The contribution of a pinhole to the retention and resistance form of veneer crowns.

This research quantitatively compared the retention and resistance of various designs of maxillary premolar partial veneer crown preparations. Crowns were evaluated with and without proximal boxes and occlusal pins. In the absence of boxes or grooves, pins markedly enhanced both retention and resistance. In the presence of proximal boxes, pins contributed only to retention and had no significant effect on resistance. If pins are used, the cement should be spiralled into the pin hole. As resistance is usually the more crucial parameter in preparation designs, it seems that wherever efficient axial modifications can be incorporated, the pinhole modification may be of little advantage.