ABSTRACT
To investigate the predictability and the outcome of surface modification techniques, including anodization. Four surface modification techniques were evaluated in this in-vitro study: sandblasting (S), polishing+anodizing (PA), sandblasting+anodizing (SA), polishing+etching+ anodizing (PEA). Color coordinates L*, a* and b* were collected using a spectroradiometer. Color differences between all groups were quantified by use of ΔE00. A possible influence of group membership was evaluated using 1-way ANOVA. Pair-wise inter-group comparisons were performed using post-hoc Tukey tests. PA specimens were the brightest and showed a pronounced yellowish and reddish hue. S and SA groups were significantly darker and predictability of outcome was higher compared to another groups. The most predictable surface treatment method is sandblasting. Anodizing techniques come along with the brightest and most chromatic color impression of the titanium.
Subject(s)
Titanium , Oxidation-ReductionABSTRACT
OBJECTIVE: To investigate the color stability of hybrid ceramics and to compare it to composite and lithium disilicate ceramics. MATERIALS AND METHODS: One hundred eighty samples were fabricated and processed with a semiautomatic grinding and polishing device (final step: 1200 grit). After thermocycling, samples were immersed in a staining solution (five subgroups: water, red wine, curry, black tea, cola) for 4 weeks. A spectroradiometer was used to determine the color of the samples in CIE L*a*b*. Color measurements were performed before staining (baseline, initial color), after thermocycling, after 2 and 4 week storage in staining solution and each after a two stage repolishing approach. Discoloration of specimens was calculated by means of ΔE00 compared to baseline values. RESULTS: All factors (material, staining solution, aging stage) were significantly associated with the extent of discolorations (P < .001). Maximum color changes occurred after 28 days staining (EN: ΔE00 = 4.5 ± 4.0; GB: ΔE00 = 5.0 ± 4.5; LS: ΔE00 = 3.0 ± 2.3) clearly exceeding the 50:50 threshold for acceptable color deviations. Due to repolishing, discoloration of LS samples was almost completely eliminated (ΔE00 = 0.4 ± 0.3) and significantly reduced for the other two materials (EN: ΔE00 = 1.0 ± 0.9; GB: ΔE00 = 0.9 ± 0.4; P = .428). CONCLUSION: Discoloration of hybrid ceramics ranged in-between lithium disilicate and composites, however more comparable to composites. Repolishing could reduce discolorations substantially. CLINICAL RELEVANCE: This study should help dental practitioners to estimate the color stability of common dental materials and the effect of polishing in removal of discolorations.
