Fractographic Analysis Of Fragments Of All-ceramic Restorations Failed In Clinic

Objectives:The clinically failed fragments of all-ceramic restorations， application offractographic theroy were analyzed for the crack origin and related defects，in order toinvestigate the actual failure mode of the all-ceramic restoration，for improving clinicaldesign and technology.Methods:Failed fragments of all-ceramic restorations(10cases) were collected in Departmentof Prosthodontics,Shanghai Ninth People’s Hospital from November2012to November2013.1.The fragments of all-ceramic were tested using Sequential X-ray FluorescenceSpectrometer,X-Ray Polycrystaline Diffractometer to detect its ingredient andstructure.2.The overall appearance of the fragments were observed using StereoMicroscope.3.The crack morphology,surface damage,the structure defects were observedto investigate the initiation and propagation of cracks utilizing the Scanning ElectronMicroscope(SEM).Results:Cycle fatigue was an important reason that resulting in the fracture of all-ceramicrestoration.Different material has different dominant fatigue damage model.Furthermore，defects of internal veneer，the interface of core and veneer including connector area，and the wear of occlusal contact area can reduce the strength of the ceramic material，whichleads to the failure of the all-ceramic restorations.Conclusions:Cycle fatigue damage was the main reason that resulting in the fracture of all-ceramicrestorations.The radial cracks is the main failure mode which is highly sensitive to thethickness of the ceramic layer.Interface of veneer and core is the weak link of the bilyerall-ceramic restorations.Stress concentration caused by structure defects and abnormalocclusion can reduce the strength of material，it is a potential risk factor of fracture.