People who underwent frequent dental X-rays in the past, before radiation doses were lowered, may be at greater risk for a usually benign form of tumor in the lining of the brain, called meningiomas, a recent study suggests.

Meningiomas affect the lining of the brain and the spinal cord. More than 90% are classified as benign, not malignant. But in some cases they can grow to the size of a baseball and disrupt the brain's functioning, leading to vision problems, headaches, hearing and memory loss, and seizures. Neurosurgeons often try to remove them in the most severe cases.

"They cause problems as soon as they achieve a certain size, because there is no room in the skull to accommodate growth. Any growth that is more than a couple centimeters can result in symptoms," explained Isabelle Germano, MD, director of the Comprehensive Brain Tumor Program at Mount Sinai School of Medicine in New York City.

The recent research doesn't definitively link dental X-rays to the tumors, which affect about 1% of people. It's also possible that dental X-rays, which are now given at a lower radiation dose, have nothing to do with the tumors.

Still, the study suggests that dental X-rays could be a risk factor for the tumors, said study author Elizabeth Claus, MD, PhD, a neurosurgeon at Brigham & Women's Hospital in Boston and a professor of epidemiology at Yale University School of Medicine.

Study Details

In the study, researchers sought to determine whether dental X-rays are connected to meningiomas that affect the lining of the brain specifically.

The researchers examined a group of more than 1,400 patients ages 20 to 79 who were treated for the tumors between 2006 and 2011, and compared them with 1,350 similar people who did not develop the tumors. The average age in both groups was about 57.

Those with tumors were more than twice as likely as the others to report having more frequent bitewing X-rays (at any time) and panorex X-rays (especially at a young age).

Bitewing X-rays allow views of the back teeth—patients bite onto a tab during the X-rays. Panorex X-rays show the whole area in and around the mouth from below the nose to the chin.

The design of the study didn't allow the researchers to specify the level of increased risk of a tumor that a person who's had dental X-rays would conceivably face. It does appear, however, that the raised risk would remain low, Dr. Claus said.

Overall, more than 92% of people in the study reported having had at least one bitewing X-ray.

The findings suggest that patients should talk to their dentists about the possible dangers of X-rays and be aware of national recommendations regarding their use, Dr. Claus pointed out.

"I do not get the feeling that people are aware of those guidelines," she said. "Many people are having them every six months or every year when the American Dental Association is saying once every two to three years." (That's the recommendation for the patient who's never had a cavity or only a small number of fillings and isn't at increased risk for a cavity.)

The study appeared in the journal Cancer.

Expert Comment

Matthew Messina, DDS, a Cleveland dentist and spokesman for the American Dental Association, said one weakness of the study is that people's memories about their X-rays are fuzzy.

"It's difficult to pin this down," he said, especially without dental records.

Dr. Messina added that the amount of radiation in dental X-rays has gone down significantly over the years, thanks to factors such as the improved speed of X-ray film and the advent of digital X-rays.

The study was also observational in nature, meaning it can show an association but not cause-and-effect.

So what should patients do?

Dr. Germano concurred with Dr. Claus that adult patients and parents of child patients should talk to their dentists about X-rays.

"It's always important to discuss what the Xray is for and what the advantage is. It's not a good idea to assume that X-rays are a benign procedure," she said.

Dr. Messina also agreed. "It's always good for patients to talk to their dentists about why they're getting X-rays and what is being done to shield the patient."

Overall, dentists are trying to balance the possible dangers of radiation and the usefulness of X-rays, Dr. Messina said. "We take dental X-rays because we're trying to make sure the person is healthy or trying to diagnose what's wrong with them."

Dangerous Tooth Pain Gels And Sprays

These products containing benzocaine are sold over the counter to relieve pain from teething or canker sores, for example. They can lead to methemo-globinemia—a potentially fatal condition in which the amount of oxygen in the bloodstream is reduced—even after a single use. Symptoms, which include pale, gray or blue-colored skin, lips and nail beds...headache...light-headedness...rapid heart rate...fatigue and shortness of breath, usually appear within hours of application. If affected, seek medical attention immediately.

Concerned About Mercury in Your Mouth? Ask for This Instead…

Ask your dentist about porcelain if you need A to have a tooth filled but are concerned about amalgam.

Recent development: An FDA advisory committee has recommended that the agency review its 2009 ruling stating that the mercury from amalgam fillings poses no safety risk. The American Dental Association maintains that amalgam fillings are safe, but new data has raised additional concerns that mercury vapors from these fillings may harm the body-especially the brain and kidneys.

If you prefer not to receive an amalgam filling: Discuss options with your dentist. Porcelain is superior to resin because it does not degrade over time the way resin can.

Illegal Chelation Products

Over-the-counter chelation products sold online are illegal. Genuine chelation—available only with a prescription—is used to treat people who have been poisoned with heavy metals, such as lead and mercury. Sellers of online products falsely claim that their products can be used to treat autism, heart disease and other chronic diseases.

Warning: Chelation can cause dehydration, kidney failure and even death and should always be supervised by a health-care professional.

Cancer-Causing Home-Building Material

A common home-building material may A cause cancer. Formaldehyde typically is found in plywood, particleboard and other wood composites, such as medium-density fiberboard (MDF) used to make furnishings and in housing construction. It has been officially identified by the National Institutes of Health as a possible cause of cancer.

Self-defense: Buy formaldehyde-free products, such as ones made of solid wood, or products labeled ULEF (ultra-low-emitting formaldehyde). The half-life of formaldehyde emissions is about one year, so if products have been in your home for many years, current offgassing may be negligible.

Avoid Using Airplane Restrooms

Restrooms on airplanes are rarely sanitized during flights and often are infected with E. coli and other harmful bacteria. If you have to use the bathroom, use a paper towel to open and close the toilet lid...turn faucets off and on...and open the door. When you get back to your seat, use sanitizer to disinfect your hands.

Items to Clean in Your Hotel Room

Clean your hotel room's TV remote, alarm clock and ice bucket before using them. These items are rarely cleaned by housekeepers.

Also likely to be covered in germs: The steering wheel and gearshift of a rental car.

When "Green" Doesn't Mean Good

Avoid scented cleaning and laundry products. Even products that claim to be “green," "organic" or "natural" may emit hazardous chemicals.

Recent finding: Nearly one-quarter of chemicals emitted by scented household products, such as air fresheners, detergents, fabric softeners and disinfectants, are classified as toxic or hazardous...and more than one-third of products tested emitted at least one chemical identified as a probable carcinogen.

To avoid potentially dangerous chemicals: Clean with baking soda and/or windows for ventilation instead of using air fresheners...and buy products without any fragrance.

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