Q: Are dental X-rays harmful to my body?

A: Dentists rely on X-rays to reveal cavities between teeth, infections in the bone, abscesses, cysts, abnormalities, impacted wisdom teeth, and even some types of tumors. Certainly, radiation in large doses is harmful, but the amount you receive in the dentist chair is small.

"You get more radiation from 30 minutes of watching a color TV than from four bitewing X-rays," says Dr. Isbell, a dentist in Gadsden, Alabama. Bitewing X-rays are the ones that show crowns of several upper and lower teeth at once.

Dentists often refrain from ordering X-rays if they can refer to current pictures from other dentists. They usually take bitewing X-rays every six months or once a year. Whole mouth X-rays are generally taken once every four years.

Most dentists minimize radiation by using lead aprons, focusing the beam on only the area needing to be examined, and using the fastest X-ray film available. A new dental imaging system uses an X-ray-sensitive computer chip to take pictures, emitting only 10 percent of the usual radiation dosage.