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Scale and polish to prevent oral and dental disease - what is the evidence?

Posted by Beatriz Goulao (Admin) Sep 18, 2021

This post is adapted from a post originally available in the Evidently Cochrane website

Scale and polishes and education are used as the main strategies to prevent gum disease in the National Health Service (NHS). However, there was no strong evidence to support they work before the IQuaD study was done. This blog post focuses on describing the largest trial investigating the effect of scale and polish and/or education in preventing bleeding gums. IQuaD was conducted by our team that hosts the GUIDE oral and dental health platform. 

The IQuaD Trial: investigating scale and polish

 IQuaD – Improving the Quality of Dentistry - was a ground-breaking trial: it was testing whether 6-monthly scale and polish improved gums’ health compared with yearly scale and polish or none over three years on regular attenders to the dentist with healthy gums. To my surprise as a dental patient, this was the largest trial ever to test this question. Even though this was such an engrained health behaviour in the UK and worldwide, there was actually no evidence behind the idea that a scale and polish every six months helps keep your gums healthy. 

How do we measure gum health?

We collected data on bleeding on probing, calculus (tartar) and pocket depth as indicators of your gums’ health. Initially I was surprised about this. I thought bleeding gums were just a result of brushing teeth too hard. I did not realise they were indicative of gum inflammation and could lead to more serious disease and even tooth loss. This is the thing about gum disease: it is silent and it can secretly deteriorate until it is found. IQuaD also tested whether personalised oral hygiene advice improved gums’ health or patients’ self-confidence in their ability to brush or floss compared with routine advice (both given by the dentist or hygienist).

No evidence of a difference in bleeding gums

The results are now out and so is the Cochrane Review (a review including all the best evidence available related to the effectiveness of scale and polish) that includes them. To summarise IQuaD: there is no evidence of a difference in bleeding between 6-monthly, 12-monthly or no scale and polish over three years in healthy adults that attend NHS dentists in the UK. The differences found were very small and we were confident they excluded the possibility of a clinically meaningful difference between the groups. The same was observed for personalised versus routine advice in bleeding and self-confidence on the ability to brush and floss. The Cochrane Review supports these findings.

We prepared an infographic (below) to disseminate the results to trial participants and dentists with the support from the public and patient’s involvement group at the Health Services Research Unit. The group’s main concern when introducing these results to the public was clear: scale and polish might not improve your gum health, but we should make it clear that patients still need to go back and get check-ups done. Should we?

We did not find any benefit of being allocated scale and polish twice a year or once a year compared with no scale and polish for three years. We did not find any benefit of being allocated personalised advice over usual advice for three years.


A more complicated story?

We were not just interested in the clinical effectiveness of scale and polish; we also looked at how much people valued the treatment and why. We conducted a survey asking people’s preferences and willingness to pay for different dental packages. The work, led by Dr Dwayne Boyers, is described here. A brief summary is: the general population value scale and polish and personalised education. Responders to the survey showed a willingness to pay more per year to have their teeth look and feel very clean (compared with look and feel very unclean) than their willingness to pay to never have bleeding gums (compared with having bleeding gums very often). This shows the general population attaches a greater value to shifts in their aesthetic outcomes compared to changes in bleeding gums.

The results can lead to a more complicated story. If people feel better after having a scale and polish and it contributes to their confidence and their appearance, should we be including it as part of the NHS even though it does not improve gum health?

If you would like to discuss these results, please head to our challenges and select the one the you think is the most appropriate to share your ideas and thoughts. 

Bottom line

Unfortunately, many treatments provided in primary care dentistry have been based in anecdotes and weak evidence. With IQuaD and Cochrane Reviews on topics such as scale and polish and dental check-ups, we hope to change that and contribute to an evidence-base practice of dentistry. We need good quality evidence to support the treatment we get in our dental practices and how the NHS funds are spent. More research is needed on how to prevent gum disease: even though its cornerstones (scale and polish and oral hygiene advice) have been questioned, there is still a lot to be done. Different types of education or targeting specific groups could lead to different conclusions. This is why your help, as part of the GUIDE oral and dental health community, is so important!

Funding note

IQuaD was funded by the NIHR Health Technology Assessment (HTA) programme. The views expressed are those of the  author(s) and not necessarily those of the NHS, the NIHR  or the Department of Health.

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Comments (3)

Irene Soulsby says... Sep 18, 2021

When I was younger, I thought that "going to the dentist" was just about my teeth.  I realise now that it's more complicated than that!  I hadn't heard about "willingness to pay" until fairly recently and wondered if others had come across this term before, perhaps they would like to know what "willingness to pay" is.

Gillian Nevin says... Sep 24, 2021

The cosmetic appearance of white teeth can be seen as achievable by a scale and polish by some patients - therefore they are happy to pay for a look and feeling of clean. It's harder to educate that the work of healthy teeth and gums isn't down to one appointment but a wider regime of oral care

Gavin Paterson says... Oct 21, 2021

My experience of scale and polish is that its use has declined. My dentist stopped offering the polish on the NHS four years ago, which was a shame in that sense that I liked the feeling of smooth teeth afterwards. I  didn't receive a scale when I went for a check up a fortnight ago, perhaps because he took x-rays instead. I can't say I am overly troubled by this as my main concern is the check-up itself.

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