Introduction: There are currently no established guidelines to determine which cases general practitioners should refer to an endodontist for root canal treatment. The American Association of Endodontists (AAE) has developed the EndoCase mobile application (ECA), which utilizes either a full or abridged rubric to assign case difficulty level and provide referral guidelines to general practitioners and dental students. Objective: The objective of this study was to determine whether the abridged criteria of the EndoCase application can help predict the incidence of procedural errors in nonsurgical root canal treatment of mandibular molars in an undergraduate dental clinic based on the difficulty level. Methods: A list of patients who received primary root canal treatment on mandibular first molars in the undergraduate dental clinic from 2015-2020 was obtained. Ninety patients qualified for inclusion. Case difficulty level was assessed using the ECA by three providers with differing levels of experience. Incidence of procedural errors was determined from post-operative radiographs by two calibrated independent observers. Results: The most common endodontic mishaps were errors during access cavity preparation followed by the presence of voids in the root filling, with an incidence of 54.4% and 45.6%, respectively. There were no significant differences regarding case difficulty level and the incidence of total procedural errors nor number of treatment visits. Of the individual error types, the presence of obturation >2mm short of the radiographic apex was weakly correlated with case difficulty level (r = 0.226, pConclusion: There is minimal correlation between the difficulty level of mandibular molars determined by the ECA and the number of treatment visits or overall incidence of procedural errors.

Aims Use of 3D printed models in Endodontics has been gaining popularity since the technology to create them became more affordable. Currently, there are no studies that evaluate the influence of 3D models on endodontic surgical treatment planning and on operator confidence. Therefore, aims of this study were to: (i) Determine whether the availability of a 3D printed analogue can influence treatment-planning and operator confidence; and, (ii) Assess which factors of operator confidence are influenced, if any. Materials and Methods Endodontists were asked to analyze a pre-selected CBCT scan of an endodontic surgical case and to answer a questionnaire that determined their surgical approach for that case. After 30 days, the same participants were asked to analyze again the same CBCT scan. This time however, a 3D printed model of the scan was made available to the participants and to perform a mock osteotomy on the model. The participants were then asked to respond to the same questionnaire that they responded to 30 days prior to determine if there would be any changes to their treatment plan. A new set of questions were added to the survey to evaluate the influence of the 3D printed model on participants’ confidence in performing endodontic surgery. The responses were statistically analyzed using Chi square test followed by either logistic or ordered regression analysis while adjusting for experience of participant. Adjustment for multiple comparison analysis was done using Bonferroni correction. Statistical significance was set at £0.005. Results Availability of the 3D printed model and the CBCT scan together resulted in statistically significant differences in the participants’ responses to their ability to clearly detect bone landmarks, accurately predict the location of osteotomy, and in determining the following: size of osteotomy, angle of instrumentation, involvement of critical structures in flap reflection and involvement of vital structures during curettage. In addition, the participants’ confidence in performing surgery was significantly higher versus having CBCT scans alone. There were no statistically significant changes with decisions on flap design and extent, visualizing critical structures, lesion size, injury to vital structures during osteotomy, the length of root that could be resected and the number of roots involved. Conclusions The availability of 3D printed models did not alter the participants’ surgical approach, but it significantly improved their confidence for endodontic microsurgery, which can be attributed to better visualization of anatomical structures.