CAD/CAM leucite-reinforced glass-ceramic for simulation of attrition in human enamel in vitro.

OBJECTIVE: Investigate attrition simulation using CAD/CAM leucite-reinforced glass-ceramic antagonists on occlusal vs. buccal enamel. METHODS: Three dental materials with known wear rates (resin-modified glass-ionomer, micro-filled, and fine particle composites) validated the wear simulator (CAD/CAM glass-ceramic antagonists, 200 cycles, 80 N load, deionised water irrigation, 0.7 mm sliding movement). Following this, human molars were sectioned into paired occlusal and buccal polished samples (n = 8/gp). Exposed 1.5 mm O enamel areas were subjected to attritional wear with and without pre-immersion in citric acid (5 min, 0.3%, pH 3.8). Profilometry measured step-height enamel wear and surface microhardness at different depths was calculated using Vickers indentation at 0.1 N and 0.5 N loads. RESULTS: Dental material wear using the CAD/CAM antagonists showed consistency with previous data: mean (SD) resin-modified glass ionomer material loss of 177.77 (16.89) microm vs. 22.15 (1.30) microm fine particle hybrid composite resin wear vs. 13.63 (1.02) microm micro filled composite resin wear (P < 0.001). The coefficient of variation was less than 10%. Following validation, enamel sample wear was significantly increased when attrition was introduced (P < 0.001) independent of buccal vs. occlusal sample location (P < 0.05). Attrition resulted in occlusal wear of 26.1 +/- 4.5 microm vs. buccal 26.3 +/- 1.2 microm and attrition/erosion resulted in occlusal wear of 26.05 +/- 4.46 microm vs. buccal 25.27 +/- 1.16 microm. Whereas erosion-alone resulted in occlusal wear of 1.65 +/- 0.13 microm and buccal 1.75 +/- 0.03 microm. Microhardness testing at different loads revealed significantly greater hardness reductions in occlusal enamel vs. buccal enamel for 0.1 KgF indentations (P < 0.001) whereas in contrast 0.5 KgF indentations showed no differences. SIGNIFICANCE: Wear simulation with CAD/CAM glass ceramic antagonists produced consistent wear in dental materials and human enamel, regardless of enamel surface origin. Lighter (0.1 KgF) hardness testing of occlusal vs. buccal origin revealed damage to the mechanical integrity of the superficial worn enamel.