Evaluation of Convergence Angles in Posterior Crown Preparations by Dental Students at Zawia University

Abstract

Background and objectives: Achieving optimal axial taper and occlusal convergence in crown preparations is a crucial concern among dental students. Proper preparation design is essential for the long-term success of full-coverage restorations. This study aimed to evaluate the convergence angles and axial taper achieved by dental students in their crown preparations. Methods. A total of 80 posterior tooth preparations (40 mandibular first molars and 40 mandibular second molars) created by second-year dental students on a dental simulator were analyzed. The total occlusal convergence (TOC), bucco-lingual (BL) and mesio-distal (MD) convergence angles, as well as the degree of taper on the axial walls, were measured using the B&B dental software (Guide system, B&B, Italy). Statistical analysis was performed using SPSS version 27. Results. The overall mean of the total convergence angle was 21.88°, with a BL convergence angle mean value of 23.11° (standard deviation of 13.3°) and an MD convergence angle mean value of 20.66° (standard deviation of 11.0°). The results showed a statistically significant difference between the mesial axial taper and the distal axial taper (p-value < 0.001). However, no significant differences were observed between the buccal axial taper and lingual axial taper (p-value > 0.05), or between the BL convergence angle and MD convergence angle (p-value > 0.05). Conclusion. The study revealed variations in the convergence angles of full metal crown preparations created by dental students. The recommended convergence angle was difficult for these students to achieve.