Efeito da aplicação prévia de um dessensibilizante experimental contendo um compósito de hidroxiapatita e capsaicina sobre a difusão de peróxido de hidrogênio na câmara pulpar

Abstract

Objectives: To evaluate of a prior application of an experimental desensitizer containing a hydroxyapatite and capsaicin compound in different concentrations on peroxide hydrogen diffusion into the pulp chamber, bleaching efficacy and on enamel surface alterations in extracted human teeth submitting to in-office dental bleaching with 35% hydrogen peroxide (HP). Material and methods: 40 sound premolars were randomized in 5 study groups (n = 8); a negative control group, which did not have submitted to treatment and another four groups treated with the different experimental conditions according to the different HAp-CAP concentrations: 0% or positive control, 0.1%, 1% and 5%. After desensitizers gels application for 10 minutes, the bleaching gel with 35% HP was applied on enamel surface for 50 minutes. The HP concentration (μg/mL) on the pulp chamber was measured by UV – Vis spectrophotometer. The bleaching efficacy was measured by digital spectrophotometer (ΔEab, ΔE00 and ΔWID) before and after 7 days bleaching procedure. After treatment of each experimental condition, the fragments of thirds molars (n = 80) were submitted to field emission scanning electron microscope and energy dispersive X-ray spectroscope (FEG – EDS), Vickers microhardness (VNH), Raman spectroscopy and nanoroughness test by atomic force microscopy (AFM) in order to evaluate morphologic and chemistry changes on enamel surface. ANOVA one – way, Dunnett’s test and the post – hoc Tukey’s test was performed to data analyze (α = 0.05). Results: The groups with any HAp-CAP concentrations (0.1% - 1% - 5%) showed significant differences, with lower PH concentrations values on pulp chamber when compared to positive control group (p < 0.001), on the other hand, did not show significant differences between them (p > 0.05) or when compared with negative control group (p > 0.05). There were no significant differences in bleaching efficacy between groups with different HAp-CAP concentrations and positive control (p > 0.05) under the different color parameters used. The HAp-CAP 5% did not show significant differences in microhardness (VNH) when compared to negative control (p = 0.993), also did not show significant differences in nanoroughness (Ra) between different studies groups (p = 0.498). Conclusion: The desensitizers gels with HAp-CAP at concentrations as low as 5%, can reduced hydrogen peroxide inside the pulp chamber after in-office tooth bleaching with 35% HP, without interfered in the bleaching efficacy.