Are dentists getting greedy over X-rays?

X-rays should be performed only when clinically appropriate, but a new study finds that dentists often take money into consideration.

Dental X-rays are the most common form of X-ray radiation most people receive. Though they are relatively common, they are a known carcinogen. To minimize exposure, X-rays are only to be given when clinically necessary. But what happens in a fee-for-service model, where more X-rays can turn into more profits?

Researchers in the United Kingdom asked this question, and came to the conclusion that the promise of more money is a factor in the number of X-rays performed. Their study, published in the Journal of Health Economics, shows that “there are significant increases in X-rays when dentists receive fee-for-service rather than salary payments and when patients are made exempt from payment.”

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To find their answer, researchers examined data from the NHS in Scotland. In Scotland, dentists working in the public sector are either reimbursed in a fee-for-service model or are salaried, with income independent of services performed. Patients receiving care from public dentists are either exempt from charges or if non-exempt pay 80 percent of the treatment fee up to a certain amount.

Using claim data from 1998 to 2007 - about 1.2 million total claims covering over 200,000 patients and 3,144 dentists - the researchers discovered differences between the number of x-rays given by salaried dentists and fee-for-service dentists.

During that long period, some of those dentists switched between salaried and fee-for-service payment models, giving an even clearer picture of the number of X-rays given under each model. Dentists who switched from salary to fee-for-service were 6.3 percent more likely to give an X-ray after the change. For patients making the change from non-exempt to exempt, the likelihood of receiving an X-ray increased by 3.4 percent.

Overall, exempt patients receiving treatment from a fee-for-service dentist were 4.1 percent more likely to receive an X-ray than a non-exempt patient receiving treatment from a salaried dentist.

Also of interest, older dentists were more likely to give x-rays, while older patients were less likely to receive an X-ray.

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Co-author Martin Chalkley of the Centre for Health Economics at the University of York says that “Our study clearly shows that a potentially harmful treatment is being given in varying quantities according to how dentists are paid for it and we believe this is a genuine cause for concern. Dental X-rays deliver a very small dose of radiation, but there are no safe levels - every last bit of radiation is potentially harmful. Each dentist has to weigh up the risks versus the benefits before they take the decision to X-ray and our findings indicate that this calculation is being distorted by financial incentives.”


“First do no harm – The impact of financial incentives on dental X-rays.” Published in the Journal of Health Economics DOI: 10.1016/j.jhealeco.2017.12.005