For too many dentists, the X-ray machine is more like a cash machine.

They don't use it when they absolutely need images to diagnose a problem in your mouth. They use it the moment your insurance company will allow them to make a new set of images.

It's pretty easy money: Push button, cash check.

Meanwhile, you get exposed to radiation and all the risks that come with it -- including brain tumors, as a new study finds that dental images can double your risk or more.

Researchers from Yale, Harvard, and several other institutions interviewed 1,433 people with a type of tumor called a meningioma as well as 1,350 people without the condition matched for age, gender, income, race, and more.

They found that people who had annual "bitewing X-rays" had double the tumor risk, while regular "panorex dental exams" starting before the age of 10 caused that risk to shoot up by 500 percent.

The panorex exam is when a single image of all teeth is taken from outside the mouth, and even starting after the age of 10 boosted the risk. In fact, patients of any age who received annual panorex exams had triple the risk of meningioma.

But is this really a surprise? A dental X-ray is basically a blast of radiation aimed right at your noggin -- and while meningioma is still pretty rare and often non-fatal, you certainly don't want to boost your odds of getting one.

Besides, the risks don't end there -- because dental X-rays can also increase your chance of getting thyroid cancer. A 2010 study, for example, found that people who have 10 or more dental X-rays over the course of a lifetime have 5.4 times the risk of thyroid cancer of people who've never been X-rayed.

Throw in the fact that many dentists still work with fluoride and mercury along with all that radiation, and your annual exam could quickly become one of the riskiest things you'll ever do in the name of "health."

I won't say don't ever visit the dentist. Clean teeth and gums are important to your overall health, and people with bad oral hygiene and gum disease have a higher risk of heart problems.

But when you do visit the dentist, set some ground rules: No fluoride... no mercury... and no X-rays unless they're absolutely necessary and your dentist has a good reason.

Your best approach is to see a holistic dentist, sometimes referred to as a biological dentist, who is sensitive to these issues.

I'm not done with dental health yet -- and if you or anyone you love wears dentures, keep reading for a warning you don't want to miss.