WEAR PERFORMANCE OF THREE CAD/CAM MONOLITHIC RESTORATIONS: TWO-BODY WEAR AND SURFACE ROUGHNESS

Statement of the problem: The use of monolithic ceramic restorations is rapidly increasing. However, there is a rising concern about their wear performance against antagonist enamel.
Objective: The present study aimed at ranking and comparing the wear performance of three CAD/CAM monolithic ceramic materials and their effect on the wear and surface roughness of their antagonist enamel.
Materials and methods: Five cylindrical discs (n=5) were constructed from each of: BruxZir zirconia, IPS e.max CAD lithium disilicate based ceramic and Enamic hybrid ceramic representing three types of monolithic restorations (N=15). Ceramic samples were polished till obtaining convergent surface roughness values of the three materials. Enamel antagonists were prepared as sectioned buccal cusps of maxillary first premolars (N=15). Baseline surface roughness and weight values were obtained using optical surface profiler and sensitive balance, respectively, for all samples (ceramic discs and their antagonist cusps) prior to subjecting the samples to chewing simulation procedure test including the application of 5kg (49N) load for 120,000 cycle with vertical movement 1mm, horizontal movement 3mm and frequency 1.6Hz. Weight loss was calculated for all samples (ceramic discs and their antagonists) as an indication of wear. In addition, change in surface roughness was calculated using optical surface profiler. Obtained data were statistically analyzed.
Results: The statistically significant highest mean material’s weight loss was recorded in Enamic group, whereas the statistically significant lowest mean weight loss was recorded in BruxZir group. The statistically significant greatest mean antagonist weight loss was recorded for e.max antagonist cusp, whereas the statistically significant lowest mean weight loss was recorded for Enamic antagonist cusp. Surface roughness increased after wear procedure in all samples.
Conclusions: Monolithic hybrid ceramic (Enamic) and zirconia (BruxZir) produce less wear in opposing teeth compared to lithium disilicate based ceramics (e.max CAD). However, hybrid ceramic is more affected by wear compared to zirconia.