Effects of Desensitizing Dentifrices on the Reduction of Pain Sensitivity Caused by In-office Dental Whitening

Patients who sought the postgraduate dental clinic for whitening were invited to participate in the study. They were informed by the researcher (dentist) about all the aspects of the study and who might participate or discontinue the participation at any moment during the treatment. In addition, it was clarified that their participation was voluntary and refusal to participate would not result in any penalty or loss of benefits.

The evaluation of the tooth color was performed by using a spectrophotometer (Easyshade, Vident, Brea, CA, USA). The color was analysed with the tooth hydrated before of the start the first whitening session and one week after. The spectrophotometer was always used in the same position by a silicon guide, which was prepared with dental arch molds by adding high viscosity vinyl polysiloxane material (Express XT, 3M ESPE, Sumaré, SP, Brazil). After polymerization, an opening was made in the mold corresponding to the buccal surface of the upper central incisors, allowing the color of the tooth to be evaluated with the tip of the spectrophotometer at the height of the middle third.

The clinical procedures were performed under relative isolation using lip retractor (Arcflex, FGM, Joinville, SC, Brazil) and dental cotton rollers to apply a gingival protection barrier (Top Dam, FGM, Joinville, SC, Brazil) extending from right first molar to left first molar in both arches.

The gingival protection barrier was placed over the margins and gingival papilla corresponding to the areas receiving the whitening gel with approximately 3 mm in height and photopolymerized for 20 seconds in each group of three tooth. Photo-activation was performed with high power LEDs (light intensity = 600mw / cm²) (RadiiCal, São Paulo, SP, Brazil).

The desensitizing gel containing 5% potassium nitrate associated with 2% sodium fluoride (Desensibilize KF 2%, FGM, Joinville, SC, Brazil) was applied with a microbrush (Brush KG, KG Sorensen, Cotia, SP) on the buccal surface from right first molar to left first molar in both arches and remaining for 10 minutes. Then, the desensitizer was then removed with water jet and disposable plastic suction cannula.

The handling of 35% hydrogen peroxide (Whiteness HP, FGM, Joinville, SC, Brazil) followed the manufacturer's recommendations, which consisted of mixing 3 drops of 35%hydrogen peroxide for 1 drop of thickener, with this mixture being sufficient for application to at least three tooth. The gel remained in contact with the buccal surface of the tooth for 15 minutes and was removed with disposable plastic suction cannula and water wash. This procedure was performed three times per clinical session. The volunteers underwent three whitening clinical sessions with one week interval between them.

Among the clinical whitening sessions, each volunteer used an unidentified dentifrice corresponding to their experimental group, which was previously defined by means of a draw made by a dentist who did not participate in the study. Thus, the researcher (dentist) who provided the dentifrice and the volunteer were not aware of which experimental group belonged (i.e. double blind).