Wear of enamel and veneering ceramics after laboratory and chairside finishing procedures

Purpose. This in vitro study compared the wear of enamel against 3 types of ceramics with high esthetic potential (designed for layering techniques): feldspathic porcelain (Creation), aluminous porcelain (Vitadur alpha), and low-fusing glass (Duceram-LFC). Laboratory finishing (glazing/polishing) an d chairside polishing with a Dialite kit were simulated to compare their re spective effects on wear. Methods. Tooth-material specimen pairs were placed in an artificial mouth u sing closed-loop servohy draulics. Constant masticatory parameters (13.5 N occlusal force, 0.62 mm lateral excursion; 0.23 second cuspal contact time) were maintained for 300,000 cycles at a rate of 4 Hz. The occlusal surface of each pair was mapped and digitally recorded before and after each masti catory test. Quantitative changes were measured in terms of depth and volum e of wear. Quantitative wear characteristics were assessed by SEM. Results. Significant differences were observed (2-factor ANOVA, P<.05). Duc eram-LFC generated increased volume loss of enamel (0.197 mm(3)) compared w ith Creation (0.135 mm(3)) and Vitadur a (0.153 mm(3)). Creation exhibited the lowest ceramic wear and lowest combined volume loss (0.260 mm(3) the su m of the data for enamel and the opposing material) compared with Duceram-L FC (0.363 mm(3)) and Vitadur alpha (0.333 mm(3)). The most significant diff erences among materials were observed in volume loss, not in depth of wear. For all 3 ceramic systems, qualitative SEM evaluation revealed an abrasive type of wear. Wear characteristics of chairside polished specimens were si milar to those of laboratory finished specimens (glazed and polished). Conclusion. Duceram-LFC was the most abrasive ceramic for the antagonistic tooth. Creation ceramic was the least abrasive material and most resistant to wear. Defects, brittleness, and the possibly insufficient toughness of L FC mall explain its increased abrasiveness. Laboratory and chairside finish ing procedures gen generated similar results.