An investigation into the effect of three months' clinical wear on toothbrush efficacy: results from two independent studies

Abstract

Objective: Limited evidence has suggested that a worn toothbrush may be significantly less effective than a new brush with respect to plaque removal. Two independent studies, one with a manual toothbrush and one with a powered toothbrush, were undertaken to compared the ability of these toothbrushes as new and after three months' use to remove plaque.

Methodology: Subjects from a general population were given either an Oral-B CrossAction manual toothbrush (Study 1) or a Braun Oral-B Battery (D4) toothbrush (Study 2). They were instructed to use their respective toothbrushes twice per day for a period of three months. After this time, those subjects meeting the studies' respective inclusion criteria entered the single-use, cross-over phase of the two studies. Both studies involved disclosing the teeth prior to measuring plaque. In Study 1, plaque was recorded using the Proximal Marginal Plaque Index and subjects brushed for one minute, by random assignment, with either a new or a worn toothbrush. In Study 2, plaque was measured using the Modified Quigley-Hein Plaque Index and subjects brushed for two minutes with either new or used brush heads, by random assignment. After a period of approximately one week, subjects returned to the test facilities and brushed with the alternate brush.

Results: Study 1 showed that both the new and the worn CrossAction toothbrushes significantly reduced plaque scores (p < 0.0001). A comparison of the two toothbrushes revealed no significant difference for whole-mouth plaque scores; however, at approximal sites the new toothbrush was significantly more effective than the worn brush (p = 0.033). In Study 2, as in Study 1, brushing with either a new or a worn brush head significantly reduced plaque scores (p < 0.0001). A comparison of the efficacies of the new and worn D4 toothbrushes revealed a non-significant tendency for the new brush head to remove more plaque than the worn brush head. However, when plaque removal was assessed for subjects using brush heads with the most extreme wear, i.e., scores of 3 or 4 (n = 15), a significant difference (p < 0.05) between new and worn brush heads was observed for the whole-mouth and approximal surfaces.

Conclusion: The results from these two studies provide further data in support of the hypothesis that a worn toothbrush is less efficient with respect to plaque removal than a new brush. Patients should therefore be encouraged to replace their toothbrush regularly before bristle wear becomes excessive.