Changes of surface characteristics after toothbrush abrasion on light-cured shade-characterizing agents for CAD-CAM composite-resin block.

Light-cured shade-characterizing agents are used for composite materials to mimic natural tooth color. Tooth-brushing abrasion tests were conducted to investigate the durability of the agents. Computer-aided design/computer-aided manufacturing (CAD-CAM) composite-resin blocks were used, and the surface was polished with #2000 SiC paper before the agent application. Four different shade agents were applied to the blocks, treated the surface no/with sandblasting. Tooth-brush abrasion tests were carried out for 20,000 cycles at a frequency of 2 Hz with 2.0 N of brushing force. Surface roughness, gloss, contact angle, and color differences were obtained. The number of repetitions was set to ten. It was found that a significant increase in surface roughness and decreases in gloss and water contact angle by tooth brushing tests were clarified. However, the color change by brushing was not significantly large. The color difference before and after applying agents and surface roughness differed in the shade differences in the agents.