Fluoridation of the water supply may confer a modest benefit to the dental health of children, a seven-year-study from a research team including the University of Cambridge has concluded. However, the benefits are smaller than shown in previous studies – carried out 50 years ago – when fluoride toothpaste was less widely available in the UK.
The CATFISH study – published today in the Public Health Research – is funded by the National Institute for Health and Social Care Research.
The research is the first contemporary study of fluoridation carried out in the UK since fluoride toothpaste became widely available in the 1970s.
The study also showed it was likely that water fluoridation was a cost-effective way to help reduce some of the £1.7 Billion a year the NHS spends on dental caries.
The study was led by the University of Manchester, with Cambridge University, Kings College London, Salford Royal Foundation Trust and Cumbria Community Dental Service team.
The study assessed the dental health of two cohorts of young children over a six-year period in West Cumbria – where water fluoridation was reintroduced in 2013, and the rest of Cumbria, which remains fluoride free.
In West Cumbria, the younger cohort were born after water fluoridation was introduced (this meant they had the full effect of water fluoridation). The older cohort was aged around five when fluoride was reintroduced into the water supply – which meant they mainly received the benefit for those teeth already in the mouth.
At the end of the study, 1,444 five year olds who were part of the younger cohort and 1,192 eleven year olds who were part of the older cohort had taken part.
Dental teams carried out examinations on the children at regular intervals and took images of their teeth which were blinded to the fluoridation status of each participant to remove bias. They also collected information about the children’s diet, brushing habits and dental attendance.
In the younger cohort, 17.4% of the children in fluoridated areas had decayed, filled or missing milk teeth; the number was 21.4% for children in non-fluoridated areas, amounting to a modest 4% reduction in incidence of caries.
In the older cohort, 19.1% of the children in fluoridated areas had decayed, filled or missing permanent teeth; the number was 21.9% for children in non-fluoridated areas. There was insufficient evidence as to whether water fluoridation prevents decay in older children with a difference of 2.8%.
Over the last 40 years the proportion of children affected by decay has fallen dramatically. But because tooth decay falls disproportionately on more disadvantaged groups, fluoridation should be considered alongside measures targeted at vulnerable populations, the team argue.
Professor Mike Kelly, senior member of the research team from the University of Cambridge, said: “Health inequalities are a feature of all societies, including the UK. The poor dental health of children from the most disadvantaged communities and the excess number of children having general anaesthetics each year still needs to be addressed. We need to continually look at measures which can help prevent the unnecessary burden of pain and suffering.”
Dr Michaela Goodwin from the University of Manchester, senior investigator on the project, said: “While water fluoridation remains cost effective and has demonstrated an improvement in oral health it should be carefully considered along with other options, particularly as the disease becomes concentrated in particular groups.”
“Tooth decay is a non-trivial disease which is why measures to tackle it are so important. The extraction of children’s teeth under general anaesthetic is risky to the child and is the most common reason for children between the ages of 5 and 9 to have a general anaesthetic.”
“Decayed teeth are painful and can impact on sleep patterns, learning, attention and many aspects of general health. But more questions remain, and we hope to follow up on these children in the long term.”
Michaela Goodwin, Richard Emsley, Michael P Kelly, Matt Sutton, Martin Tickle, Tanya Walsh, William Whittaker & Iain A Pretty. Evaluation of water fluoridation scheme in Cumbria: the CATFISH prospective longitudinal cohort study. Public Health Research Volume: 10, Issue: 11, Published in November 2022
Queries: Lucy Lloyd, Communications, Primary Care Unit, University of Cambridge
Infographic by University of Manchester