Testing the efficacy of plaque removal of a prototype brush head for a powered toothbrush

The principal aim of the study was to compare the efficacy of a powered toothbrush (PTB) prototype (B) brush head in removing dental plaque to the relative efficacy of a marketed model (A).

A 12-week, 2-group, 2-treatment, double-blind trial of 2, two-brush heads (with the same power unit) recruited 62 volunteers (18-25 years) who were non-clinical university students. After a screening visit, 31 subjects were allocated to each of groups A and B at baseline with stratification according to gender and plaque index. After 48 h of plaque growth, subjects underwent a timed and supervised brushing episode with the allocated PTB (visit 1). Subjects then used the PTBs at home for 12 days before being recalled (visit 2) and asked again to abstain from all oral hygiene measures for 48 h. Supervised brushing was repeated (visit 3) before the subjects were dismissed for a further 10-week, unsupervised period of home use of the PTBs. The sequence of visits (2 and 3) was then repeated at visits 4 and 5.

The sole outcome variable was plaque which was scored at all visits using the modified Quigley & Hein Index (PI) at full mouth (FM), interproximal (IP) and smooth surfaces (S). At visits 1, 3 and 5, the PI was recorded both before and after supervised brushing. There were no significant differences in PI between the brushing groups at baseline, visit 1, visit 2 or visit 5 (2 sided t-test). At visit 3, the prototype achieved significantly lower PIs than the marketed PTB brush head for IP (and FM) surfaces, this difference was most apparent on posterior tooth surfaces. For within-group changes, PIs at visit 2 were significantly lower than those at baseline (paired t-test), an observation which may be attributable to the improved cleaning and 'novelty effect' of a PTB. The PIs at visit 5 were significantly higher than the baseline values (paired t test) and this may be accountable to an element of Hawthorne effect and/or, a fall off in compliance over the entire 12 weeks.

We conclude that this in vivo model is appropriate for testing the efficacy of PTB prototypes but only over a 2-week period, as the inter-group differences were not maintained over the full 12 weeks of the trial.