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

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.

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.

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.

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.

ClinicalTrials.gov, NCT06358482.