Electric vs Manual Toothbrushing Effects on QLF-Assessed Plaque in Smokers and Non-Smokers: A 24-Week RCT

BACKGROUND: Electric toothbrushes are known to outperform manual devices in plaque removal, yet most comparative trials rely on conventional examiner-based indices and none have evaluated efficacy across smoking profiles using objective fluorescence-based measurement. METHODS: This 24-week, 2-arm, parallel-group randomized controlled trial compared an oscillating-rotating electric toothbrush (Oral-B iO 6) with a manual toothbrush in 126 adults aged 18 to 50 years attending a dental clinic for routine scaling and polishing. Current smokers and never-smokers were enrolled to allow prespecified subgroup analysis by smoking status. Dental plaque accumulation was quantified using quantitative light-induced fluorescence (QLF) technology. The primary endpoint was ΔR30 (percentage of tooth surface with fluorescence increase ≥30%, reflecting total mature plaque); ΔR120 (fluorescence increase ≥120%, reflecting thick plaque and calculus-like deposits) was the secondary endpoint. The primary analysis used analysis of covariance adjusting for baseline plaque levels, treatment arm, smoking status, and their interaction. RESULTS: Use of the electric toothbrush was associated with significantly lower ΔR30 at 24 weeks compared with manual brushing (β = -1.84, 95% CI [-3.27, -0.41], p = .012), an effect that remained robust after adjustment for age, sex, and habitual oral hygiene behaviours. Baseline plaque level was the strongest predictor of follow-up values in both outcome models. No significant treatment effect was observed for ΔR120 (β = -0.77, 95% CI [-1.71, 0.18], p = .112). Subgroup analyses showed significant between-arm differences on both outcomes among never-smokers; among smokers, differences were directionally consistent but did not reach statistical significance, and the treatment-by-smoking interaction was not statistically significant. CONCLUSIONS: Oscillating-rotating electric toothbrushing produced significantly lower plaque accumulation than manual brushing over 24 weeks, as indexed by QLF-derived ΔR30. These findings support the potential advantage of oscillating-rotating powered toothbrushes for reducing plaque accumulation in adult patients and further support the utility of QLF as a precise and reproducible outcome measure for toothbrush efficacy trials. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT06358482.