Microabrasion on dental restorative porcelains and amalgam

There are a number of different mechanisms by which tooth wear occurs, including tooth-tooth contact, temperature changes and the chemical environment inside the mouth; these different mechanisms can occur simultaneously. 'Attrition', 'abrasion', 'abfraction' and 'erosion' are the main terms used to describe tooth wear. Abrasion occurs in the presence of abrasive particles from various sources. Damage by abrasion occurs on enamel or dental porcelain surfaces when particles become trapped in the occlusal zone, a mechanism called three-body wear abrasion. In the current study, three commercial dental powder-liquid porcelains (used as restoratives in posterior teeth) and one amalgam restorative were tested using an in vitro method with a Plint TE66 microwear tester. Wear conditions were 0·25 N of load applied, 0·1 m s^-1 of ball speed and 7?98 m of sliding distance at room temperature. Mixtures of distilled water and artificial saliva were used as liquid suspension, each containing 22 vol.-% silicon carbide (SiC F1200), with an average size of 4 mm. Lost volume and wear coefficient of the restoratives were determined. Scanning electron microscopy images were obtained, the wear patterns (scars) on the specimens were analysed and the wear mechanisms (including brittle fractures for the porcelains, and ploughing, cutting and plastic deformation for the amalgam) were identified and discussed. Wear topography was obtained from atomic force microscopy images.