The aim of this project is to evaluate in vitro and in vivo the effect of dental bleaching agents, carbamide peroxide 16% (T1) and hydrogen peroxide 35% (T2) together with desensitizers/remineralizer agents, Sensodyne® dentifrice (D1); experimental dentifrice with 7,5% of Biosilicate micro-particles (D2); Odontis RX® dentifrice (D3); Sorriso® dentifrice (D4); Biosilicate micro-particles paste, 1:1 (D5), Desensebilize Nano P (D6), bioglass type 45S5 paste, 1:1 (D7); GC= distilled water, in the experimental groups: T1/D1; T1/D2; T1/D3; T1/D4; T1/D5; T1/D6; T1/D7; T1/GC e T2/D1; T2/D2; T2/D3; T2/D4; T2/D5; T2/D6; T2/D7; T2/GC. In the in vitro study, microhardness and roughness measurements, and images using scanning electron microscopy (SEM) will be made on samples of bovine dental enamel and dentin (4x4x3mm; n=10 per group) before and after the treatment with the bleaching gels (T1= 14 days/ 04 hours/day; T2=single session) and the desensitizers/remineralizer agents. In the clinical study, the volunteers (n=10 per group) will be evaluated regarding dentin hypersensitivity (DH), using visual analogue scale, before the beginning of the treatments (T1 and T2) and during the next 14 days (1º, 3º, 7º, 10 º e 14º days) in which the desensitizers/remineralizer agents (there´s no control group in the clinical experiments) will be applying. Data will be analysed intra and inter-group, statistically.

Background. Tooth sensitivity (TS) is a common side effect of tooth bleaching. The authors conducted a study to evaluate the efficiency of experimental desensitizing agents in reducing TS caused by bleaching agents.

Methods. To test experimental desensitizing agents in TS caused by dental bleaching the authors selected 113 participants without TS and randomly treated them with T1-16% carbamide peroxide (14 days) or T2-35% hydrogen peroxide (single session). The period of the study was 14 days. Participants (in T1 and T2) used domestic-use (DU) or in office (IO) desensitizers (D): Control Group; (DU)- experimental dentifrice with 7,5% of Biosilicate micro-particles-(D1); Sensodyne® dentifrice-(D2); (DU)-Odontis RX Sensiblock® dentifrice-(D3); (IO)-Biosilicate micro-particles paste, 1:1-(D4); (IO)-bioglass type 45S5 paste, 1:1 (D6); (IO)-Desensebilize Nano P-(D6). On days 1, 3, 7, 10 and 14, the authors received the participants to apply IO desensitizers and to record TS with Visual Analogue Scale (VAS). Data was analyzed with two-way ANOVA (considering time and desensitizing as factors) and post-hoc Bonferroni test (α=0.05).

Results. The use of experimental desensitizing agents G2 and G5 did not cause significantly difference in TS comparing to baseline. TS was not significantly different when G2 was used after 16% carbamide peroxide and G5 after 35% hydrogen peroxide application. Self-perception TS values were significantly (p<0.001) higher than recorded VAS.

Conclusions. Experimental desensitizing agents containing Biosilicate® can prevent TS caused by bleaching agents: in dentifrice form when associated to 16% carbamide peroxide and in paste, when 35% hydrogen peroxide is used.

Inclusion Criteria:

1. Patients male or females, aged between 18 and 40 years.
2. Smokers and nonsmokers.
3. Patients with good general health.
4. Patients with good oral health (no changes in hard or soft tissues).
5. Have a minimum of 24 permanent teeth present and no restorations on anterior teeth.

Exclusion Criteria:

1. Patients with a medical history marked by chronic use of analgesics, anti-inflammatory and psychotropic drugs.
2. Patients with braces or prostheses or restorations on anterior teeth.
3. Patients with periodontal disease or poor oral hygiene.
4. Patients with prior tooth sensitivity or have made use of desensitizing agents in the last three months.
5. Patients who are pregnant or nursing.
6. Patients with eating disorders or dieting too acidic.
7. Systemic conditions that predispose to tooth sensitivity.