDDY) and conventional needle irrigation (NI). METHODOLOGY:3D-printed root canal models (25/.06, length 20 mm, curvature 60°, radius 5 mm) with side canals (diameter 0.2 mm) at 2, 5 and 8 mm from the apex were filled with coloured biofilm-mimicking hydrogel. LAI (Morita AdvErL Evo, Kyoto, Japan) was performed with six settings (n = 20; pulse-energy, pulses per second [PPS], tip position): LAI1 (50 mJ, 25 PPS, P400FL, canal entrance [CE]), LAI2 (same as LAI1, but insertion depth 9 mm before the apical endpoint [AE] [corresponding to 1 mm above the first lateral canals]), LAI3 (80 mJ, 25 PPS, P400FL, 9 mm before AE), LAI4 (same as LAI 3, but at CE) for 3 × 20 s each, LAI5 (50 mJ, 25 PPS, P400FL 2 × 20 s, CE & R200T (30 mJ, 25 PPS, 1 × 20 s, 9 mm before AE), LAI6 (30 mJ, 25 PPS, R200T, 9 mm before AE, 3 × 20 s). A continuous irrigation (3 mL/20 s) using distilled water accompanied the irrigation cycles. NI and EDDY (3 × 20 s each; 3 mL/20 s irrigation, insertion AE minus 1 mm, amplitude 4 mm) served as control groups. Biofilm-mimicking hydrogel removal (ImageJ, NIH) was assessed for the entire system, the central canal and the lateral canals using standardized photographs with a microscope (Expert DN, Müller-Optronic) and statistically analysed was performed using Kruskal-Wallis and Dunn tests (p = .05). Irrigant extrusion beyond the foramina was also recorded. RESULTS:LAI2 (99.08%; interquartile range [IQR]: 96.85-100.00) and LAI3 (97.50%; 96.24-100.00) achieved the significantly best and LAI6 (80.08%; 73.41-84.69) the significantly worst removal of hydrogel from the entire root canal system amongst all LAI configurations (p < .05). There were no significant differences between LAI6, EDDY (72.89%; 67.49-76.22) and manual irrigation (54.39%; 51.01-56.94) (p > .05). R200T laser tip caused significantly more often irrigant extrusion than all other techniques (p < .05). CONCLUSION:Tip design, energy settings, and the positioning of the laser tip below the canal entrance caused an improvement in cleaning performance of the LAI. However, the small R200T tip created significantly more procedural errors (irrigant extrusion) due to higher concentrated energy.

Undergraduate students often lack experience in diagnosing dental pain, especially in those cases with pulpal involvement and a need for endodontic treatment. Not all university dental clinics provide participation of the students in providing emergency dental services. During their undergraduate dental education, the students have to be provided with clinical teaching and support how to diagnose and prepare treatment plans for emergency and/or elective dental treatment. Thus, after graduation young dentists would not face challenges in diagnosing the location and cause of the odontogenic pain. Developing an e-learning tool utilizing the Generative Pre-trained Transformer 4 (GPT-4) Model (OpenAI) is to enable students to undergo a proper training on how to diagnose diseases of endodontic origin in realistic conversational setting on virtual patients. Unlike previous linear conversational approaches,1 the GPT-4 model allows for advanced, life-like conversations. International Nursing Association for Clinical Simulation and Learning standards of best practice simulation design were applied.2 Students receive a briefing within the e-learning tool including an introduction to the setting, a program overview, and a guide for a structured diagnostic approach. Afterward, they will engage in diagnosing a virtual patient. Students are required to conduct the diagnostic process, fostering a profound immersion in the topic and thereby cultivating the development of a structured personal approach of diagnosing the cause of dental pain. They will have the opportunity to work simultaneously on their communicative skills. To achieve the necessary realism, each case provides a patient's history and all essential parameters required for a final diagnosis. These include pain history, medical history, clinical presentation, clinical tests, and radiographic findings (Figures 1 and 2). This proposed approach also presents the opportunity for students to learn how to educate their patients on their condition and the proposed treatment plan in order to obtain informed consent for dental treatment. This prompts the student to apply their theoretical knowledge in a reality-based setting and critically examine their own potential knowledge gaps (Figure 3). The completed conversation with the patient is followed by a debriefing, providing information on the correct diagnosis and an exemplary annotated chat protocol conducted by an experienced clinician. In this way, observational learning is facilitated and enhanced in relation to the students’ structured diagnostic and communication approach. The preliminary pilot testing with a selected group of students and teachers has yielded promising results, suggesting this method as a viable means of practicing diagnostic skills in a secure environment. However, the significant effort required to construct patient cases cannot be understated, particularly due to the difficulty in obtaining clinical images and radiographs because of copyright restrictions. Furthermore, careful planning and iterative refining were necessary to obtain reliable outputs from the artificial intelligence model. To mitigate the unwanted behavioral characteristics of GPT models, such as hallucinations, a detailed and comprehensive case design was needed, along with restrictive guidelines for the GPT model. Thus, the model was confined to answer only database-solvable queries and otherwise it would have responded only in an evasive manner. A future pilot study is planned with a more extensive group of undergraduate students to appraise the effectiveness of this program. The objective is to gather additional insights into how it is perceived by a larger student population, which will later help identify areas for further enhancements. The authors have nothing to report. Open access funding enabled and organized by Projekt DEAL. The authors declare they have no conflicts of interest.

To investigate the influence of pulse energy, tip geometry and tip position in simulated 3D-printed root canals with multiple side canals at different levels in all directions on the cleaning performance of laser-activated irrigation (LAI) compared to sonic activation (EDDY) and conventional needle irrigation (NI). 3D-printed root canal models (25/.06, length 20 mm, curvature 60°, radius 5 mm) with side canals (diameter 0.2 mm) at 2, 5 and 8 mm from the apex were filled with coloured biofilm-mimicking hydrogel. LAI (Morita AdvErL Evo, Kyoto, Japan) was performed with six settings ( n = 20; pulse-energy, pulses per second [PPS], tip position): LAI1 (50 mJ, 25 PPS, P400FL, canal entrance [CE]), LAI2 (same as LAI1, but insertion depth 9 mm before the apical endpoint [AE] [corresponding to 1 mm above the first lateral canals]), LAI3 (80 mJ, 25 PPS, P400FL, 9 mm before AE), LAI4 (same as LAI 3, but at CE) for 3 × 20 s each, LAI5 (50 mJ, 25 PPS, P400FL 2 × 20 s, CE & R200T (30 mJ, 25 PPS, 1 × 20 s, 9 mm before AE), LAI6 (30 mJ, 25 PPS, R200T, 9 mm before AE, 3 × 20 s). A continuous irrigation (3 mL/20 s) using distilled water accompanied the irrigation cycles. NI and EDDY (3 × 20 s each; 3 mL/20 s irrigation, insertion AE minus 1 mm, amplitude 4 mm) served as control groups. Biofilm-mimicking hydrogel removal (ImageJ, NIH) was assessed for the entire system, the central canal and the lateral canals using standardized photographs with a microscope (Expert DN, Müller-Optronic) and statistically analysed was performed using Kruskal–Wallis and Dunn tests ( p = .05). Irrigant extrusion beyond the foramina was also recorded. LAI2 (99.08%; interquartile range [IQR]: 96.85–100.00) and LAI3 (97.50%; 96.24–100.00) achieved the significantly best and LAI6 (80.08%; 73.41–84.69) the significantly worst removal of hydrogel from the entire root canal system amongst all LAI configurations ( p < .05). There were no significant differences between LAI6, EDDY (72.89%; 67.49–76.22) and manual irrigation (54.39%; 51.01–56.94) ( p > .05). R200T laser tip caused significantly more often irrigant extrusion than all other techniques ( p < .05). Tip design, energy settings, and the positioning of the laser tip below the canal entrance caused an improvement in cleaning performance of the LAI. However, the small R200T tip created significantly more procedural errors (irrigant extrusion) due to higher concentrated energy.

Introduction: To compare the biofilm-mimicking hydrogel removal efficiency of laser-activated irrigation (LAI) with five other irrigation techniques in simulated curved root canals with lateral canals. Methods: Three-dimensional-printed root canal models (60 degrees-curvature, radius 5 mm; dimension 25/.06) with a total length of 20 mm and lateral canals in all directions at 2, 5, and 8mm(diameter 0.2 mm) from the apex were filled with a colored biofilm-mimicking hydrogel. The following protocols (each 3 x 20 seconds continuous irrigation with distilled water 3 ml/20 seconds; n 5 20) were carried out: conventional needle irrigation; manual agitation ([MA], gutta-percha point 25/.06); EndoActivator (=sonically-activated irrigation EndoActivator, 25/.04); EDDY (5sonically-activated irrigation EDDY [SAI-E]; 25/.04); ultrasonically-activated irrigation and LAI (Erbium-doped Yttrium Aluminum Garnet laser; P400FL tip at canal entrance; 25 pps, 50 mJ, 300 ms). Standardized photos were taken with a microscope and the removal of the hydrogel was determined as a percentage for the entire system, the main canal and the lateral canals. Statistical analysis was performed using analysis of variance and Scheffe test (P 5.05). Results: LAI (89.3% +/- 5.9%) showed the greatest hydrogel removal followed by SAI-E (65.5% +/- 3.3%) and ultrasonically-activated irrigation (59.1% +/- 4.7%), with significant differences between these groups (P < .05). Needle irrigation, MA, and sonically-activated irrigation EndoActivator performed equally (P > .05) and obtained the significantly lowest values (P < .05). LAI and SAI-E showed the significantly best hydrogel removal from the main canal (P < .05). At all three levels, LAI removed significantly more hydrogel from the lateral canals than all other techniques (P,.05). Conclusions: LAI was superior to other techniques in both the entire systemand the lateral canals in removing the hydrogel. SAI-E achieved comparable results in the main canal.

Background: An additional canal found in the mandibular first molar (M1M) is the middle mesial canal (MMC), which is often missed during root canal treatment. In this study, the prevalence of MMC in M1M on cone-beam computed tomography (CBCT) images was evaluated in 15 countries, along with the effect of some demographic factors on its preva-lence. Methods: Deidentified CBCT images were scanned retrospectively, and the ones including bilateral M1Ms were included in the study. A written and video instruction program explaining the protocol to be followed step-by-step was provided to all observers to calibrate them. The CBCT imaging screening procedure consisted of evaluating three planes (coronal, sagittal, and axial) after a 3-dimensional alignment of the long axis of the root(s). The presence of an MMC in M1Ms (yes/no) was identified and recorded. Results: In total, 6304 CBCTs, representing 12,608 M1Ms, were evaluated. A significant difference was found between countries (P < .05). MMC prevalence ranged from 1% to 23%, and the overall prevalence was 7% (95% confidence interval [CI]: 5%-9%). No significant differences were found between the left and right M1M (odds ratio = 1.09, 95% CI: 0.93, 1.27; P > .05) or between genders (odds ratio= 1.07, 95% CI: 0.91, 1.27; P > .05). As for the age groups, no significant differences were found (P > .05). Conclusions: The prevalence of MMC varies by ethnicity, but it is generally estimated at 7% worldwide. Physicians must pay close attention to the presence of MMC in M1M, especially for opposite M1Ms, due to the prevalence of MMC being significantly bilateral. (J Endod 2023;49:549-558.)

Die Wurzelkanalfüllung hat das Ziel, die durch die chemomechanische Bearbeitung des Wurzelkanalsystems erreichte Freiheit oder Reduktion von Mikroorganismen langfristig zu sichern und das Wurzelkanalsystem nach apikal und koronal abzudichten. Zu diesem Zweck wurden in den vergangenen Jahrzehnten immer wieder neue Materialien und Techniken vorgestellt, von denen sich viele klinisch bewährt haben. Im vorliegenden Artikel werden aktuelle Entwicklungen und etablierte Materialien aus dem Bereich der Wurzelkanalfüllung vorgestellt. Insbesondere kalziumsilikatbasierte Sealer, die oftmals als Biokeramiken beworben werden, stellen klassische Konzepte wie kalt-laterale oder warm-vertikale Kompaktion infrage und rücken die Single-Cone-Wurzelkanalfüllung wieder in den Fokus. Aufgrund der Entwicklung dieser neuen Materialien bedarf es einer Anpassung des gesamten Behandlungskonzepts.