J Contemp Dent Pract. 2026 Feb 1;27(2):148-155. doi: 10.5005/jp-journals-10024-4029.
ABSTRACT
AIM: To evaluate the effect of over-the-counter (OTC) whitening products on postbleaching enamel surface roughness and the ability to recover the postbleaching shade after a standardized staining challenge under in vitro conditions.
MATERIALS AND METHODS: This experimental, longitudinal in vitro study included 40 human enamel specimens. Specimens were subjected to bleaching with 35% hydrogen peroxide (HP) and then immersed in a purple-corn beverage at 37°C for 30 minutes every 24 hour for 28 days; the beverage was renewed daily. Specimens were randomly assigned to four equal groups (n = 10) according to the OTC treatment: Group I, distilled water (control); group II, whitening strips (WS); group III, whitening mouthwash (WM); and group IV, WS + WM. Shade recovery was assessed using the CIEDE2000 color difference (ΔE00) relative to the postbleaching reference shade, and surface roughness (Ra) was measured with a contact profilometer at baseline (post-staining, pre-OTC) and after the assigned OTC regimen. Statistical analyses included paired Student’s t-tests, MANOVA, and one-way between-groups ANOVA (p < 0.05).
RESULTS: At baseline, no between-group differences were observed for Ra (p = 0.893) or ΔE00 (p = 0.304). After exposure, Ra increased significantly compared with control in WS (p = 0.026), WM (p = 0.002), and WS + WM (p = 0.025), with no differences among the three OTC regimens (p > 0.05). Within groups, Ra increased in WS (+0.83 μm; p < 0.001), WM (+1.18 μm; p = 0.001), and WS + WM (+0.72 μm; p = 0.005), but not in the control (p = 0.532). For ΔE00, there were between-group differences (p < 0.001): WS + WM yielded the lowest values and differed from control, WS, and WM (all p < 0.05), while WS and WM did not differ from each other (p > 0.05). Within groups, ΔE00 decreased in WS (-14.62; p < 0.001), WM (-16.47; p < 0.001), and WS + WM (-21.19; p < 0.001), with no change in the control (p = 0.292). A global multivariate effect of OTC whitening was detected [Wilks’ Λ, p < 0.001; partial η² (ηp²) = 0.753], with a very large effect size for ΔE00 (ηp² = 0.934) and a moderate one for Ra (ηp² = 0.326).
CONCLUSION: Under in vitro conditions, OTC whitening regimens increased enamel surface roughness and reduced color difference, with a larger effect on ΔE00 than on Ra. The combined regimen of strips and mouthwash produced the greatest reduction in ΔE00, while Ra did not differ among OTC protocols. Longer-term randomized clinical trials are needed to determine the clinical relevance of these findings.
CLINICAL SIGNIFICANCE: After professional bleaching, OTC WS, WM, or both may improve color recovery, but they may also increase enamel surface roughness. Clinicians should advise patients about this esthetic-surface trade-off and recommend judicious use. How to cite this article: Llancari-Alonzo R, Manrique-Guzmán J, Manrique-Chávez J, et al. Effect of Over-the-counter Whitening Products on Postbleaching Enamel Surface Roughness and Shade Recovery: An In Vitro Study. J Contemp Dent Pract 2026;27(2):148-155.
PMID:42145163 | DOI:10.5005/jp-journals-10024-4029
