No association between water fluoridation and bone fractures

Abstract

Objective Does water fluoridation have negative effects? This objective was broken down into four sections: fluorosis, bone fracture and bone development effects, cancer and other possible adverse effects.

Data sources See page 37.

Study selection All studies were level C except one which was level B. The mean validity score was only 3.4 out of 8. Only four studies used a prospective design, none used any form of blinding and only one study conducted a baseline examination prior to the introduction of fluoridation.

Data extraction and synthesis A forest plot of all the bone studies was produced showing the measures of effect and the 95% confidence intervals for all those that provided sufficient data to allow calculation.

Results A total of 29 studies met inclusion criteria: 18 studies investigated hip fracture alone. Fourteen found decreased hip fracture associated with increased water fluoride level, of which five were statistically significant (positive association). Thirteen studies, however, showed an increased occurrence of hip fracture with increased water fluoride level, of which four were statistically significant (negative association). The remaining three studies found no association. Three of the 18 studies found the direction of association positive in women but negative in men and one study found a negative effect in women and a positive effect in men. There were no definite patterns of association for any of the fractures

Conclusions The best available evidence on the association of water fluoridation and bone fractures (27 out of 29 studies evidence level C) show no association.

McDonagh M, Whiting P, Bradley M, Cooper J, Sutton A, Chestnutt I, et al. A Systematic Review of Public Water Fluoridation. York: Publications Office, NHS Centre for Reviews and Dissemination, University of York. ISBN 1 900640 16 3; 2000