Effect of Activated Charcoal Toothpaste on Color Stability of Bleached Teeth Immersed in Different Drinks.

OBJECTIVE: This study aimed to evaluate the effect of activated charcoal toothpaste on the color stability of teeth subjected to tooth bleaching and pigmenting agents. METHODS: A total of 120 bovine crowns were randomly divided into 12 groups (n=10) according to two study factors: staining solutions (three levels): saliva (control), coffee, and red wine; and toothpaste (four levels): BPC, Bianco Pro Clinical (Bianco Oral Care) (Control); BIW, Black is White (Curaprox); BCA, Bianco Carbon (Bianco Oral Care); and NAT, Natural Suavetex (Suavetex). The samples were subjected to office bleaching with a 35% hydrogen peroxide-based gel (Whiteness HP Blue, FGM), followed by immersion in the solution for 45 minutes per day and daily toothbrushing for 7 days. The color (ΔE) and luminosity changes (ΔL*) were measured using reflectance spectroscopy (Vita EasyShade). The CIE values (L*, a*, b*) were measured at baseline after bleaching (T0) and immediately after immersion in solution each day (Ti1-Ti7) and after all toothbrushing cycles (Tb1-Tb7). ΔE and ΔL were analyzed using a two-way analysis of variance and Tukey's test (α=0.05). The clinically unacceptable level of ΔE > 3.3 was used to evaluate the color change. RESULTS: The color change was significantly influenced by the staining solutions and toothpastes (p<0.001). The color change (ΔE) was significantly higher when immersed in wine than in coffee, and lower ΔE values were observed for artificial saliva (control), irrespective of the toothpaste used. In artificial saliva, BPC, BIW, and BCA resulted in significantly lower ΔE values than NAT, which presented a clinically unacceptable level of dental color change (ΔE>3.3). Coffee resulted in a lower (L*) reduction than wine, irrespective of the toothpaste used. CONCLUSION: Charcoal toothpastes resulted in a color change on the surface of the tooth enamel (ΔE). The bleaching effect of the charcoal toothpastes and control evaluated in this study partially reduced the color changes on the surface of the tooth enamel caused by staining solutions but was unable to reestablish the measured values to the baseline. For teeth immersed in artificial saliva, the color change was not noticeable in BCA, BIW, and control-BPC (ΔE≥3.3), except for NAT, which showed a significant color change.

Post-gel and Total Shrinkage Stress of Conventional and Bulk-fill Resin Composites in Endodontically-treated Molars.

CLINICAL RELEVANCE: The clinician should consider the polymerization shrinkage stress when selecting a composite resin for posterior restorations. The use of post-gel shrinkage values should guide the selection of a composite resin for posterior teeth. SUMMARY: Objectives: The objective of this study was to evaluate the effect of the method used for calculation of polymerization shrinkage, total or post-gel, on the shrinkage stress of conventional and bulk-fill composite resins for restoring endodontically treated teeth using finite element analysis.Methods and Materials: Four composite resins were tested for post-gel shrinkage (P-Shr) by the strain-gauge test and total shrinkage (TShr) using an optical method (n=10). Two conventional composite resins, Filtek Z350 XT (3M-ESPE; Z350) and TPH3 Spectrum (Dents-ply; TPH3) and two bulk-fill composite resins. Filtek Bulk-Fill Posterior (3M-ESPE; POST) SureFil SDR flow (Dentsply; SDR) were tested. Elastic modulus (E), diametral tensile strength (DTS), and compressive strength (CS) were also determined (n=10). The residual shrinkage stress was evaluated by finite element analysis with four restorative techniques: incremental with Z350 and TPH3; SDR/TPH3 (two bulk increments of 4 mm and two occlusal increments); and two bulk increments of 5 mm for POST. Data for P-Shr, T-Shr, E, DTS, and CS were analyzed by analysis of variance and Tukey's test (α=0.05), and residual shrinkage was analyzed quantitatively and qualitatively by the modified von Mises criteria.Results: SDR had the lowest CS values, POST and TPH3 had similar and intermediate values, and Z350 had the highest CS. TPH3 and Z350 had similar DTS values and values higher than SDR. Z350 and POST had higher P-Shr, and SDR had lower T-Shr. T-Shr resulted in higher shrinkage stress than P-Shr values. SDR/TPH3 resulted in higher shrinkage stress when using T-Shr and lower values when using the P-Shr value.Conclusion: T-Shr resulted in higher stress in the enamel and in root dentin close to the pulp chamber than P-Shr values. The selection of the T-Shr or P-Shr changed the ranking of the shrinkage stress of the tested composite resin.