Evaluation of the Whitening Efficacy and Enamel Surface Roughness of Commercially Available Household Products and Preparations Promoted for Do-It-Yourself (DIY) Tooth Whitening: An In Vitro Study

Aim: The increasing popularity of do-it-yourself (DIY) tooth whitening using natural products has raised concerns regarding their effectiveness and potential adverse effects on enamel. This in vitro study aimed to compare the colour changes produced by selected commercially available household products and preparations promoted for DIY tooth whitening and to evaluate their influence on enamel surface roughness. Materials and Methods: Thirty extracted human teeth were stained with coffee and black tea and randomly assigned to five groups (n = 6): activated charcoal, baking soda, coconut oil, turmeric, and a lemon juice–baking soda mixture. Specimens were brushed twice daily for 14 days using an electric toothbrush. Tooth colour was measured at baseline (T0), after 7 days (T1), and after 14 days (T2) using a digital spectrophotometer (CIE Lab* system). Colour change (ΔE), bleaching index, and enamel surface roughness (Ra) were assessed. Data were analysed using ANOVA with Tukey post hoc tests and Pearson correlation analysis (p < 0.05). Results: All tested agents produced perceptible colour changes (ΔE > 3.3) after 7 and 14 days. Significant differences in colour parameters and the bleaching index were observed among groups over time (p ≤ 0.001). Activated charcoal produced the largest overall colour change; however, none of the tested agents fulfilled the directional criterion for true whitening (increased L* with decreased b*). Enamel surface roughness increased significantly over time; however, no statistically significant agent-specific effect was demonstrated. Likewise, no statistically significant correlations were found between post-treatment surface roughness and the evaluated colour parameters or the bleaching index.