Comparative efficacy of violet light, bleaching gel, or their combination, in in-office bleaching: a systematic review and network meta-analysis

This systematic review and network meta-analysis aimed to determine whether the use of violet light alone (VIOL) or its combination with bleaching gels (BGVIOL) results in superior bleaching efficacy compared to bleaching gel alone (BG). Randomized clinical trials (RCTs) were identified through searches in PubMed, Cochrane Central, LILACS/BBO, SCOPUS, Web of Science, EMBASE, and gray literature sources in March, 2025. Eligible RCTs compared in-office bleaching using BG, or VIOL, or BGVIOL. The Cochrane risk of bias tool was used to evaluate the risk of bias (RoB 2.0) of the eligible RCTs. A random-effects Bayesian mixed treatment comparison model evaluated color change (ΔE*ab and ΔSGU/final SGU), and risk and intensity of tooth sensitivity (TS). Ranking probabilities were evaluated using the surface under the cumulative ranking curve, and the certainty of evidence was appraised following the Grading of Recommendations Assessment, Development, and Evaluation approach. Out of 4,963 records, 17 RCTs were included, 11 of which had a high RoB. Analysis of ΔE*ab revealed significant mean differences (MD) and 95% credibility interval (95%Crl) for the full dataset for BGVIOL vs. BG (MD = 3.13; 95%CrI: 1.33 to 4.97), but not with the subset of data that excluded studies with high RoB (MD = 2.36; 95%CrI: -0.74 to 5.34). Color change in ΔSGU did not differ among groups. VIOL showed the lowest risk and intensity of TS. Color change achieved with BG and BGVIOL was higher than that obtained with VIOL. VIOL yielded lower risk and intensity of TS. The certainty of the evidence supporting these findings is low or very low.