If you’ve been to the dentist, you know how it is — these jokers want to X-ray you every time you open your mouth.

Checkup? ZAP! Toothache? ZAP! New dentist? ZAP! They’ll even try to zap you if they get new office equipment.

Zap, zap, zap, zap — each time your dentist hits that switch, you get hit with a powerful blast of radiation right in your face. Don’t think for a second that it’s safe — because a new study shows how all those dental X-rays can turn into a battle for your life with thyroid cancer.

British researchers looking into the alarming rise of this unusual cancer found that patients who’ve been X-rayed 10 times or more have 5.4 times the thyroid risk when compared to those smart enough to avoid dental X-rays, according to the study in the journal Acta Oncologica.

The study, which used data from 313 thyroid cancer patients and a similar number of people who didn’t have the condition, also found that between five and nine X-rays will quadruple your risk, and getting zapped up to four times will double your risk.

The researchers say dentists should lay off the radiation trigger, and stop giving X-rays for routine exams or when accepting new patients.

It’s so bad that many people get hit with more radiation during dental visits than during all their other health appointments put together, and the new study shows how that little lead bib isn’t going to save you.

And when your dentist isn’t zapping you, he’s often packing your teeth with some of the most powerful poisons on earth: sodium fluoride and mercury.

Yet another new study shows how dental health stretches from your mouth right down into your chest, because people who have the cleanest teeth have the lowest heart risk.

A survey of some 12,000 people in Scotland found that those who rarely or never brushed their teeth had more than just bad breath — they also had a 70 percent higher risk of heart attack, stroke or other cardiovascular problems.

These ogre mouths also had higher levels of C-reactive protein, an inflammation marker, and a much more reliable indicator of heart risk than cholesterol.

But since we’re talking teeth, let me answer a question I get all the time: “Doc, how can I keep my mouth clean when you keep telling me to avoid the dentist?”

Easy — just forget everything you’ve been told about dental care. Take anything in your house with sodium fluoride in it — toothpaste, mouthwash, all of it — and toss it. Don’t save it, don’t set it aside and don’t put it in the guest bathroom.

All you need is a little baking soda and some plain old 3 percent hydrogen peroxide. Combine a little of each to make a paste, then gently rub it into your teeth and gums after meals. Don’t even bother with a toothbrush. Then, rinse with some of that peroxide (just don’t swallow it).

Avoid anything with sugar, and you may never need to see a dentist again.