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Objective To answer the question: “Does the peroxide gel application regimen (single application vs. renewal) influence the efficacy and the tooth sensitivity outcomes of in‐office tooth bleaching?” Methods The search was done in Pubmed, Cochrane, LILACS, Scopus, Web of Science, and EMBASE in February 2021 (updated in July 2021). Randomized clinical trials (RCT) comparing the single application vs. the renewal protocols of HP were included. The meta‐analyses were performed for the objective (ΔEab), subjective (ΔSGU) color changes, and absolute risk of tooth sensitivity (TS). Heterogeneity was evaluated using Q test (I2). Cochrane Collaboration tool assessed the risk of bias (RoB). The GRADE evaluated the certainty of evidence. Results Five RCT studies remained. Two studies showed high RoB, and three presented some concerns. No significant differences were observed between the protocols in terms of the ΔEab, ΔSGU, and TS. ΔEab exhibited substantial heterogeneity (I2 = 87%), while ΔSGU (I2 = 60%) and the TS (I2 = 62%) presented a moderate one. The certainty of evidence was considered low or very low, depending on the variable response and the evaluation time. Conclusion The application regimen (single vs. renewal of HP) did not impact color change or the absolute risk of TS. Clinical significance The renewal of bleaching gel during the in‐office appointment may not be necessary. However, there is at least a low certainty of evidence. Because of this, further randomized clinical trials with appropriate methodology on this topic are encouraged.

Objective: This study evaluated the efficacy and tooth sensitivity of bleaching with the novel violet LED light used in different in-office approaches. Clinical Considerations: Three patients were submitted to anamnesis, clinical and radiographic exams and to different bleaching protocols and materials. Case report I: Violet LED light was applied in 20 irradiations of 1 minute at 30-s intervals without the use of peroxide agents. After eight appointments with 4 or 7-day intervals, no tooth sensitivity (TS) was reported and color changed from A2 to A1 and from B3 to A2 in upper central incisor (tooth 11) and upper canine (tooth 13), respectively. Case report II: The same protocol established for violet LED light application was used and associated with 37% carbamide peroxide in three appointments at intervals of 7 days. Color changed from A3,5 to B2 (tooth 13), and provoked TS was reported. Case report III: 35% hydrogen peroxide was associated with the same violet LED regimen and number of sessions. Although spontaneous TS was reported in low levels, color changed from A2 to B1 (tooth 11) and from A3 to B1 (tooth 13). Conclusion: Although the three treatments promoted different bleaching responses, in vitro and in vivo investigations of the violet LED protocols are still necessary. In addition, the fact that the sensitivity levels obtained are compatible with conventional bleaching treatments demonstrated that violet LED light is possibly adequate for clinical use. Clinical Significance: Bleaching of vital teeth with violet LED with or without peroxide agents exhibited acceptable clinical results and low sensitivity responses.

Bovine dental enamel blocks were obtained and artificially stained with the extrinsic pigments (n=50): SK, CF, RW or control (C). Afterwards, specimens were treated with the following bleaching protocols: LED, LED/CP, CP, LED/HP and HP. Color change (Delta E) was measured considering after staining (T0), 24 hours elapsed from bleaching (TB) and 7 days after treatments (T7) times by means of digital spectrophotometry. Data was tested by two-way ANOVA and Tukey's Test. Enamel's surface morphology after treatments was analysed under scanning electron microscope (SEM). Type of staining and bleaching protocols significantly affected bleaching outcomes (p<0.001). Regardless of the extrinsic pigment, LED promoted statistically greater Delta E for stained groups in comparison to C (p<0,05). LED alone promoted clinical perceptible Delta E, but in less extent than for gels. LED/CP Delta E was significanty greater than CP's for CF, RW and C (p<0.05). Equal Delta E was found for LED/CP and HP for all pigments (p>0.05), except for CF (p=0,020). Only CF led LED/HP Delta E to be significantly higher than HP (p=0.012). Seven days elapsed from bleaching, outcomes were mantained. SEM images revealed that topography of enamel bleached with gels suffered alterations, but this was not exacerbated by LED irradiation.