"Long before it's in the papers"
April 11, 2012

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Tumor risk from dental X-rays not eliminated, study finds

April 11, 2012
Courtesy of Wiley-Blackwell
and World Science staff

A high­er risk of brain tu­mors as­so­ci­at­ed with den­tal X-rays per­sists, de­spite the fact that low­er X-ray doses are used than in dec­ades past, a study has found.

On the pos­i­tive side, the type of brain tu­mor linked to den­tal X-rays in the study is a rare one and usu­ally non-cancerous, or be­nign.

The re­search, pub­lished in the ad­vance on­line edi­tion of the jour­nal Can­cer, found that pa­tients who re­ceived fre­quent den­tal x-rays in the past have a high­er risk of de­vel­op­ing menin­giomas, the most com­monly di­ag­nosed pri­ma­ry brain tu­mor in the Un­ited States.

A menin­gioma is a tu­mor aris­ing from the me­nin­ges, mem­branes that sur­round the brain and spi­nal cord. About one in 50,000 Amer­i­cans are di­ag­nosed with the con­di­tion at some point.

Eliz­a­beth Claus of the Yale Uni­vers­ity School of Med­i­cine in New Hav­en and Brig­ham and Wom­en’s Hos­pi­tal in Bos­ton and col­leagues stud­ied in­forma­t­ion from 1,433 pa­tients di­ag­nosed with menin­giomas be­tween ages 20 and 79. They were di­ag­nosed in Con­nect­i­cut, Mas­sa­chu­setts, North Car­o­li­na, the San Fran­cis­co Bay Ar­ea, and eight coun­ties in Hous­ton, Tex­as, be­tween May 1, 2006 and April 28, 2011. 

The in­ves­ti­ga­tors al­so stud­ied in­forma­t­ion from 1,350 peo­ple who had si­m­i­lar char­ac­ter­is­tics but had­n’t been di­ag­nosed with a menin­gioma.

Over a life­time, pa­tients with menin­gioma were more than twice as likely to re­port hav­ing ev­er had a bite­wing ex­am, which uses an x-ray film held in place by a tab be­tween the teeth, Claus and col­leagues found. Peo­ple who re­ported re­ceiv­ing bite­wing ex­ams on a yearly or more fre­quent ba­sis were 1.4 to 1.9 times as likely to de­vel­op menin­gioma as oth­er peo­ple, the sci­ent­ists said. The risks were found to dif­fer de­pend­ing on the age at which the ex­ams were done.

An in­creased risk of menin­gioma was al­so linked with panorex ex­ams, which are tak­en out­side of the mouth and show all of the teeth on one film, tak­en at a young age or on a yearly or more fre­quent ba­sis. Peo­ple who re­ported re­ceiv­ing these ex­ams when they were young­er than 10 years old had a 4.9 times in­creased risk of de­vel­op­ing menin­gioma. Those who re­ported re­ceiv­ing them on a yearly or more fre­quent ba­sis were 2.7 to 3.0 times (de­pend­ing on age) as likely to de­vel­op menin­gioma as oth­er peo­ple.

The re­search­ers not­ed that to­day’s den­tal pa­tients are ex­posed to low­er doses of radia­t­ion than in the past. None­the­less, “the study pre­s­ents an ide­al op­por­tun­ity in pub­lic health to in­crease aware­ness re­gard­ing the op­ti­mal use of den­tal x-rays, which un­like many risk fac­tors is mod­i­fi­able,” said Claus. 

“The Amer­i­can Den­tal As­socia­t­ion’s guide­lines for heathy per­sons sug­gest that chil­dren re­ceive one X-ray ev­ery 1-2 years, teens re­ceive one X-ray ev­ery 1.5-3 years, and adults re­ceive one X-ray ev­ery 2-3 years,” she added. A 2006 state­ment by the Amer­i­can Den­tal As­socia­t­ion high­lights the need for den­tists to ex­amine the risks and ben­e­fits of X-rays and says there’s lit­tle ev­i­dence to sup­port their use on all teeth in symptom-free pa­tients.

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A higher risk of brain tumors associated with dental X-rays persists, despite the fact that lower X-ray doses are used than in decades past, a study has found. On the positive side, the type of brain tumor linked to dental X-rays in the study is a rare one and usually non-cancerous, or benign. The research, published in the advance online edition of the research journal Cancer, found that patients who received frequent dental x-rays in the past have a higher risk of developing meningiomas, the most commonly diagnosed primary brain tumor in the United States. A meningioma is a tumor arising from the meninges, membranes that surround the brain and spinal cord. About one in 50,000 Americans are diagnosed with the condition at some point. Elizabeth Claus of the Yale University School of Medicine in New Haven and Brigham and Women’s Hospital in Boston and colleagues studied information from 1,433 patients diagnosed with meningiomas between ages 20 and 79. The patients were diagnosed in Connecticut, Massachusetts, North Carolina, the San Francisco Bay Area, and eight counties in Houston, Texas, between May 1, 2006 and April 28, 2011. The investigators also studied information from 1,350 people who had similar characteristics but hadn’t been diagnosed with a meningioma. Over a lifetime, patients with meningioma were more than twice as likely to report having ever had a bitewing exam, which uses an x-ray film held in place by a tab between the teeth, Claus and colleagues found. Peple who reported receiving bitewing exams on a yearly or more frequent basis were 1.4 to 1.9 times as likely to develop meningioma as other people. The risks were found to differ depending on the age at which the exams were done. An increased risk of meningioma was also linked with panorex exams, which are taken outside of the mouth and show all of the teeth on one film, taken at a young age or on a yearly or more frequent basis. Individuals who reported receiving these exams when they were younger than 10 years old had a 4.9 times increased risk of developing meningioma. Those who reported receiving them on a yearly or more frequent basis were 2.7 to 3.0 times (depending on age) as likely to develop meningioma as other people. The researchers noted that today’s dental patients are exposed to lower doses of radiation than in the past. Nonetheless, “the study presents an ideal opportunity in public health to increase awareness regarding the optimal use of dental x-rays, which unlike many risk factors is modifiable,” said Claus. “The American Dental Association’s guidelines for heathy persons suggest that children receive 1 x-ray every 1-2 years, teens receive 1 x-ray every 1.5-3 years, and adults receive 1 x-ray every 2-3 years. Widespread dissemination of this information allows for increased dialogue between patients and their health care providers,” she added. A 2006 statement by the American Dental Association highlights the need for dentists to examine the risks and benefits of dental x-rays and said there’s little evidence to support the use of x-rays of all teeth in symptom-free patients.