How and when does fabrication damage adversely affect the clinical performance of ceramic restorations?

OBJECTIVES: As compared to factory-processed ceramic parts, one unique trait of all-ceramic dental restorations is that they are custom-fabricated, which implies a greater susceptibility to fabrication defects. A variety of processing techniques is now available for the custom fabrication of all-ceramic single and multi-unit restorations, these include sintering, heat-pressing, slip-casting, hard machining and soft machining, all in combination with a final staining or veneering step. All these fabrication techniques, from shaping to firing, are associated with the production of flaws of various shapes and sizes, in conjunction with thermal residual stresses, all of which are capable of inducing failure.
METHODS: This review will examine the various types of fabrication damage inherent to each technique and attempt to establish a relationship between fabrication defects and clinical performance of all-ceramic dental restorations with particular attention to their longevity in vivo.
RESULTS: Failure mechanisms in dental ceramics can be very complex and often involve the combination of physical factors, to which are added patient and clinician-related variables such as restoration design and in vivo conditions. SIGNIFICANCE: Tremendous progress has been made in understanding the failure mechanisms of all-ceramic dental restorations over the past thirty years. It remains that there is still a need for laboratory tests that usefully simulate clinical conditions.