Feather Edge Preparation

The feather edge preparation (or knife edge preparation) is a popular preparation by doctors who like metal collars or full gold crowns. The advantage of this prep is that the crown margin can be extended into the sulcus (sub-gingival). Until recently, this prep was not available for All Ceramic materials - specifically pressed ceramics such as E.Max or other All Porcelain crowns. These materials required a shoulder or chamfer prep to allow sufficient space for porcelain buildup. However, with newer products such as full contour milled zirconia (also known as All Zirconia or Bruxzir by Glidewell Dental Labs), a feather edge prep is now possible. The advantage of the All Zirconia is that it can be made thin - 0.5mm thickness is sufficient (although 1mm is preferred). The main disadvantage is that the aesthetics are not ideal. Currently, milled crowns cannot achieve the shade variation of standard porcelain and are typically opaque. As such, we really do not recommend the All Zirconia for teeth bicsupid forward. However, it is a very nice material for posterior teeth and can replace the standard gold crown as it requires between 0.5mm-1mm occlusal reduction only.