Objectives: The purpose of this randomized double-blinded clinical trial was to test the efficacy and tooth sensitivity promoted by the use of an in-office 15% H₂O₂ bleaching agent containing nanoparticles of TiO_N photocatalyzed with LED/laser light (HP15) and a control of 35% H₂O₂ (HP35). Methods: Forty healthy volunteers, both sexes, aged 18 to 25 yr, were randomly distributed in 2 groups: HP15 ( n = 20) was treated in 3 sessions of 48 min each, and HP35 ( n = 20) was treated in 3 sessions of 45 min each. The efficacy (E) was evaluated by ΔE values measured via reflectance spectroscopy. The tooth sensitivity (S) was analyzed by visual analog scale (low, average, high, very high). The absolute risk reduction and the number needed to treat index were calculated. The data were analyzed by mixed repeated measures analysis of variance with Bonferroni-correction t test ( α = 0.05). Results: For the efficacy, significant differences were found for number of bleaching sessions ( p = .0001; [ ] = 0.73 and π = 1.000) and for the interaction of number of sessions and bleaching protocols ( p = .0001; [ ] = 0.319 and π = 1.000. The tooth sensitivity level showed significant differences only between the bleaching protocols. Absolute risk reduction calculated was 52% and number needed to treat, 1.92. Conclusions: The bleaching agent with the lower concentration (HP15) promoted lower levels of tooth sensitivity and presented greater efficacy compared to the control (HP35) in patients between 18 and 25 yr old. The limitation of short-term evaluation did not provide information about the longevity of the tooth bleaching (Brazilian Clinical Trials Registry Re Bec no. U1111-1150-4466).

SUMMARY: Objective: The aim of this blinded and randomized clinical trial was to compare two application protocols (one 36-minute application vs three 12-minute applications). We then assessed the effectiveness of the bleaching and any increase in sensitivity that was induced by bleaching via a split-mouth design. Methods and Materials: Thirty patients were treated. One group had a half arch of teeth treated with a traditional application protocol (group A: 3 × 12 minutes for two sessions). The other received an abbreviated protocol (group B: 1 × 36 minutes over two sessions). Two sessions were appointed with a two-day interval between them. The tooth color was registered at each session, as well as one week and one month after completing the treatment via a spectrophotometer. This measured L*, a*, and b*. This was also evaluated subjectively using the VITA classical A1-D4 guide and VITA Bleachedguide 3D-MASTER. Tooth sensitivity was registered according to the visual analogue scale (VAS) scale. Tooth color variation and sensitivity were compared between groups. Results: Both treatments changed tooth color vs baseline. The ΔE* = 5.71 ± 2.62 in group A, and ΔE* = 4.93 ± 2.09 in group B one month after completing the bleaching (p=0.20). No statistical differences were seen via subjective evaluations. There were no differences in tooth sensitivity between the groups. The absolute risk of sensitivity reported for both groups was 6.25% (p=0.298). The intensity by VAS was mild (p=1.00). Conclusions: We used hydrogen peroxide (6%) that was light activated with a hybrid LED/laser and two different protocols (one 36-minute application vs three 12-minute applications each for two sessions). These approaches were equally effective. There were no differences in absolute risk of sensitivity; both groups reported mild sensitivity.