Convergence angles of metal ceramic crowns prepared by dental students

Abstract

Convergence angles of crown preparations achieved by dental students vary from the recommended angles and depend on many variables and factors. Sex of operators and examination conditions in which preparations were made have not been reported in the literature. The purpose of this study was to determine the mean convergence angles produced by fifth-year dental students at King Abdulaziz University. Maxillary first premolar abutment preparations for metal ceramic restoration were made by fifth-year dental students on typodonts under preclinical examination conditions. A total of 68 preparations, made by 38 male and 30 female students, were randomly selected for evaluation of the buccolingual and mesiodistal convergence angles of each abutment tooth with an optical preparation scanner and digitizer to produce 3-dimensional digital objects. Two-sided t tests were performed to compare the buccolingual and mesiodistal angles between the sexes. The mean mesiodistal angle of all preparations was 11.11 ±4.79 degrees, and the mean buccolingual angle was 10.49 ±3.95 degrees. The mean buccolingual angle in preparations by male students was 10.16 ±3.90 degrees, compared with 11.46 ±5.06 degrees in preparations by female students. The mean mesiodistal angle was 10.92 ±4.03 degrees in preparations by male students, compared to 10.66 ±4.45 degrees in preparations by female students. No statistical difference was observed between the sexes for either angle (buccolingual, P=.435; mesiodistal, P=.497). The smallest andlargest angles observed were 2.59 and 24.64 degrees. Approximately 12% of male students and 10% of female students made preparations with less than a 6-degree (ideal convergence angle) buccolingual or mesiodistal angle. The average convergence angles produced were between 10.16 and 11.46 degrees. Several students were able to achieve ideal convergence angles. Male and female students achieved similar buccolingual and mesiodistal convergence angles.