Polish retention of ceramic-polymer CAD/CAM materials

New ceramic-polymer millable materials that may be less resistant to the abrasive effects of toothbrushing than glass-ceramic materials have been introduced recently. The purpose of this study was to evaluate the polish retention of ceramic-polymer materials after mechanical toothbrush abrasion. Four ceramic-polymer materials (Enamic, Lava Ultimate, CeraSmart, and Block HC) were compared to a lithium disilicate glass-ceramic material (IPS e.max CAD). After 10 specimens of each material were polished, baseline area surface roughness (Sa) measurements were made. Specimens were then placed in a toothbrushing machine for 60,000 strokes, simulating 8 years of brushing. Surface roughness measurements were repeated after 30,000 and 60,000 brush strokes. At the end of the brushing, IPS e.max CAD and Enamic had the lowest mean Sa values (0.50 [SD 0.17] and 0.55 [0.13] µm², respectively), while Block HC had the greatest (1.10 [0.10] µm²). Lava Ultimate and CeraSmart demonstrated intermediate Sa values (0.81 [0.14] and 0.72 [0.11] µm², respectively). Only IPS e.max CAD had no statistically significant increase in surface roughness after toothbrushing.