Effect of finishing, polishing and glazing on surface roughness and flexural strength of different ceramic materials

Abstract

Summary The increased popularity of all-ceramic materials as an alternative to metal-ceramic restorations is attributable to their excellent esthetics in matching the natural tooth structure in terms of color, translucency and biocompatibility. However, they exhibit low mechanical properties. The final occlusal adjustment of the ceramic restoration with abrasive rotary instruments has to be made after cementation, and this procedure creates a rough surface, which can facilitate biofilm accumulation producing gingival inflammation or can increase the wear of other restorative material. Occlusal adjustment also can create a significant increase in surface roughness, which can affect the flexural strength of ceramic material. Surface roughness is a factor that affects the flexural strength of ceramic restorations beside its microscopic defects. It is measured on the outer layer of ceramic material as most dental ceramic restorations are subjected to selective grinding in order to adjust the occlusal relation. Flexural strength is one of mechanical properties of ceramic materials that gives the priority for the material to be used in areas of high mastication forces, it also affected by heating during pressing of ceramic material due to increase the crystalline size that is beside porosity which act as stress concentration which will decrease the flexural strength of ceramic material.