Influence of Operator Experience on Clinically Achieved Convergence Angle of Tooth Preparations for Metal-Ceramic Crowns

Abstract

Objective: To compare clinically achieved convergence angle values of teeth prepared by operators having different experience levels and relate them with recommended values.
 Study Design: Cross-sectional analytical study.
 Place and Duration of Study: Department of Prosthodontics, Islamic International Dental Hospital, Islamabad Pakistan, from Dec 2018 to May 2019.
 Methodology: A total of 100 crown dies of molars prepared by House Officers (Group-I) and Postgraduate Residents (Group-II) of the Prosthodontics department were collected retrospectively. Auto CAD 2007 software was used for the measurement of convergence angle. One sample t-test was applied to compare the mean convergence angle values with theoretical values. In addition, independent samples t-test was applied to compare convergence angle values among Clinician Groups with different experience levels.
 Results: Significant difference (p <0.001) was found between the tooth preparations performed by both study Groups. Greater convergence angles were achieved by operators having lesser experience, i.e., Group-I (House Officers) in contrast to Group-II (Post-graduate Residents). The convergence angle achieved by both study groups was far greater than the recommended values (4-14 degrees).
 Conclusion: Significant discrepancy exists between the recommended guidelines and the clinically achieved convergence angle values recorded in this study. The recommended values were rarely achieved. Operator experience seems to be an important determinant for achieving better convergence angle values.