Figure 1.

Three different fracture modes have been observed with zirconia‐based crowns fractured in clinical use (ongoing retrieval study). (A) Total fracture in two to three pieces, usually originating in the proximal margin area. (B) Total fracture in three pieces or more, with the fracture originating in the intaglio occlusal wall in a thin region of the crown. (C) Margin chip, usually observed on buccal or lingual flange. Open arrows indicate fracture origin. Black arrows indicate direction of crack propagation.