To ask Her Majesty’s Government what assessment they have made of the statement in the 2015 systematic Cochrane review Water fluoridation for the prevention of dental caries that the authors’ confidence in evaluating fluoridation’s effectiveness was limited by there being "very little contemporary evidence, meeting the review’s inclusion criteria", and by "the high risk of bias within the studies and, importantly, the applicability of the evidence to current lifestyles".
The results of the 2015 ‘Cochrane Review’ Water fluoridation for the prevention of dental caries’, Iheozor-Ejiofor et al, Feb 2015 are broadly consistent with those from other systematic reviews conducted over the past 15 years in concluding that this public health measure is, as the Cochrane authors state, “effective at reducing levels of tooth decay in both children’s baby and permanent teeth.”
The Cochrane review used specific and relatively narrow criteria requiring that studies include baseline measures of dental caries in two communities, one of which then introduced fluoridation within three years. This approach had the consequence of excluding numerous studies conducted over the past 25 years which compared dental caries levels in fluoridated and non-fluoridated communities. The Cochrane reviewers acknowledge in their report that there may be concerns regarding the exclusion of these studies from their review.
The Cochrane review analysed studies conducted in different ways at different times in different places, finding consistent reductions in levels of dental caries following the introduction of fluoridation. The term ‘bias’ used in the Cochrane review has a specific scientific meaning relating to controlling for other factors such as dietary habits that might have affected the levels of dental caries in the populations studied. The reviewers recognise that this bias “may occur in either direction”.
Relatively recent studies which did not meet the reviewer’s specific inclusion criteria have continued to find substantial dental benefits of water fluoridation. Public Health England’s (PHE) recent Monitoring Report (2014) looked at fluoridated and non-fluoridated communities in England and found that communities served by water fluoridation schemes continue to show lower levels of tooth decay.
A copy of PHE’s report is attached.