Convergence of the axial walls of full veneer crown preparations in a dental school environment.

This research report used a simple and accurate method of measuring the convergence of full veneer crown preparations. A random sample of 909 dies was selected from all dies of full veneer crown preparations done at the University of Colorado, School of Dentistry student clinic over a 6-year period. All preparations were accomplished by third- and fourth-year dental students under either normal clinic conditions or under special (proficiency) testing conditions. The mean convergence angles were 19 degrees (S.D. +/- 9.8 degrees) for nonexamination conditions and 15.7 degrees (S.D. +/- 5.5 degrees) for examination procedures. These angles are far in excess of those normally recommended in the fixed prosthodontic textbooks. The values obtained in this investigation agree with the findings of most of the current published studies on the subject.