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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.

Dentists invite most people for dental check-ups every six months. Despite being common practice in the UK and many other countries, this interval is based on low quality evidence. 

The results of a large trial across the UK (INTERVAL) did not support such frequent dental appointments.  

It found that the 30% people at low risk of oral disease could be seen once every two years without detriment to their oral health. Over a four-year period, more frequent check-ups had no added benefit. The research concluded that a check-up interval based on each person’s individual risk of oral disease did not adversely affect their oral health. This approach was acceptable to patients and dentists and could save money.

What’s the issue?

Routine NHS dental check-ups include a clinical examination, monitoring of oral health, and advice. Regular check-ups aim to detect the early signs of dental disease such as decay and gum disease. 

NICE guidelines recommend that dentists and patients agree on a suitable interval between check-ups. This interval ranges from every three months to every two years for adults. Most dentists encourage people to have check-ups every six months. But these recommendations and customs are based on low quality evidence. 

There is a growing need to reform dental services and prioritise the prevention of oral health problems. The risk of developing oral disease varies between individuals, and resources should therefore target those at higher risk. COVID-19 has prevented many from accessing dental care, and made these needs more urgent. In work carried out before the pandemic, researchers sought to update the evidence behind current guidelines. They wanted to identify the check-up interval that would best maintain oral health while offering value for money. 

What’s new?

The four-year INTERVAL trial was a randomised controlled trial. It included 2,372 adults from dental practices across the UK. Approximately 70% completed all aspects of the trial and attended the follow-up appointment four years later. 

Participants were randomly allocated to one of three groups:

  • fixed check-ups every six months (high- and low-risk participants) 
  • check-up intervals based on each person’s risk of oral disease (high- and low-risk participants) 
  • fixed check-ups every two years (only for participants who were considered to be low-risk by their dentist).

Oral health was determined in this study by measuring the extent to which gums bled when probed. This indicates inflammation, and early gum disease. The researchers also looked at the extent of tooth decay, tartar build-up on teeth, the need for preventive treatment (such as removing plaque and tartar), the need for intervention (such as filling cavities), and dentists’ attitudes towards recall intervals. They asked patients to describe their anxiety, satisfaction with care, knowledge of oral health, attitudes and behaviours. 

The results suggest there are no dental health benefits to 6-monthly check-ups compared to risk-based intervals or 2-yearly check-ups (for people at low-risk). There was no difference in bleeding gums or in oral health-related quality of life. Nor did the evidence show any differences in the other clinical outcomes.  

Overall, participants were satisfied with the dental services they received and were not anxious about their dental health. They had good knowledge about how to brush, though few participants knew to spit without rinsing after brushing. 

The research included an analysis of costs to the NHS and to patients, and explored peoples’ willingness to pay for dental appointments. Three different analyses looked at which treatment interval offered the best value for money, while maximising general health-related quality of life, overall benefit to society, and benefits to dental health.

The results of the economic evaluations were mixed.  The benefits to general health were uncertain, possibly because the measure used may not have been sensitive enough to pick up differences in dental health. However, with respect both to general health and dental health, the 2-year recall period (for low-risk patients) is likely to be the most cost-effective approach because of the potential cost savings from fewer appointments.

With respect to society, there were benefits to six-monthly check-ups because most people valued and were happy to pay for them. 

The researchers conclude that a risk-based interval personalised to each person could save money without having a negative impact on oral health.

Why is this important?

The findings suggest that the custom of providing six-monthly check-ups, regardless of the person’s risk of developing dental disease, does not improve oral health. 

The results of this study can inform clinical guidelines to aid decision-making on check-up frequency by dentists. A personalised check-up frequency, based on individual risk, could be a more efficient use of NHS resources.

The results of this study are reflected in the updated Cochrane Review, Recall intervals for oral health in primary care patients.

What’s next?

The evidence from this study and the related Cochrane Review could be integrated into clinical guidance for dentists. Moving towards a personalised, variable recall strategy will need close cooperation between policymakers, clinicians, and patients. 

People valued check-ups every six months in this study, and said they were willing to pay for them. However, the economic analyses were based on surveys of regular attenders who may value frequent check-ups more than other people. The researchers say more information is needed on why check-ups are so valued – perhaps due to it being an established routine, a recommendation, or other reasons. They say careful messaging may help people to understand that personalised, risk-based intervals between appointments are safe.

The researchers would like to develop risk assessment tools to help dentists choose recall intervals, based on their patients’ likelihood of developing dental disease. 

This study included adults only. More research is needed before any change is made to recall intervals for younger people.

You may be interested to read

The full paper: Clarkson JE and others. Risk-based, 6-monthly and 24-monthly dental check-ups for adults: the INTERVAL three-arm RCT. Health Technol Assess. 2020;24

The results of the clinical outcomes are summarised here: Clarkson JE and others. Examining the effectiveness of different dental recall strategies on maintenance of optimum oral health: the INTERVAL dental recalls randomised controlled trial. Br Dent J. 2021;230:236–243

The protocol for this trial, as described in another paper: Clarkson JE and others. INTERVAL (Investigation of NICE Technologies for Enabling Risk-Variable-Adjusted-Length) dental recalls trial: a multicentre randomised controlled trial investigating the best dental recall interval for optimum, cost-effective maintenance of oral health in dentate adults attending dental primary care. BMC Oral Health 2018;18:135

The recent Cochrane Database Systematic Review, which included the results of this study, also concluded that there was little to no difference in tooth decay, gum disease and well-being between 6-monthly and risk-based check-ups in adults: Fee PA and others. Recall intervals for oral health in primary care patients. Cochrane Database Syst Rev. 2020;10:CD004346

An infographic overviewing how to perform a risk assessment and allocate an appropriate risk-based recall


Funding: This research was funded by the NIHR Health Technology Assessment programme.

Conflicts of Interest: One author has received fees from toothpaste manufacturers. 

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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