Abstract
Purpose: After dental treatment is completed, mechanical tooth cleaning using prophylaxis paste is always performed as preventive maintenance. However, it is not yet known how the load during mechanical cleaning and the cleaning time per tooth surface affect the surface properties of computer-aided design/computer-aided manufacturing (CAD/CAM) crown restorative materials. In this study, we therefore examined the effects of mechanical cleaning load and time on the surface gloss and roughness of various CAD/CAM crown restorative materials.
Materials and Methods: Four types of CAD/CAM blocks for crown restoration were used. Shofu Block HC, Estelite Block, IPS Empress CAD, and Celtra DUO. These blocks were cut to produce 3-mm-thick plate samples. After each specimen was polished, it was mechanically cleaned using a prophylaxis brush (Merssage Brush) and one-step prophylaxis paste (Prophy Paste PRO) at 2,500 rpm under the following conditions: Group Ⅰ, 100 gf, 10 s×4 cycles; Group Ⅱ, 100 gf, 30 s×4 cycles; Group Ⅲ, 300 gf, 10 s×4 cycles; and Group Ⅳ, 300 gf, 30 s×4 cycles. Surface gloss and roughness were measured before and after cleaning.
Results: For CAD/CAM ceramic blocks (IPS Empress CAD and Celtra DUO), the changes in surface gloss and roughness were small during mechanical cleaning. In contrast, the gloss of composite-based CAD/CAM blocks (Shofu Block HC, Estelite Block) decreased when mechanical cleaning was performed with either 100 gf or 300 gf. In particular, when mechanical cleaning was performed with 100 gf, the surface gloss was significantly reduced by cleaning for 30 s rather than for 10 s.
Conclusion: When mechanical cleaning is performed using one-step prophylaxis paste, it seems preferable to apply a slightly larger load to the composite resin-based restorative material for a shorter time rather than a smaller load for a longer time.
