By Andrew M. Seaman
NEW YORK | Wed Apr 11, 2012 5:37pm EDT
(Reuters Health) ? A new study suggests people who had certain kinds of dental X-rays in the past may be at an increased risk for meningioma, the most commonly diagnosed brain tumor in the U.S.
The findings cannot prove that radiation from the imaging caused the tumors, and the results are based on people who were likely exposed to higher levels of radiation during dental X-rays than most are today.
?It?s likely that the exposure association we?re seeing here is past exposure, and past exposure levels were much higher,? said Dr. Elizabeth Claus, the study?s lead author and a professor at the Yale School of Medicine in New Haven, Connecticut.
Claus and her colleagues write in the journal Cancer that dental X-rays are the most common source of exposure to ionizing radiation ? which has been linked to meningiomas in the past ? but most research on the connection is based on people who were exposed to atomic bombs or received radiation therapy.
There have been some studies that looked at dental X-rays, but they were from years ago and included fewer people than the current study, Claus noted. Still, they were generally in agreement with the new findings.
For her study, Claus? team recruited 1,433 people diagnosed with intracranial meningioma ? a tumor that forms in the tissues lining the brain ? between May 2006 and April 2011. All of the participants were diagnosed when they were between 20 and 79 years old and they were all from Connecticut, Massachusetts, North Carolina or the Houston or San Francisco Bay areas.
For comparison, the researchers also followed 1,350 people who were similar in age, sex and state of residence as the study group, but who had not been diagnosed with a tumor.
The study looked at how often people had three different types of dental X-rays. They included a focused image of one area, a number of images of the full mouth and a single panoramic view of the entire mouth. These are known in dentistry parlance as bitewing, full-mouth and panorex films, respectively.
Each person was interviewed by someone trained to administer a questionnaire that asked about demographic details, family history of cancer, pregnancy and medical history. The interviewers also asked ? among other things ? about the person?s history of dental work and the number of times they had the three types of dental x-rays taken throughout their life.
The researchers found that those diagnosed with meningiomas were more than twice as likely as the comparison group to report ever having had bitewing images taken.
And regardless of the age when the bitewings were taken, those who had them yearly or more frequently were at between 40 percent and 90 percent higher risk at all ages to be diagnosed with a brain tumor.
To put that in perspective, Dr. Paul Pharoah, a cancer researcher at the University of Cambridge said in a statement the results would mean an increase in lifetime risk of intracranial meningioma in the U.K. from 15 out of every 10,000 people to 22 in 10,000 people.
Panoramic X-rays taken at a young age, especially if done yearly or more often before age 10, also raised the risk of meningiomas by up to five times.
There was no association between full-mouth X-rays and the tumors, although the authors note they saw a trend similar to that seen for the bitewing X-rays.
The lack of association with full-mouth X-rays led one expert to question the connection.
?They found a small risk (from) a pair of bitewings, but not a full mouth series, which is multiple bitewings. That inconsistency is impossible to understand to me,? said Dr. Alan Lurie, president of the American Academy of Oral and Maxillofacial Radiology.
Lurie also echoed Claus? caution that radiation levels from dental X-rays when some of the participants were younger was much greater than is used now.
He does warn, however, patients shouldn?t assume it?s fine for the dentist to take X-rays.
?They should ask why are (dentists) taking this image and what is the benefit to me,? he said.
The American Dental Association put out a statement in response to the study noting that the interviews relied on participants? memories of how often they had different types of X-rays years earlier.
The statement added, ?The ADA?s long-standing position is that dentists should order dental X-rays for patients only when necessary for diagnosis and treatment. Since 1989, the ADA has published recommendations to help dentists ensure that radiation exposure is as low as reasonably achievable.?
Dr. Sanjay Mallya, an assistant professor the UCLA School of Dentistry in Los Angeles, said that patients should be concerned whenever they are exposed to radiation, but ?it?s important to emphasize that this concern should not mean that we shouldn?t get X-rays at all.?
According to the researchers, ?while dental X-rays are an important tool in well selected patients, efforts to moderate exposure to (ionizing radiation) to the head is likely to be of benefit to patients and health care providers alike.?
SOURCE: bit.ly/HwspDv Cancer, online April
Source: http://www.reuters.com/article/2012/04/11/us-dental-x-rays-idUSBRE83A1E820120411
Academy of General Dentistry Responds:
CHICAGO, April 12, 2012 /PRNewswire via COMTEX/ ? On Tuesday, April 10, 2012, in the journal Cancer, the American Cancer Society published an article entitled ?Dental X-Rays and Risk of Meningioma,? which summarized a study that sought to develop a correlation between dental radiographs and brain cancer.
According to the Academy of General Dentistry (AGD), a professional association of more than 37,000 general dentists dedicated to providing quality dental care and oral health information to the public, the study?s findings are not applicable to modern dentistry because the study was based upon an examination of outdated radiographic techniques, which produced considerably more radiation than patients would be exposed to today.
?Modern radiographic techniques and equipment provide the narrowest beam and shortest exposure, thereby limiting the area and time of exposure and reducing any possible risks while providing the highest level of diagnostic benefits,? said AGD President Howard Gamble, DMD, FAGD. ?Today, patient safety is always maintained with the recommended use of thyroid collars and aprons.?
The article from the American Cancer Society, which received attention from many reputable news outlets, could cause the public to decide to limit or even refuse X-rays in an effort to keep their families safe.
?It is regrettable to think that an article based on outdated technology could scare the public and cause them to avoid needed treatment,? said Dr. Gamble. ?With the radiography techniques in use today, the amount of radiation exposure is reduced and more controlled than it was in years past.?
The AGD supports radiographic guidelines provided by the American Dental Association (ADA) and the U.S. Food & Drug Administration, and concurs with the ADA that dentists should order dental radiographs for patients only when necessary for diagnosis and treatment.
The AGD encourages patients to discuss their concerns with their dentists in order to determine what?s best for them. The AGD also encourages dentists to communicate with their patients and address any unexpressed concerns of radiographic risks in order to reduce fear and promote a better understanding of the benefits and the risks associated with the specific needs of each patient.
?Neglecting one?s oral health has serious oral and systemic risks,? said Dr. Gamble. ?Radiographs play an important role in improving the oral health of the public, and patients should not be deterred from seeking oral health care due to misperceptions from this study.?
The Cancer study contained many inconsistencies and possibilities for error, including the fact that its findings were based upon a population-based case-control study. This means that it relied upon the patients themselves to recall and self-report past events, many of which were from decades earlier.
The AGD supports ongoing scientific research on any correlations between dental radiographs and incidents of disease in an effort to provide the most accurate information to the public and to correct any misperceptions created by the Cancer study.
About the Academy of General DentistryThe Academy of General Dentistry (AGD) is a professional association of more than 37,000 general dentists dedicated to providing quality dental care and oral health education to the public. AGD members stay up-to-date in their profession through a commitment to continuing education. Founded in 1952, the AGD is the second largest dental association in the United States, and it is the only association that exclusively represents the needs and interests of general dentists. A general dentist is the primary care provider for patients of all ages and is responsible for the diagnosis, treatment, management, and overall coordination of services related to patients? oral health needs. For more information about the AGD, visit www.agd.org .
SOURCE Academy of General Dentistry
Copyright (C) 2012 PR Newswire. All rights reserved
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