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Document Type

Original Study

Abstract

Statement of the problem: Ceramics and glass-ceramics are materials of choice for dental crowns due to their attractive hardness, biocompatibility, etc. However, a major problem with their usage is the observed high wear of either the opposing dental enamel or both the enamel and ceramic itself. Objective: The present study aimed at ranking and comparing the wear performance of three different ceramic systems (monolithic zirconia, lithium disilicate glass ceramic and feldspathic porcelain) and their effect on the wear and surface roughness of their antagonist enamel. Materials andmethods: Five cylindrical discs (n=5) were constructed from each of: BruxZir zirconia,IPS e.max CAD lithium disilicate based ceramic and feldspathic porcelain representing (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 samplesto 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. Results: The statistically significant highest mean material’s weight loss was recorded in porcelain group, whereas the statistically significant lowest mean weight loss was recorded in BruxZir group. The statistically significant greatestmean antagonist weight loss was recorded for e.max antagonist cusp, whereas the statistically significant lowest mean weight loss was recorded for BruxZir antagonist cusp. Surface roughness increased after wear procedure in all samples. Conclusions: Within the limitations of this in vitro study, monolithic zirconia and porcelain resulted in less wear depth to human enamel compared to lithium disilicate based ceramics (e.max CAD). However, porcelain is more affected by wear compared to zirconia.

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