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The impact of stopping or reducing the level of fluoride in public water supplies on dental fluorosis: a systematic review

  • Nor Azlida Mohd Nor EMAIL logo , Barbara L. Chadwick , Damian JJ. Farnell and Ivor G. Chestnutt



The increased availability of fluoride and concern over the impact of fluorosis, have led to guidance suggesting a decrease or cease in the optimal concentration of fluoride in water fluoridation schemes. To date there have been no systematic reviews looking at both impact of fluoride reduction and total cessation. This review aimed to examine the impact of stopping or reducing the level of fluoride in public water supplies on dental fluorosis.


Multiple databases were searched (MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and the Web of Science). Two reviewers independently screened sources, extracted data and assessed study quality. Results were synthesised qualitatively and quantitatively. The main outcome measure was the prevalence of dental fluorosis.


Six studies of cross-sectional design were included. Two studies were scored as evidence level B (moderate) and the remaining four publications were evidence level C (poor). Meta-analysis indicated fluorosis prevalence was significantly decreased following either a reduction in the concentration of fluoride or cessation of adding fluoride to the water supply (OR:6.68; 95% CI:2.48 to 18.00).


The evidence suggests a significant decrease in the prevalence of fluorosis post cessation or reduction in the concentration of fluoride added to the water supply. However, this work demonstrates that when studies are subject to current expectations of methodological and experimental rigour, there is limited evidence with low methodological quality to determine the effect of stopping or reducing the concentration of fluoride in the water supply on dental fluorosis.

Corresponding author: Dr. Nor Azlida Mohd Nor, Department of Community Oral Health & Clinical Prevention, Faculty of Dentistry, University of Malaya, Kuala Lumpur, 50603, Malaysia, E-mail:


Assistance from the subject specialist librarians at Cardiff University is acknowledged gratefully.

  1. Research funding: This work was funded by a scholarship from the Ministry of Education, Malaysia to support PhD studies undertaken by NAMN.

  2. Competing interests: Authors state no conflicts of interest to declare.

  3. Informed consent: Informed consent is not applicable.

  4. Ethical approval: Ethical approval to conduct this study was approved by the Research Ethics Committee, School of Dentistry, Cardiff University (DSREC, 14/17a).


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Supplementary material

The online version of this article offers supplementary material (

Received: 2019-08-02
Accepted: 2020-04-15
Published Online: 2020-06-29
Published in Print: 2020-11-18

© 2020 Nor Azlida Mohd Nor et al., published by De Gruyter, Berlin/Boston

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