Low-temperature Degradation of Zirconia-based All-ceramic Crowns Materials: A Mini Review and Outlook

Zirconia-based bioceramics have been widely applied in the field of prosthodontics owing to its desir- able mechanical performance, biocompatibility and aesthetics. However, the low-temperature degradation （LTD） of tetragonal zirconia （ZrOJ under intraoral condition can lead to the deterioration of mechanical properties of ZrO2 dental crowns, which contribute to many clinical failures in long-term observations. The long-term tetragonal phase stability and mechanical properties of yttria-stabilized tetragonal zir- conia polycrystal （Y-TZP） are influenced by grain size of ZrO2 crystals, distribution and properties of stabilizers, the humid environment, etc. However, it is still difficult to control the abovementioned factors at the same time. This review summarizes the major advances in researches dealing with LTD and clari- fies the obstacles to stabilization of the tetragonal ZrO2. Furthermore, the suggestions on improving the LTD resistance of tetragonal ZrO2 are proposed, which is the catalyst to promote the long-term stability of ZrO2-based all-ceramic crowns.