Effect of Low-level Laser Therapy on Post-bleaching Sensitivity and Color Change

Effect of Low-level Laser Therapy on Post-bleaching Sensitivity and Color Change: a Clinical, Randomized and Double-blind Study

Objective: The objective of this clinical study was to evaluate low-level laser (LLL) therapy in tooth sensitivity and in effecting color change after in-officer bleaching treatment across three weeks of treatment. Methods: Twenty-one volunteers were evaluated through the split-mouth model, so that the right and left maxillary/mandibular quadrants were randomized and allocated to one of two groups: GPLACEBO - the laser tip was positioned without the emission of light (placebo effect) + tooth bleaching with 35% hydrogen peroxide (HP); GLASER - treated with LLL + tooth bleaching with 35% HP. To assess tooth sensitivity, a modified visual analogue scale (VAS) was used after an evaporative stimulus (stimulated pain) and a daily pain questionnaire (unstimulated pain) was also applied. A spectrophotometer was used to measure the color. Three bleaching sessions were performed, with intervals of 7 days. Sensitivity results were tested using Friedman test for intra-group evaluation and Wilcoxon test for inter-group evaluation and ANOVA for color change.

Twenty-one volunteers were evaluated through the split-mouth model, so that the right and left maxillary/mandibular quadrants were randomized and allocated to one of two groups: GPLACEBO - the laser tip was positioned without the emission of light (placebo effect) + tooth bleaching with 35% hydrogen peroxide (HP); GLASER - treated with LLL + tooth bleaching with 35% HP. To assess tooth sensitivity, a modified visual analogue scale (VAS) was used after an evaporative stimulus (stimulated pain) and a daily pain questionnaire (unstimulated pain) was also applied. A spectrophotometer was used to measure the color. Three bleaching sessions were performed, with intervals of 7 days.

Twenty-one volunteers were evaluated through the split-mouth model, so that the right and left maxillary/mandibular quadrants were randomized and allocated to one of two groups: GPLACEBO - the laser tip was positioned without the emission of light (placebo effect) + tooth bleaching with 35% hydrogen peroxide (HP); GLASER - treated with LLL + tooth bleaching with 35% HP.

Only principal investigator performed the clinical research steps. A single evaluator performed the assessment of the dental sensitivity without knowing which treatment was applied. The volunteers evaluated in this study also did not know which hemi-arch received the LLL.

the laser tip was positioned without the emission of light (placebo effect) + tooth bleaching with 35% hydrogen peroxide (HP).

Received Low-lever laser therapy using the infrared spectrum, with a wavelength of 808 nm in its active medium AsGaAl (arsenic-gallium-aluminum), at two points: on the central of cervical and medial regions of incisors, canines and premolars in the corresponding hemi-arch. At each point, 60 J/cm2 was applied during 16 seconds with an irradiance of 3.75 W/cm² using the therapeutic visible infrared device.

Three 15-minute applications of 35% hydrogen peroxide gel (Whiteness HP, FGM®, Joinville, SC, Brazil) were carried out, totaling 45 minutes in each of the four bleaching sessions, with an one-week interval between applications.

Evaporative stimulus (stimulated pain) using air jet from a triple syringe and a daily pain questionnaire (unstimulated pain). Both methods were associated with a modified visual analogue scale was used: 0 (pain absent); 1 (mild pain); 2 (moderate pain) and 3 (severe pain).

Inclusion Criteria: Do not have previous dental sensitivity The canine had to be shade A2 or darker. Exclusion Criteria: Enamel hypoplasia Gingival recession Dentin exposure Visible cracks on buccal enamel Pulpitis