ABSTRACT
Biomedical grade zirconia was invented and prepared for the rst time over 25 years ago, but zirconia (ZrO2) as a new biomaterial was rst introduced in the 1990s as a femoral head material in orthopedics as a hip prosthesis [3]. Subsequently, its properties as a dental biomaterial opened the design and wide applications of allceramic restorations with higher success and reliability. Today, long span bridges and complex all-ceramic restorations are feasible due to their unique biomechanical properties. With the current computer-aided design/ computer-aided manufacturing (CAD/CAM) technology, the design, accuracy, and production of zirconia frameworks are rapid, reliable, and economically favorable [4]. Surprisingly, only a few cases of clinically observed fractures are reported [5]; however, there are several reports about minor chip-off fracture of the overlying veneer ceramic [6].
