Influence of Surface Coatings on Color Stability and Surface Roughness of Provisional Prosthodontic Material

Discoloration can be the problem of provisional restorations, especially in long-term treatment cases. The surface coating materials may influence the properties of provisional restorative material. This study aimed to evaluate the effect of silane-SiO2 film coating on the color stability and surface roughness of provisional fixed prosthodontic material compared to three commercial surface coating agents. A total of 160 specimens were fabricated from auto-polymerized polymethyl methacrylate resin (PMMA: Unifast Trad) and divided randomly into five groups according to applied surface coating procedures: non-coated (control) and four surface coated (silane-SiO2, Palaseal, Biscover LV, Optiglaze). Surface roughness (Ra) values were assessed by a profilometer. One specimen for each group, surface morphology was analyzed by SEM examination and element composition was analyzed by energy dispersive spectroscopy (EDS) before and after immersion in distilled water for 30 days. Color changes (AE) were measured as CIE L*a*b* value with a spectrophotometer before immersion and 1 day, 7 days, and 30 days after immersion in solutions (distilled water, tea, coffee). The data were statistically analyzed using repeated measure ANOVA on the color stability test and one-way ANOVA on the surface roughness with Bonferroni adjustment for multiple comparisons (α=.05). The mean Ra value of all groups ranged from 0.201 to 0.264. No significant differences were found among groups on surface roughness result(P>.05). Silane-SiO2 coated PMMA acrylic resin presented the lowest ΔE value in all conditions. Palaseal group showed the highest color change in the coffee solution and Biscover LV coated showed the highest color alteration in distilled water and tea solution. The different surface coatings showed significant color changes in acrylic resin (P<.05). Silane-SiO2 film-coated acrylic resin showed the most color stability compared to commercial surface coating agents and conventional polishing methods, only silane-SiO2 and Optiglaze coated groups presented a clinically acceptable color change (AE<3.7) in all solutions over the period of immersion. Silane-SiO2 coated groups showed the lowest Ra value but not statistically significant difference from other groups.