Influence of the bubbles in the gel on the effectiveness of in-office tooth whitening in adults: randomized randomized clinical trial

Abstract

Hydrogen peroxide in high concentrations is the most commonly used substance for in-office whitening, it is a reactive species that releases products such as oxygen and hydroxyl. Manufacturers and some studies report that during this procedure, when the gel comes into contact, bubbles are formed at the interface between the bleaching gel and the tooth, and most of them mention that it is necessary to break these bubbles, justifying that this may interfere with treatment success.Therefore, this project conducted a randomized split-mouth clinical trial with the objective of evaluating whether the presence of the bleb can influence the efficacy, as well as the intensity and the absolute risk of the sensitivity of inoffice tooth whitening. The participants were divided into two groups, according to the rupture or not of the gel bubbles: Group 1: maintenance of the bubbles and Group 2: rupture of the bubbles. The protocol was performed in two sessions, with the application of a 35% hydrogen peroxide (PH) gel (Total Blanc Office, DFL, Rio de Janeiro, Brazil) on teeth 15 to 25, with a 7-day interval, whitening for 45 minutes each session. The color change was verified with the help of two color scales and a spectrophotometer, at the beginning of the study (baseline), after one week and before the second whitening session and 30 days after the end of treatment. The presence and intensity of tooth sensitivity was recorded through a sensitivity diary answered by the patient, within 48 hours after each whitening session by two scales: a visual analog scale (VAS) and a numerical rating scale (NRS). The evaluation of the whitening effectiveness in each group will be performed by the paired Wilcoxon test. The absolute risk of tooth sensitivity was compared by Fisher's exact test (p ≤ 0.05) of the total percentage of participants (absolute risk) who experienced sensitivity at least once. The intensity of this variable, will be evaluated by Mann Whitney paired test (p ≤ 0.05). No statistical difference was detected in terms of the efficacy and risk to sensitivity and intensity of sensitivity between the groups after 30 days of treatment. Approximately 93% of the participants experienced tooth sensitivity, which was mainly recorded as "mild". There was no statistically significant difference between the two groups in the subjective assessments of color, and in the objective assessment the ΔE showed no difference between the two groups. The maintenance of the bubble in the 35% hydrogen peroxide gel on the buccal surface did not affect the whitening efficacy and tooth sensitivity.