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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

Providing a set of additional fluoride-based treatments at dental appointments for children aged two to three years was no better than health education at preventing tooth decay. A range of public health measures to reduce sugar consumption are also needed.

The treatment involved providing fluoride toothpaste and applying a fluoride varnish to the teeth at each six-monthly appointment for three years.

This large NIHR-funded trial in Northern Ireland found no difference in the number of children developing tooth decay, though children in the treatment arm had fewer teeth showing signs of decay. The estimated cost was £2,093 per child who avoided tooth decay.

The minimal effect reported in this study must be interpreted in light of the population-level benefits achieved with fluoride products to date. In addition, children from the most deprived areas were most likely to experience tooth decay and may be more likely to benefit from fluoride products. These children were under-represented in this study.

Dental practitioners should continue to follow Public Health England guidance and offer all children advice on fluoride-based products. It seems that healthy eating and particularly reductions in sugar consumption might also be part of the solution.

Why was this study needed?

Around a third of 5 year-old children in England, Wales and Northern Ireland have tooth decay (caries) in their primary (baby) teeth. Children with tooth decay experience pain and are more likely to need teeth extracted, at significant cost to the NHS.

Tooth decay happens when mouth bacteria break down dietary sugars, producing acids that erode the tooth enamel. Fluoride toothpastes, mouth rinses and varnishes have been shown to prevent this process.

Guidance from Public Health England recommends that dentists offer all children advice on use of fluoride-based products, dental hygiene and eating healthily, avoiding sugary drinks for example.

However, this advice has improved dental health or social inequalities in outcomes as much as hoped for. So, these researchers were interested in seeing if delivering additional fluoride via varnish and free toothpaste to these children was more effective and cost effective.

What did this study do?

This study assessed whether a comprehensive fluoride intervention provided by dentists was effective at preventing tooth decay in young children. This randomised controlled trial recruited 1248 children aged 2-3 years from 22 NHS dental practices in Northern Ireland. All children were free from tooth decay at study start.

Half of the children were randomly assigned to receive the fluoride-based intervention. This involved applying a fluoride varnish to the teeth and providing a free fluoride toothpaste and toothbrush at every six-month check-up, for three years. They also received dental health education on optimal use of the toothpaste and restricting sugar consumption. The parents in the control group received health education alone.

The study had a large sample size and good follow-up rate, with around 86% of children attending every six-month check-up. Assessors were unaware of group allocation. However, the study had limited scope to understand all behaviours that may influence the results.

What did it find?

  • The fluoride-based intervention was no better than health education alone at preventing caries. Around a third of children in both the intervention (34%) and control groups (39%) developed caries in at least one tooth during the three-year study period (odds ratio 0.81, 95% confidence interval 0.64 to 1.04).
  • Among children who developed caries, the average number of affected tooth surfaces was significantly lower in the intervention group (7.2) than the control group (9.6). An adjusted mean difference of 2.29 fewer surfaces (95% CI 3.96 to 0.63 fewer). Toothache was more common among children who developed caries compared with those who didn’t, but there was no difference in pain rates between study groups.
  • There was little difference between groups in reported adverse effects (7.2% of the intervention group vs 5.9% of controls), and most adverse effects were considered unrelated to treatment. However, 10 children in the intervention group experienced minor effects that were attributed to treatment, including abdominal complaints.
  • The average total cost per child over the three-year study (including the cost of the intervention and any other dental care) was £1,027 in the intervention group and £816 in the control group. The cost of the intervention to prevent one child developing tooth decay was £2,093.
  • Across all participants, children in the most deprived areas were more likely to develop caries than those in less deprived areas (44% vs 28%).

What does current guidance say on this issue?

NICE guidance on oral health promotion for general dental practices (2015) recommends that all patients (or their parents or carers) are given advice during dental examinations, including advice on the use of fluoride, oral hygiene and diet.

Public Health England’s 2014 prevention toolkit for dental health professionals recommends that children up to six years brush their teeth twice daily with fluoride toothpaste. Children aged 3-6 years, or younger if there are dental concerns, should be offered fluoride varnish applied to their teeth twice a year. The frequency and amount of sugary food and drinks should be reduced.

Northern Ireland has an oral health strategy published in 2007 and this recommends that preventing caries in children, particularly among those from disadvantaged backgrounds, should be a key health objective for all Boards and Trusts in Northern Ireland. Northern Ireland does not have a water fluoridation scheme.

What are the implications?

The fluoride-based treatment had a minimal effect on preventing tooth decay that was of questionable clinical benefit. However, the study was conducted against a background of recent population-level improvements in dental health as a result of fluoride-based interventions.

Children from the most disadvantaged areas were under-represented in this study. Practice-based interventions may be unable reach high-risk populations.

Alternative community-based interventions, such as distributing fluoride-containing toothpaste through the post, may have greater potential to reach disadvantaged groups. However, whether such strategies give value for money in preventing tooth decay in young children would need to be addressed.

It seems that two approaches to improving the dental health of children are required, ensuring regular tooth-brushing with fluoride and reducing the intake of sugar and sugary drinks. Fluoride varnish might add little to these actions.


Citation and Funding

Tickle M, O'Neill C, Donaldson M, et al. A randomised controlled trial to measure the effects and costs of a dental caries prevention regime for young children attending primary care dental services: the Northern Ireland Caries Prevention In Practice (NIC-PIP) trial. Health Technol Assess. 2016;20(71):1-96.

This project was funded by the National Institute for Health Research Health Technology Assessment programme (project number 08/14/19).



DHSSPS. Oral Health Strategy for Northern Ireland. Belfast: Department of Health, Social Services and Public Safety; 2007.

NHS Choices. Children’s teeth. London: Department of Health; 2015.

NHS Digital. Child Dental Health Survey 2013, England, Wales and Northern Ireland. Leeds: NHS Digital; 2015.

NICE. Oral health promotion for general dental practices. London: National Institute for Health and Care Excellence; 2015.

Public Health England. Delivering better oral health: an evidence-based toolkit for prevention. London: Public Health England; 2014.

Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre


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The toothpaste provided in this study had a fluoride concentration of 1,450 parts per million (ppm). Toothpaste containing between 1,350 and 1,500 ppm of fluoride is thought to be most effective at preventing tooth decay. Public Health England recommends that children under 3 years brush their teeth twice daily using a smear of toothpaste containing at least 1000 ppm of fluoride; children aged three to six years should use a pea-sized amount. Children above 6 years through to adulthood should use toothpaste with a fluoride concentration of 1,350 to 1,500 ppm.

The varnish used in this study contained 22,600 ppm of sodium fluoride, or 2.2%, which is the government recommended concentration for all children.


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