Resistance of Glaze Application on Indirect Restorative CAD/CAM Materials Against Abrasive Toothbrushing Wear

To evaluate the effect of toothbrushing on the surface roughness (Sa), roughness profile (Rv), gloss units (GU), and surface morphology of three glazed ceramics.

Specimens (n = 7) were made from the following different CAD/CAM materials and evaluated: lithium disilicate-based glass ceramic (EM); zirconia-reinforced lithium silicate glass ceramic (CE); and 6 mol% yttria partially-stabilized zirconia (IN). IPS e.max CAD (EM) and InCoris (IN) specimens were sintered, and all groups were prepolished and glazed according to the manufacturer's recommendations using IPS Ivocolor Glaze Paste (Ivoclar Vivadent) or Universal Overglaze High Flu (Dentsply/Sirona). Sa, Rv, GU, and morphology were analyzed before and after brushing at 30,000, 120,000, and 180,000 cycles. The data of Sa and GU were analyzed with ANOVA two-way and post hoc Tukey tests (α = .05). Rv was analyzed with Kruskal-Wallis and Student-Newman- Keuls tests. Surface morphology was analyzed qualitatively.

Sa decreased significantly after 180,000 toothbrushing cycles for all materials tested. CE showed higher Rv than EM and IN, and IN showed the highest GU after 180,000 toothbrushing cycles, which promoted a polishing effect for all materials.

Long-term toothbrushing did not jeopardize the glazed surface of all tested materials compared to lack of brushing.