Who cuts the better occlusal rest seats? GDPs versus academics

Objective The aim of this study was to test whether rest seats cut by a group of gene ral dental practitioners for a removable partial denture differed in size a nd shape from those prepared by either a group of postgraduate students or their academic teachers. Method The occlusal surfaces of a number of plastic teeth were scanned by a laser profilometer. Each tooth was then placed in a set of articulated phantom he ad dental arches. 30 dental practitioners, 16 postgraduates and 11 dental a cademics were asked to cut a rest seat preparation in the mesial marginal r idge suitable for the construction of a removable chromium cobalt partial d enture. The tooth was removed from the models, rescanned, and this data con verted to grey level images for measurement of the width, length and area o f each rest seat. Depth was calculated as the difference between the pre an d post preparation scanned profiles. Results There was a wide variation in the size of the individual rest seat preparat ions. There was no significant difference between the measured parameters f rom the images of the preparations made by academic staff and postgraduate students. The two sets of data were therefore combined. The length, width a nd area of the rest seats prepared by the staff and postgraduate group were significantly greater than those cut by the dental practitioner group. How ever, there was no significant difference in the depths measured. The outli ne form of the rests prepared by the dental practitioners was often round w ith sharply defined margins contrasting with the smooth triangular preparat ions of the staff and postgraduates. Conclusion A 'refresher' in tooth modification for GDPs designing partial dentures wou ld improve the longterm success of the prosthesis.