Objective:To evaluate the influence of 16% carbamide peroxide (CP) containing different thickeners on the physical characteristics of a nanocomposite resin submitted or not to accelerated artificial aging (AAA).Materials and Methods:One hundred samples were randomly distributed into two groups (n = 50) according to AAA. Each group was divided into 5 subgroups (n = 10) depending on the bleaching/thickener treatment: CP + carbopol, CP + natrosol, carbopol, natrosol, and no treatment (control). The physical properties tested were color (ΔE), gloss (GU), mean roughness (Ra), and Knoop microhardness (KHN). The resin surface was performed with atomic force microscopy (AFM).Statistical Analysis:The color (variable Δ E) was assessed with two-way analysis of variance (ANOVA) and additionally with Tukey's and Dunnett's tests, the roughness values were submitted to Kruskal–Wallis, Dunn's, and Mann–Whitney's tests. Data on gloss and KHN were submitted to two-way ANOVA and Tukey's test (α = 0.05).Results:Among the physical properties evaluated, CP + carbopol promoted a reduction in composite microhardness only, thus differing statistically from the controls. As for CP + natrosol, such a change was not observed. The aging process reduced all the physical properties, thus differing statistically from the nonaging group. CP + carbopol increased the roughness and decreased the gloss of aged resins, whereas natrosol reduced gloss only, which differed statistically from the controls.Conclusions:AFM showed evidence of the loss of organic matrix and exposure to load particles in the aged samples. Therefore, the replacement of carbopol with natrosol provided maintenance of the composite microhardness following bleaching. The aging process reduced the physical properties evaluated, and some changes were enhanced by the application of bleaching.
BackgroundIn daily clinical practice, esthetics of anterior teeth is a common presenting complaint of patients.ObjectiveThis case report discusses the management of asymmetric smile associated with unsatisfactory extensive composite restorations and describes a clinical protocol using the direct composite resin for smile enhancement to restore the dental harmony of anterior teeth.MethodsThe treatment planning was based on a diagnostic wax-up and cosmetic mock-up. After clinical and patient approvals were obtained, the patient was subjected to direct and indirect restorative treatment.ConclusionNanocomposites are an effective alternative for anterior teeth restorations. Additionally, good planning enables satisfactory esthetic results, leading to the correction of an inappropriate axial inclination of incisors.
The bleaching reduced the microhardness of the nanocomposite, whereas the aging process changed all the properties studied. The bleaching favored extrinsic staining of the with aging nanocomposite.
Objective:This study aimed to evaluate the effect of the application of sodium metabisulfite (SMB) on the bond strength of bleached teeth.Materials and Methods:The study was divided into two parts. The first part evaluated the application of various concentrations of SMB for 1 h prior to the completion of bonding procedures. Fifty blocks were divided into five groups (n = 10): control; bleaching with 35% hydrogen peroxide (HP); HP + 5% SMB; HP + 12.5% SMB; and HP + 25% SMB. The second part evaluated the application of 25% gel SMB to either enamel or dentin, including the application time. Sixty blocks were divided into six groups (n = 10): control; bleaching with 35% HP; HP + 25% SMB for 1 h in enamel; HP + 25% SMB for 1 h in dentin; HP + 25% SMB for 10 min in enamel; and HP + 25% SMB for 10 min in dentin.Statistical Analysis:Following the completion of microshear bond testing, data were analyzed using one-way analysis of variance as well as Tukey's and Dunnett's tests.Results:In part 1, data analysis revealed statistical differences (P < 0.0001) between HP and HP + 5% SMB. No statistical differences were found between the control and both HP + 12.5% SMB and HP + 25% SMB. Part 2 revealed a statistical difference (P = 0.001359) only between the bleached group and others.Conclusions:The use of 25% SMB gel immediately after bleaching was able to reverse the deleterious effect of bleaching on the bond strength of dental composites to dentin.
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