The findings from the systematic review were that infrequent tooth brushing was statistically associated with periodontitis, but the association was small. In this review, frequency of tooth brushing was used as a proxy for oral hygiene. Of the included studies many different categories of tooth brushing frequency were used. While the authors did not provide a definition for infrequent brushing, it appears they categorised infrequent brushing as once or less per day.

Other difficulties with this systematic review related to the inclusion criteria and confounding. Two studies were included involving participants younger than 22 years, a group in which the prevalence of periodontitis is low.1 Six studies failed to control for confounders, for example, smoking, yet smoking is a well-known risk factor for periodontitis.2

The authors themselves did not define periodontitis and highlighted the lack of a universal definition. In addition, they found many different measures were used for the severity of periodontitis in the included studies, which made synthesising the evidence difficult. In other fields of medicine core outcome sets have been developed; these are standardised sets of outcome measures which should be included in all clinical trials of interventions for a specific health condition.3 Given the range of outcome measures found in this systematic review the development of a core outcome set for periodontitis would be beneficial. Core outcome sets typically include outcome measures of importance to clinicians, researchers and patients.

Periodontitis is not an inevitable part of ageing4 and at present there are no tests available to inform on who might be likely to develop periodontal disease. Therefore it is important to mitigate the possibility of periodontitis by advising patients on how to reduce the risk factors, and the findings from this study support advice for twice daily tooth brushing (Public Health England, 2014).

Practice point

  • Twice daily tooth brushing should continue to be recommended to promote good oral health.