Crown (dentistry) - 3/4 and 7/8 Crowns

3/4 and 7/8 Crowns

There are even restorations that fall between an onlay and a full crown when it comes to preservation of natural tooth structure. In the past, it was somewhat common to find dentists who prepared teeth for 3/4 and 7/8 crowns. Such restorations would generally be fabricated for maxillary second premolars or first molars, which might only be slightly visible when a patient smiled. Thus, the dentist would preserve healthy natural tooth structure that existed on the mesiobuccal corner of the tooth for aesthetic purposes, the remainder of the tooth would be enclosed in restorative material. Even when porcelain-fused-to-metal and all-ceramic crowns were developed, preserving any amount of tooth structure adds to the overall strength of the tooth. Some dentists feel that the structural benefits of retaining some of the original tooth structure are more than offset by the potential problems of having a significantly longer marginal length (the "seam" on the surface between the crown and the tooth).