In-vitro Comparison of Zirconia Polishing Systems After Simulated Occlusal Adjustment

Objectives: Occlusal adjustment of zirconia restorations may often be necessary, but creates a rough surface. Polishing the adjusted surface is mandatory for preventing damage to the opposing dentition. This study compares three polishing regimens for achieving smooth surfaces.
Methods: : Twenty-seven zirconia tiles were sectioned from Inceram YZ blocks (Vita) and sintered. The specimens measured 1.5 x 8 x 12 mm. Treatment was applied in 3 steps:
Step 1: Adjustment grinding using Zircon Master Kit diamond Bur # Z732 (Meisinger).
Step 2: Polishing using low speed LS-517 Zir-Cut rubber polishing cups (Axis Dental).
Step 3: Specimens were randomized into three groups (n=9) and polished using diamond pastes from 3 manufacturers: Group 1: Diamond paste from American Dental Supply. Group 2: Diamond paste (Zircon-Brite) from Dental Ventures of America. Group 3: Diamond paste (Allbright) from Harvest dental Lab.
Surface roughness was measured by a profilometer (SJ-201, Mitutoyo Corp., Japan) with a 2 um diamond stylus. Gloss indexes of the tiles were measured by a gloss meter (Novo-curve, Rhopoint Instruments, UK) after each grinding and polishing stage. Results were analyzed by Oneway ANOVA using JMP 12.
Results: Are presented in Table 1 and Figure 1.
Conclusions: All 3 polishing systems tested rendered smooth surfaces with Ra levels significantly smoother than the adjusted surfaces. The gloss index of Group 3 showed a lower value than Groups 1 and 2.