Bleaching performed at-home while under the supervision of a dentist provides greater color alteration compared with whitening strips when evaluated with a spectrophotometer, although the color alteration was undetectable by unaided human eyes.
A systematic review and meta-analysis were performed to answer the following research question: Does the use of whitening strips (WS) lead to an equivalent color change compared with supervised dental bleaching in patients with permanent dentition?
A search was performed on August 10, 2017 (updated on March 22, 2019), in PubMed, the Brazilian Library in Dentistry, Latin American and Caribbean Health Sciences Literature database, Cochrane Library, Scopus, Web of Science, and grey literature, without restrictions regarding date or language. Abstracts from the International Association for Dental Research, unpublished and ongoing trial registries, dissertations, and theses were also searched. Only randomized clinical trials (parallel or split mouth) in patients with permanent dentition that compared WS with dentist-supervised dental bleaching performed at-home (AH) or in-office (IO) were included. The risk of bias (RoB) was evaluated using the Cochrane Collaboration tool. A meta-analysis with subgroup analysis (low and high peroxide concentration) was conducted for color change ΔE* (spectrophotometer) and ΔSGU (shade guide units), risk and intensity of tooth sensitivity (TS), gingival irritation (GI), and patient satisfaction using a random effects model. Heterogeneity was assessed with the Cochran's Q test and I2 statistics. GRADE (Grading of Recommendations, Assessment, Development and Evaluation) was used to assess the quality of the evidence.
After the removal of duplicates, followed by title and abstract screening, 20 studies remained. Only two studies were considered to have a low RoB; 11 had a high RoB, and seven had an unclear RoB. For WS versus IO, data were not available for the meta-analysis. For WS versus AH bleaching, a significant difference in ΔE* favoring the AH group was observed (standardized mean difference [SMD] = −0.50, 95% confidence interval [CI] −0.79 to −0.21), but the risk (risk ratio = 0.78, 95% CI 0.65 to 0.93) and intensity of TS (SMD = −0.30, 95% CI −0.56 to −0.04) were lower in the WS group. Color change in ΔSGU, risk and intensity of GI, and patient satisfaction were not significantly different between groups (p>0.20). The quality of evidence for ΔE*, risk and intensity of TS, and intensity of GI were graded as moderate.
Although the risk and intensity of TS were lower in the WS group, dentist-supervised at-home bleaching led to a better color change when measured with a spectrophotometer, although the color alteration was undetectable by unaided human eyes.