Dental zirconia ceramics, with their excellent mechanical properties, high temperature stability, biocompatibility and low thermal conductivity, have been widely used for clinical all-ceramic restorations, especially for full crown and fixed bridge of posterior teeth. However, under comparatively low temperature in humid environment, partially stabilized tetragonal zirconia ceramic tends to transform into monoclinic crystal. This phenomenon is called low temperature degradation（LTD）, which will result in poor mechanical properties of the material. This article discussed the LTD phenomena of the partially stabilized tetragonal zirconia and its related influencing factors, and possible approaches to improve its low temperature degradation resistance were proposed as well.
