A study from the University of York looking into how financial arrangements with dentists affect what goes on in the dentist's chair has found a marked increase in the number of X-rays when dentists receive payment for them. It concludes that dentists' calculation of the benefits vs the risks of X-rays is being distorted by financial incentives.
The research, reported in the Journal of Health Economics, examined extensive data from dentists and patients over a 10-year period and found a significant increase in the number of X-rays given to patients when dentists were paid on a 'fee-for-service' basis, where each item of treatment delivered is charged for, compared to when they are on a fixed salary. The researchers detected the biggest increase in the rates of X-rays when patients were also exempt from charges. The authors of the report are calling for a review into how dentists are paid and whether current guidelines go far enough to protect the public.
Co-lead author of the study Professor Martin Chalkley from the Centre for Health Economics at the University of York said: "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."
The study examined a uniquely detailed data set gathered between 1998 and 2007 by NHS Scotland on Scottish dentists and their patients. Scotland employs a mixture of 'fee-for-service' and salaried dentists. This means that some dentists are able to charge separately for each service they provide- a cost that is then normally shared between the patient and the NHS -- while other dentists receive a fixed wage regardless of the treatments they provide. The presence of the two payment methods in Scotland allowed the researchers to compare their effect on dentist's behaviour. Fee-for-service is a prevalent billing system in dentistry worldwide; Scottish data was used for the study because it is uniquely detailed.
Co-lead author of the study Professor Stefan Listl said: "While dental X-rays are an important diagnostic tool and are important for some procedures such as root-canal treatment, current regulations and guidelines state that any unnecessary x-ray exposure should be avoided. We can't say whether our study observed excessive X-raying, but we can say that the amount of X-raying differed according to the financial arrangement. "
Journal Reference: Martin Chalkley, Stefan Listl. First do no harm – The impact of financial incentives on dental x-rays. Journal of Health Economics, 2017; DOI: 10.1016/j.jhealeco.2017.12.005