Commentary

This systematic review assessed randomised controlled trials of the following types of power toothbrushes (compared to manual toothbrushes): side-to-side, counter-oscillation, rotation-oscillation, circular, ionic and ultrasonic.

The authors clearly state at the outset of their discussion that:

  • ‘The selection of one's toothbrush is largely a matter of personal preference, affordability, availability and professional recommendation.’

  • ‘There is overwhelming evidence that toothbrushing reduces gingivitis.’1

  • ‘These benefits occur whether the brush is manual or powered...’

All that said, the results of the very well done systematic review indicate that power toothbrushes, when compared to manual toothbrushes,

A. Reduce plaque by:

  • 11% if used for less than three months (40 trials)

  • 21% if used for greater than three months (14 trials)

B. Reduce gingivitis by:

  • 6% if used for less than three months (44 trials)

  • 11% if used for greater than three months (16 trials)

Of particular interest, and also consternation, is that only one powered toothbrush – rotating oscillating – consistently demonstrated significant improvement. All other power toothbrushes showed some statistical differences at some time points, but inconsistent differences at other time points.

One might expect manufacturers of power toothbrushes to create pristine clinical trials that support the superiority of their product. However, the quality of the trials was variable. Five trials were at high risk of bias, five at low risk of bias, and for the remaining 46 trials the risk of bias was unclear. Further, many trials used a split mouth design, which undermines generalisability, and many trials did not provide the following, which again raises concerns about validity:

  • Power calculations

  • Intention-to-treat analysis

  • Evidence of adherence to CONSORT statement (http://www.consort-statement.org/) guidelines, or adherence to recommendations for toothbrush trials.2

In spite of these concerns, the systematic review's authors found no evidence of publication bias. Further, they found no difference in outcomes based on sensitivity analysis of funding source for those trials with low risk of bias.

The sense one comes to is that power toothbrushes, as a class of toothbrush, offer a statistically significant reduction in plaque and gingivitis. And, when used for more than three months, this reduction may also be clinically significant.

Clinical significance is best understood from both the clinician's and patient's perspective. If plaque and gingivitis are not a significant clinical problem for a patient, then spending twice to ten-times the cost of a manual toothbrush to purchase a power toothbrush may be a step too far. On the other hand, if a patient has just invested $5,000, $10,000 or $20,000 for restorative or aesthetic dentistry, then a $25 to $100 investment in a power toothbrush may be inexpensive insurance against plaque and gingivitis.

Finally, it is worth considering potential changes in methodologies and outcomes, given the 11-year time lapse from the first Cochrane review of power toothbrushes,3 and the current review. Over this period the number of subjects engaged in these toothbrush trials nearly doubled from approximately 2,500 to 4,500, and the types of power toothbrushes increased by one (ionic).

However, the critiques of the individual trials remain essentially the same, as does the outcome – power toothbrushes appear to be more effective than manual – with the rotation-oscillation appearing to be more consistently effective than the other power toothbrushes.4 This suggests that the Cochrane Oral Health Group may want to consider using methods for assessing need for a new review5,6 as an alternate to the stated two-year time frame.7 This would simultaneously conserve resources and provide mini-updates. An oral health example of this was recently provided with good effect in examining the need for further systematic reviews comparing glass-ionomer and resin sealants.8