Dental x-rays linked to common brain tumor

 

   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."

 

5  Major Health Threats That Your Dentist Can Predict

 

When you look in your mouth you may see teeth that need whitening, but a dentist may see signs of heart disease. A study published in the Journal of Dental Research found that many dental problems can be signs of serious health complications. University of Washington School of Dentistry professor Philippe P. Hujoel, DDS, PhD, says the sugar and carbohydrates in food, known as "fermentable carbohydrates," are to blame. Found in sugary drinks, snack foods like potato chips, and simple grains like white bread and corn, these carbs are fermented by bacteria in your mouth, which produces the acids that cause tooth decay. "Those dental diseases are a marker for an unhealthy diet, and an unhealthy diet may predict future health complications," Dr. Hujoel notes.

#1: Obesity

"If a kid has tooth decay and cavities, he probably has high exposure to fermentable carbs," Dr. Hujoel says. "He's really having too many snacks and candy, and this may very well be the kid that ends up obese." For adults, too, an increase in cavities could mean you're eating too many unhealthy foods, which also puts you at risk for obesity. A dentist who knows your medical history may ask about your eating habits, but you should feel free to ask if what's happening to your teeth might be a sign of other problems.

#2: Cardiovascular disease

The same carbs in snack foods and sugary drinks that get dentists drilling are often found in the company of unhealthy ingredients like trans fatty acids. While trans fats themselves don't cause cavities, they're often used in foods with high amounts of cavity-causing fermentable carbs, and they have been associated with an increase in cardiovascular disease. Whenever you can, replace processed, packaged food with fruits, vegetables, and whole grains. For those sweet treats you can't give up, check the labels to make sure they're trans fat free.

It's also possible for cavities themselves to threaten your heart, if the bacteria that produce them find their way into your cardiovascular system. Bacteria associated with tooth and gum disease may also be involved in stroke, diabetes, and respiratory problems—so brush and floss every day.

#3: Diabetes

The fermentable carbohydrates in sugary drinks and snacks loaded with carbs increase your blood sugar level drastically, raising the risk of type 2 diabetes, Dr. Hujoel says. Which is one more reason to switch to a diet that produces fewer cavities. "Lifelong usage of high fermentable carbohydrates first leads to dental disease, and then, long-term, leads to other health outcomes," Dr. Hujoel adds.

#4: Cancer

Not only does a tooth-unhealthy diet put you at risk for obesity, which is a risk factor for certain cancers, harmful lifestyle habits like smoking can produce tooth discoloration and periodontal destruction. Abnormalities in your mouth, including bleeding gums and cavities, should be a natural alarm bell, Dr. Hujoel says. So always ask your dentist if your tooth problems could point toward a wider problem.

 

#5: Alzheimer's disease

In a study just published in The Journal of the American Dental Association, people who lost most of their teeth were more likely to develop dementia problems, such as Alzheimer's disease, later on. It will take more research to clarify what the connection between tooth loss and brain health may be. But is seems that keeping your teeth as healthy possible has benefits that go far beyond your mouth.