The Effect of Brushing and Aging on the Staining and Smoothness of Resin Composites.

OBJECTIVES: To evaluate the staining and smoothness of resin composites undergoing aging in water or red wine and simulated brushing with or without dentifrice. METHODS: The resin composites (Z250 microfilled and Z350XT nanofilled) were tested according to aging media (deionized water or red wine) and surface treatment (no brushing, brushed with water, or brushed with dentifrice). Specimens (n = 10) were subjected to three aging cycles (5 days) of continuous immersion in the aging media; each followed by simulated brushing (585 strokes). Color coordinates (CIEL*a*b*) were measured with a spectrophotometer (SP60, EX-Rite) and roughness (Ra) measured with a contact profilometer (Surftest SJ-201P, Mitutoyo), in five time points across the experiment. Surface morphology was analyzed using AFM (SPM-9600, Shimadzu) at the end of the experiment. Data for color change (ΔE00 ) and Ra were analyzed by two-way repeated measures ANOVA and Tukey test (p < 0.05). RESULTS: Color change was observed for all groups, and it was always greater for Z350. Surface treatment did not influence the ΔE00 values for the groups aged in water. However, brushing decreased ΔE00 for the groups aged in red wine. In general, ΔE00 increased with time. Little to no differences in smoothness were observed with aging and brushing. The surface morphology analyses showed exposed/lost filler particles for brushed Z250. Such observations were not so clear for Z350. CONCLUSIONS: Within the limitations of the present experiment, short-time simulated toothbrushing with soft-bristle toothbrush and low abrasive dentifrice did not increase roughness and reduced staining for both nanofilled and microfilled materials. CLINICAL SIGNIFICANCE: Staining and surface degradation of the resin composites was reduced, but not prevented by brushing alone. Thus, minimizing the restoration exposure to staining substances is important for maintaining the aesthetic appearance of the restoration. (J Esthet Restor Dent 29:E44-E55, 2017).

Influence of Bleaching Agents on Color and Translucency of Aged Resin Composites.

OBJECTIVES: Evaluate the influence of two bleaching agents (16% carbamide peroxide-CP and 35% hydrogen peroxide-HP) on color and translucency of one resin composite (Filtek Z350 XT) in two opacities (enamel and dentin) previously aged in deionized water or red wine. METHODS: Sixty specimens of each material were divided in two groups (n = 30): aged in water or red wine for 14 days. Then the specimens were divided in three subgroups (n = 10): control/no treatment, treated with 16% carbamide peroxide (Mix Night), treated with 35% hydrogen peroxide (Mix One). Color readings were performed 24 hours after polishing (baseline); after the 14 days of aging; and after bleaching treatment. Color coordinates CIE L*a*b* were measured using a spectrophotometer (SP60 X-Rite). Color change (CIEDE2000) and translucency parameter were calculated. Data were analyzed with repeated measures two-way ANOVA, and Student-Newman-Keuls tests (5%). RESULTS: Bleaching decreased color change in stained resin composites (aged in red wine), whereas increased it in non-stained enamel resin composites (aged in water). CP had better bleaching results with stained resin composites than HP. Translucency of non-stained dentin resin composite decreased with aging, but did not change with bleaching. For stained resin composites, aging caused reduced translucency, whereas bleaching increased it. CLINICAL SIGNIFICANCE: Effective bleaching of discolored resin composites aged in an acidic and alcoholic media rich in staining agents was achieved, improving color and translucency. Carbamide peroxide showed better performance than hydrogen peroxide for the bleaching of stained resin composites. (J Esthet Restor Dent 29:368-377, 2017).