Effect of tooth bleaching associated with different thickeners, dentifrices and salivary fluxes on the physical properties of dental enamel

Abstract

The objective of this study was to evaluate in situ the physical properties of 10% Carbamide Peroxide (PC) associated with a Sulfonic Acid Copolymer (CPa) (Study I), to evaluate in situ the physical properties of dental enamel submitted to bleaching with 10% carbamide peroxide with natrosol thickener in patients with low salivary flow (Study II) and to investigate in situ the effectiveness of different dentifrices on the bleached enamel associated with the low salivary flow (Study III). The studies will use bovine enamel blocks (4x4mm, n = 12) that will be randomized between 12 volunteers for Study I and 24 volunteers for Studies II and III (12 with reduced salivary flow and 12 with normal salivary flow). Study I will consist of a 15-day experimental phase. The specimens will be submitted to different treatments with the following gels: Carbamide Peroxide + Carbopol, Carbamide Peroxide + Carbopol experimental, Carbamide Peroxide + Aristoflex, Carbamide Peroxide, Carbopol, Aristoflex and without any treatment (control group), which should remain on the specimens for a period of 4 hours. Study II will consist of 1 phase of 14 days. The action of an experimental carbamide peroxide gel with the natrosol thickener and a commercial carbamide peroxide gel with the carbopol thickener will be evaluated. The volunteers will perform the whitening of the dental blocks for 4 hours a day for 14 days. Specimens will be stored in situ throughout the experimental period. Study III will be conducted in 6 experimental phases of 2 days. Under conditions of normal and reduced salivary flow, the effectiveness of dentifrices with different active principles will be evaluated: NaF 1450 ppm F, SnF2 1450 ppm F, arginine 8%, 5% bioactive glass and 0.5% chitosan. After bleaching, the specimens will return to the buccal medium for 24 h. In this period, for 2 times the specimens will be kept in contact with the dentifrice for the total time of 45 seconds. For the three studies, the tests of microhardness (KHN), roughness (Ra) and color (Cie Lab) will be performed. For Studies II and III, scanning electron microscopy (SEM) and quantification of the ratio of Ca / P through X-ray dispersive energy (EDS) spectroscopy will be performed. The results obtained will be submitted to the appropriate statistical test, with significance level of 5%. (AU)