Comparison of convergence angles achieved in posterior teeth prepared for full veneer crowns

This study compares the convergence angle of preparations for posterior gold crowns made by fourth/ fifth year undergraduate dental students, clinical teaching staff and general dental practitioners. Sixty dies were cast from impressions previously taken of clinical preparations by clinicians within each of the four groups. Each die was trimmed and sectioned in both mesio-distal and bucco-lingual planes before being projected using an overhead projector, thereby enabling the convergence angle silhouette to be measured. The results show the greatest convergence angle range to be produced by the least experienced students (10 degrees - 82 degrees). However, no significant difference (p > 0.05) was found when students with one further year of experience were compared to experienced staff. The degree of conformity to the ideal taper (4 degrees - 14 degrees) was no greater than 50% for any of the groups.