COMMENTARY

What Are the Risks of Dental X-rays?

Sotirios Tetradis, DDS, PhD; Stuart C. White, DDS, PhD

Disclosures

August 10, 2012

In This Article

Dental Radiographs and Risk for Meningioma

A recent article by Claus and colleagues[1] reporting an association between dental radiographs and meningiomas has led to renewed concern about the safety of dental x-rays. We will first consider this reported association between dental radiograph and meningiomas, then explore the risks from dental imaging, and finally discuss appropriate use of dental radiographs.

These researchers identified 2228 eligible patients with intracranial meningioma and recruited 2604 matched controls. Participation was 65% for meningioma patients and 52% for controls. Subjects were asked to report their history of bitewing, full-mouth, or panoramic radiographic examinations. The association of meningioma odds with the odds of dental radiographs was calculated by conditional logistic regression for maximum-likelihood estimation of odds ratio, adjusted for age, sex, race, education, and history of head CT.

The researchers reported an association between intracranial meningioma and bitewing radiographs obtained at 10-19 and 20-49 years of age, as well as for all ages combined. Additionally, an association between meningioma and panoramic radiographs at younger than 10 and 10-19 years of age is identified. Finally, an association between meningioma and frequency of panoramic radiographs across all groups, for those with yearly or more frequent radiographs is described. Of note, there was no significant association between intracranial meningioma and full-mouth series. The manuscript concludes that "exposure to some dental x-rays performed in the past, when radiation exposure was greater than in the current era, appears to be associated with an increased risk of intracranial meningioma."

This manuscript, studying the largest cohort of subjects to date, is a significant contribution to existing literature reporting a potential association of intracranial meningioma and dental radiographs.[2,3,4,5,6,7] However, methodologic details are difficult to evaluate, thus creating ambiguities when performing detailed analysis of the data. For example, although controls were matched for state of residence, local differences do not appear to have been considered. Thus, controls with significantly different dental awareness or access to dental care could have been recruited. No distinction is made between bitewing and selected periapical radiographs. No adjustment for income between patients and controls was performed. The ability of patients and controls to accurately recall history of dental radiographs in a way that would not influence the study findings was not assessed. Finally, the prevalence of dental disease that might affect need for dental radiographs was not evaluated.

Notwithstanding such shortcomings, we believe that a weak association between intracranial meningiomas and dental radiographs may exist.[8] However, current understanding of radiation biology and radiation-induced tumorigenesis (see Radiation Risk From Dental Radiography section below) suggests that an additional 0.02-0.07 mGy to the brain from dental bitewing and panoramic radiography is highly unlikely to contribute measurable risk. Other explanations for such a risk should be considered. An obvious possibility is that patients with intracranial meningiomas have increased odds to receive bitewing or panoramic radiographic examinations.

Meningiomas can cause referred pain and discomfort from various structures of the orofacial complex, including the teeth, temporomandibular joint, and face, prior to their diagnosis.[9,10,11,12,13,14,15,16,17,18] Such referred pain could lead the patient to the dentist, who would use bitewing, periapical, or panoramic radiographs in an effort to identify an oral etiology for the patient's symptoms. Using the reported, nonadjusted numbers of patients by Claus and colleagues, we estimate that it would take only 40 such patients (<3% of cases) for bitewing or 24 patients (<2% of cases) for panoramic radiographs to account for most of the reported associations.

Yet another possibility that could account for the reported association is that a third variable relates intracranial meningiomas and dental radiographs. Head trauma, particularly in young age, could be such a variable. Head trauma has been associated with risk for intracranial meningioma.[19,20,21] Furthermore, if head trauma were associated with trauma to the face, dental radiographs might be required to evaluate the integrity of the orodental structures.

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