Why choose a crown with a shoulder preparation?

In brief:
Gum inflammation and periodontal disease develop much more readily around crowns without a shoulder preparation than around those with one. For metal-ceramic crowns, a shoulder preparation also gives the crown margin a more attractive appearance.

In detail:

In general, gum inflammation can develop slightly more easily around an artificial material, such as a filling or crown, than around a healthy natural tooth, even when the restoration is made as well as possible. This becomes more likely the further the crown extends below the gum line. For aesthetic reasons, the outward-facing margin of a crown is usually placed below the gum. The margin also has to be placed below the gum when the tooth being saved is severely damaged down to or below gum level.

A crown without a shoulder preparation is more likely to cause gum inflammation and periodontal disease because it has a ledge at its margin. A crown with a shoulder preparation blends smoothly into the tooth without a noticeable ledge. Plaque accumulates more readily on a ledge, where bacteria can also hide. A shoulder preparation therefore minimises the crown’s contribution to gum and periodontal problems.

The aesthetic difference applies to porcelain crowns with a metal framework. A shoulder preparation allows a thicker layer of porcelain at the margin, concealing the metallic colour that might otherwise show at the edge.

Explore the treatments related to this topic.
Replacing missing teeth »