Effect of Laser and Potassium Nitrate Application on the Sensitivity Control in Bleached Teeth

Effect of Low-level Light Therapy Associated With Potassium Nitrate in the Control of Post-bleaching Dental Sensitivity: a Randomized, Double-blind, Split-mouth, Controlled Trial

To investigate the effects of desensitizing agents on the dental bleaching process, testing the hypothesis that they may control dental sensitivity.

The objective of this double blind, randomized and controlled clinical study, was to evaluate the efficacy of potassium nitrate / sodium fluoride (KNO3 / KF) gel associated with LLLT (Low Level Light Therapy) on teeth that were exposed to 35% hydrogen peroxide during 3 weeks of bleaching treatment. Methods: 50 volunteers were evaluated through the split-mouth model, where the hemiarcates were randomized and later allocated in one of the experimental groups: G1 (negative control)- group with no desensitizing treatment, only bleached; G2 (positive control)- group treated with LLLT + placebo gel; G3- group treated with placebo laser application + 5% KNO3 / 2% KF gel; and G4- group treated with LLLT + 5% KNO3 / 2% KF gel.

Group with no desensitizing treatment. Prior to bleaching therapy, a water-soluble placebo gel, with non-active agent will be applied to dental vestibular surfaces. After bleaching therapy, the LASER tip will be positioned in two points (apical and cervical), without light emission (placebo).

Group treated with desensitizing gel before bleaching and after in-office bleaching, the LASER tip will be positioned in two points (apical and cervical), without light emission (placebo).

The group will receive in-office bleaching treatment. Three 15-minute applications of the 35% hydrogen peroxide gel were performed, totaling 45 minutes in each of the 3 sessions, with a 7-day interval.

It will be used the infrared spectrum with wavelength of 808 nm in its active environment AsGaAl, in two points: cervical and apical region of the incisors, canines and premolars.

5% potassium nitrate / 2% sodium fluoride gel will be applied for 10 minutes on the vestibular surface of all pre-bleached dental elements, following the manufacturer's protocol.

The stimulated pain intensity was self reported by the patients with a modified visual analog scale, from 0 to 3, where 0 means "no pain", 1 is "mild pain", 2 is "moderate pain" and 3 is "severe pain". For all groups, the patients evaluated the stimulated pain intensity two times per session: before and after the treatment in the same day. Thus, in total each patient reported the pain intensity 6 times, two times in the first day (1st session), two times in the eighth day (2nd session) and two times in the fifteenth day (3rd session).

Self reported non-stimulated pain intensity was assessed daily, during 21 days, through self-perception questionnaire, answered by the patients from the first tooth bleaching session until one week after the last session. The evaluation was performed by each patient, according to a modified visual analog scale, as follows: 0- no pain, 1 mild pain, 2 - moderate pain and 3 -severe pain

Inclusion Criteria: Absence of active carious lesions; Never undergone bleaching therapy; Good oral hygiene; Do not present hypersensitivity; Do not smoke; Not being pregnant; Presence of at least 28 teeth in oral cavity. Exclusion Criteria: Presence of periodontal disease; Presence of cracks or fractures; Presence of restorations and prostheses; Presence of gastroesophageal dysfunction; Patients with severe internal dental dimming; Presence of periodontal disease; Presence of dentin exposure in anterior and/or posterior teeth.

Reis A, Dalanhol AP, Cunha TS, Kossatz S, Loguercio AD. Assessment of tooth sensitivity using a desensitizer before light-activated bleaching. Oper Dent. 2011 Jan-Feb;36(1):12-7. doi: 10.2341/10-148-CR. Epub 2011 Mar 24.

Moosavi H, Arjmand N, Ahrari F, Zakeri M, Maleknejad F. Effect of low-level laser therapy on tooth sensitivity induced by in-office bleaching. Lasers Med Sci. 2016 May;31(4):713-9. doi: 10.1007/s10103-016-1913-z. Epub 2016 Mar 10.

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