Knowing the whitening therapy: effect of the application site and the volume of whitening gel on the chromatic alteration and postoperative sensitivity - randomized clinical trial

Author(s)

Lara Maria Bueno Esteves

• Document type: Master's Dissertation
• Press: Araçatuba. 2020-12-01.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araçatuba
• Defense date: 2020-11-19
• Advisor: André Luiz Fraga Briso

Abstract

Although the success of tooth whitening was considered to be dependent on the dosage used, this procedure still has important gaps with regard to the dosage used and the form of application of the whitening products. The aim of this study was to evaluate clinically the effect of the positioning of the bleaching gel and the influence of its volume on the chromatic alteration and on the postoperative sensitivity. For the study of the positioning of the bleaching gel, thirty patients were selected and allocated into three groups (n = 10): GI- application on the cervical half, GII- application on the incisal half, GIII- application on the entire buccal surface. The amount and time of application of the 35% hydrogen peroxide gel were standardized. The color analysis was performed by ΔE and WID (lightening index), using the values obtained in the readings performed on a digital spectrophotometer. The readings were made in the cervical and incisal regions of the teeth. Spontaneous sensitivity was assessed using a questionnaire and the sensitivity caused by thermo-sensory analysis (TSA). The analyzes were carried out in 5 stages: baseline, after the 1st whitening session (S), 2ºS and 3ºS and 14 days after the end of the whitening. The data were analyzed using the linear regression model with mixed effects and post-test using orthogonal contrasts (p <0.05). It can be seen that, regarding the chromatic alteration, although the incisal region is momentarily favored by the application of the gel, at the end of the treatment the restriction of the application site to the cervical or incisal region provided results similar to those obtained when the gel was applied throughout the vestibular face. As for sensitivity, only the group that received whitening gel in the cervical portion had spontaneous sensitivity. In the thermosensory analysis, the group that received gel on the vestibular face had less influence on the threshold of thermal sensation. In parallel, in the second study, in which the influence of the volume of the bleaching gel was evaluated, the thirty patients were allocated into three groups: GI-0.025mL, GII-0.05mL, GIII-0.10mL, and received the product only in lower canines (n = 10). The chromatic alteration analysis was performed using a portable digital spectrophotometer, being calculated the values of ΔE, ΔL *, Δa *, Δb *, as well as the bleaching index (WID). Spontaneous sensitivity was assessed by applying a questionnaire and sensitivity by thermo-sensory analysis. The analyzes were carried out in 5 stages: baseline, after 1st, 2nd and 3rd whitening sessions and 14 days after the end. Data were analyzed using two-way ANOVA tests with repeated measures and Tukey's post-test (p <0.05). It was observed that ΔE and ΔL * were similar between the groups at the end of the bleaching therapy. The values of Δa *, Δb *, as well as the WID were more intense in the group that received 0.10mL, which also showed the highest spontaneous and stimulated sensitivity. Thus, through the two studies carried out, it can be concluded that at the end of the treatment the chromatic alteration does not depend on the application site of the whitening gel, however, the incisal region, presents chromatic saturation faster than the cervical region. It was also found that the greater the volume, the greater the bleaching response in the specific coordinates and in the bleaching index, however, showing no difference in the chromatic alteration and in the analyzed luminosity. The tooth sensitivity was more intense when the application of the gel was concentrated in the cervical region, being also markedly proportional to the volume used. Thus, in relation to the analyzed dental group, the reduction of the positioning of the bleaching gel to the incisal and the use of an intermediate volume (0.05mL), provided positive effects for the chromatic alteration and reduction of the sensitivity response. (AU)

• FAPESP's process: 18/11636-7 - Knowing the bleaching therapy: effect of the amount and area of gel application on the color alteration and the postoperative sensitivity
• Grantee: Lara Maria Bueno Esteves
• Support Opportunities: Scholarships in Brazil - Master