Topic

NNT - tooth brushing and preventing dental problems

Matthew Sawyer
Matthew Sawyer • 7 May 2024
7 comments

How effective is tooth brushing to prevent dental problems? (I'd appreciate help finding the answer rather than I know the answer already!)

Tooth brushing is good for oral health - the WHO says so - https://www.who.int/news-room/fact-sheets/detail/oral-health. But there seems relatively few research articles on how much tooth brushing is needed to prevent a dentist-treatable oral health problem (ie cavity). What is the NNT? How many people would need a powered toothbrush to demonstrate benefit over using a manual one?

In 2016, the NYTimes published an article (https://www.nytimes.com/2016/08/30/upshot/surprisingly-little-evidence-…) showing there is pretty weak (randomised controlled) evidence for most current 'wisdom' (e.g. for flossing, annual xrays, scale and polishes) other than for fluoride toothpaste (and probably powered toothbrushes).

Links to Evidence Based Dentistry (https://www.nature.com/ebd/research-articles) have gaps from 1 article in 2019, and nil until 2023 - but finding one on the NNT with tooth brushing isnt easy...

Any dental experts able to shine a light?

Comments (7)

Paul Ashley
Paul Ashley • 7 months ago

Lyne, A., Ashley, P., Saget, S. et al. Combining evidence-based healthcare with environmental sustainability: using the toothbrush as a model. Br Dent J 229, 303–309 (2020). https://doi.org/10.1038/s41415-020-1981-0

Ashley, P., Duane, B., Johnstone, M. et al. The environmental impact of community caries prevention - part 2: toothbrushing programmes. Br Dent J 233, 295–302 (2022). https://doi.org/10.1038/s41415-022-4905-3

You might find what you need in the above

Matthew Sawyer
Matthew Sawyer • 7 months ago

Fab thanks. Id seen the first paper, but the second is probably what Im after to add some extra info.
However, the answer to how many 'tooth brushings are needed to prevent one caries' or 'how many children need to be taught effective tooth brushing to prevent one caries' still eludes me...
Ive read this (https://pubmed.ncbi.nlm.nih.gov/35138648/) which is 'number of dental visits needed to prevent a caries' (NNT = 2.2 children to prevent one caries (in Malaysia rather than UK)). If this was true for the UK too, then lends huge weight to the sustainability/prevention approach

Matthew Sawyer
Matthew Sawyer • 7 months ago

Thank you. Impressive figures from Scotland! A fall from 60% of 5yr old children having caries in 2000 to 26% in 2020. Looks like >3yrs of supervised brushing and dental visits had the largest impact (fluoride varnish had NNT 21). The cohort was 50,000 - so children with caires would fall from 30,000 to 13,000 (rather than number of caries in total - as the worst children would have multiple). Makes me wonder why this isnt on the English NHS agenda akin to the services offered with SureStart centres from 20 years ago...

Paul Ashley
Paul Ashley • 7 months ago

And remember for caries prevention it's tooth brushing with a fluoride toothpaste. Tooth brushing on its own probably isn't that helpful. And then you need to be mindful of the fluoride toothpaste concentration

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