What characterizes effective tooth brushing of daily users of powered versus manual toothbrushes?

BACKGROUND: Recent data show comparable deficits in oral cleanliness after tooth brushing in habitual users of powered toothbrushes (PT) and manual toothbrushes (MT). The present analysis explores the origin of these deficits by relating aspects of the observed tooth brushing behaviour to plaque after tooth brushing. METHODS: Users of rotating-oscillating PT (N = 48) and of MT (N = 52) brushed their teeth the best they could while being filmed. Video analyses assessed brushing time, number of sextants brushed sufficiently long (7.5 s per surface; NSBSL), brushing of outer surfaces with closed jaws, and brushing movements. Correlation analyses examined the relationship between these parameters and plaque after brushing (Marginal Plaque Index (MPI); Turesky modification of Quigley Hein Index (TQHI)) and gingivitis (Papillary Bleeding Index (PBI)). RESULTS: In PT users, correlations between behaviour and MPI-scores were significant for the NSBSL (outer surfaces: rho = − 0.249; inner surfaces: rho = − 0.510) and brushing duration (outer surfaces: rho = − 0.399; inner surfaces: rho = − 0.509). In MT users, vertical movements on the outer surfaces were positively related to MPI (rho = 0.299). In contrast, circular movements correlated negatively with MPI in those who brushed all outer sextants sufficiently long (n = 47: rho = − 0.294). In both groups, PBI-scores on the inner surfaces were negatively correlated to NSBSL and brushing duration (rho = − 0.327 − rho = − 0.246). CONCLUSION: NSBSL and brushing duration appear to play an important role for brushing effectiveness and gingival health in PT and MT users. Whether PT users apply brushing movements or not apparently does not affect the result. In MT users, circular movements seem to be more efficient than vertical movements on the outer surfaces. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12903-022-02045-0.