Wear behavior of zirconia substrates against different antagonist materials
Objective:
This study assessed the wear behavior of different zirconia substrates with distinct surface roughness against different antagonist materials.
Method:
Hemisphere-shaped specimens (diameter 5 mm) made out of different materials (VM9, Vintage ZR, IPS e.max Press, and human enamel) were used as antagonists against plates of three zirconia materials (P-NANOZr, Cercon HT, and Zenostar) with different surface roughness (smooth [Ra = 0.01], moderate [Ra = 0.1], and rough [Ra = 1]). Each group (n = 7) was exposed to thermomechanical fatigue in a mastication simulator to simulate 5 years of clinical service. All specimens were scanned using a laser scanner and volumetric loss was quantified. Scanning electron microscopy was used to evaluate wear pattern, while Raman spectroscopy was employed to determine the crystalline property of zirconia specimens.
Results:
For zirconia, the smallest volumetric loss was recorded with smooth P-NANOZR against enamel antagonists (0.002 ± 0.002 mm³), whereas the greatest loss was observed with rough Cercon HT against Vintage antagonists (0.37 ± 0.14 mm³). For antagonists, smooth Zenostar against enamel antagonists yielded the smallest volumetric loss (0.03 ± 0.02 mm³), whereas the greatest loss values were recorded with rough Zenostar against VM9 antagonists (2.67 ± 0.35 mm³). A positive correlation was found between surface roughness of zirconia specimens and volume loss of base and antagonist specimens. PNANOZR showed less wear compared to other zirconia materials. The wear pattern was comparable among different specimens. Artificial aging did not influence the levels of tetragonal and monoclinic phases of different zirconia materials.
Conclusion:
While microstructure shows a relatively smaller effect, surface roughness of zirconia has the greatest effect on its wear and on the wear of antagonists.
