Assessment of the Root Canal Similarity in Contralateral Mandibular Incisors.

INTRODUCTION: The purpose of this study was to determine the degree of similarity between contralateral mandibular incisors utilising 3-dimensional (3D) models obtained from micro-computed tomographic (micro-CT) scans of extracted human teeth. The null hypothesis was that contralateral mandibular incisors do not exhibit matching symmetry. METHODS: Sixty pairs (n = 120) of extracted mandibular incisors were obtained from 30 patients and scanned with micro-CT with a voxel size of 15.0 µm. 3D virtual models of the pulpal cavities were rendered. Geometric morphometric deviation analysis was performed after mirroring, automatic alignment, and co-registration of the models of contralateral teeth root mean square (RMS) errors were calculated. The quantitative analysis of the 3D models included 6 different geometric parameters. Data sets were examined with a 2-sample Kolmogorov-Smirnov test. Post hoc retrospective power analysis was performed to find statistical power (α = 0.05). RESULTS: Contralateral pairs had a narrower distribution in deviation than random pairs. Also, contralateral pairs showed a statistically higher similarity coefficient (5 out of 6 geometric parameters) compared to random pairs (P < .001); no difference was found when comparing central to lateral pairs or between Vertucci type I configurations compared to non-type I. RMS errors had significantly lower Contralateral premolars (CPs) values than random pairs (P < .001). CONCLUSIONS: A high degree of similarity was demonstrated for pairing contralateral mandibular incisors using 3D models. The similarity between contralateral central and lateral incisors suggests that when screened and matched, these 4 teeth might be used in endodontic research where similar root canal anatomy is crucial.

Assessment of Teeth Prepared by Senior Dental Students for CAD/CAM Restorations.

The aim of this study was to evaluate teeth prepared for computer-aided design/computer-aided manufacturing (CAD/CAM) restorations by senior dental students using recently developed rubrics. The rubrics used evaluation criteria based on four factors: retention or resistance form; marginal or internal adaption or manufacturing process; biology, esthetics, or durability of restorative material; and intraoral scanner impression. In academic year 2018-19, four faculty members used the rubrics to assess 111 first maxillary right premolars (tooth no. 4) prepared for lithium disilicate crowns and 223 second maxillary right premolars (tooth no. 5) and first maxillary right molars (tooth no. 3) prepared for monolithic zirconia partial fixed dental prostheses. The preparations had been performed on typodont teeth. The most common errors identified for tooth preparations were in the finish line quality (136 errors in 223 prostheses), a criterion that is crucial for quality CAD/CAM restorations. To prevent poorly fit CAD/CAM restoration preparations that result from an unacceptable finish line quality, students need to understand the rationale used to develop detailed rubrics and adhere to the defined critera.

Comparison of Effectiveness of Two Teaching Methods on Acquisition of Skills in Preclinical Fixed Prosthodontics.

The aim of this study was to evaluate the effects of dental faculty-student interactions, virtual assessment software, and associated rubrics on student performance by assessing tooth preparations generated during the students' final practical exam. The study, conducted in 2017 and 2018, compared teeth prepared for preclinical fixed prosthodontics competency exams by two subsequent classes of second-year dental students trained using different methods. Class A was trained for nine months prior to the exam using feedback via student-faculty interactions and conventional rubrics. Class B was trained for five and half months prior to the exam via contemporary rubrics that incorporated feedback from both faculty and virtual assessment software. Two blinded, independent, and calibrated faculty members randomly evaluated the tooth preparations and graded them as excellent, standard, or standard not met for occlusal reduction, axial/lingual reduction, contour/long axis/axial wall height, finish line location, finish line quality, and finish of the preparation. The interrater agreement was slight to fair (0.01 < Kappa < 0.4) for evaluation of preparations. The teaching method did not have a significant impact (p>0.05) on student performance for the assessed criteria. These results suggest that, with the use of virtual assessment software, a course director may be able to shorten a course and obtain the same results as a nine-month course.