Infuência de tratamentos clareadores over-the-counter nas características físicas do esmalte

Abstract

Tooth whitening seeking has promoted greater availability and use of commercial overthe-counter materials that are easily accessible, without professional control, and with questionable whitening efficacy and effectiveness. The aim of the study was to determine the influence of over-the-counter whitening agents on the physical characteristics of the enamel. This is an in vitro laboratory research approved by the Ethics Committee (nº 3,420,944). Thirty eight human teeth extracted due to periodontal or orthodontic causes were collected, cleaned, disinfected and frozen. Teeth were cut, sandblasted with increased granulation sandpaper, stored in artificial saliva at 37ºC and randomly allocated in 5 groups according to the bleaching agent of 35%, 6% and 0.1% of hydrogen peroxide with and without brushing, applied directly for 7 days. Dental hardness and color were evaluated before and after treatments. Knoop hardness was performed in a microdurometer with a constant load of 50g for 5 seconds. Tooth color was obtained using a calibrated spectrophotometer. To evaluate the color change, the values of the three color coordinates (L *, a *, b *) were obtained. For the statistical analysis, the Shapiro-Wilk normality test, ANOVA and Holm Sidak analysis of variance for multiple comparisons were used, with a significance level of 5% (p <0.05). After treatment, hardness decreased significantly in the 6% hydrogen peroxide and brushing group (p <0.05). The combination of bleaching agent with 0.1% acid concentration and brushing did not influence the enamel hardness. The highest color change was in the groups of 35% and 6% hydrogen peroxide (p <0.05), which also showed the greatest change in luminosity, being different from the other groups (p <0.05). Red tones decreased in intensity in all groups. The group of peroxide 0.1% and brushing increased the intensity of yellow color and the other groups decreased the intensity of blue color. Highest change in red and blue tones was observed in the 35% hydrogen peroxide group (p <0.05). The concentration of hydrogen peroxide and brushing influenced the hardness and color of the enamel. Agents based on 35% and 6% hydrogen peroxide bleached enamel color.