Preparation areas resisting displacement of artificial crowns

The areas of luting cement resisting rotation of artificial full crowns subjected to non-axial forces were calculated for varying values of preparation diameter, height, and convergence angle. The calculations were performed for regular conical and pyramidal preparations. The results showed that the resisting areas are larger in pyramidal than in conical preparations. Increasing the convergence angle resulted in an almost linear reduction in resisting area. The reduction was particularly pronounced for preparations of large diameters.