Q: Are dental X-rays harmful, and are they necessary?
— Jessie J. Reno, Nev.
A: Depending on your age (kids may need them more often) and whether you have a lot of decay or bone loss (that affects older folks), your dentist will suggest when and how often you need X-rays.
A full set of dental X-rays is appropriate if you haven't been to the dentist in more than a year. They let your dentist see things that aren't apparent when doing a standard exam and cleaning, such as the extent of gum disease, bone decay, decay under fillings or caps and even tumors. The risks from dental X-rays have decreased, and they now deliver the lowest dose of radiation of any medical X-ray. Two to four images of your back teeth expose you to about 0.005 millisieverts of radiation.
Nonetheless, if you're going to be zapped, you should be given a lead bib and a thyroid shield/collar to wear. Generally, pregnant women should skip any X-rays if possible.
By comparison, the average North American is exposed to 3.1 millisieverts from the environment annually. Various estimates conclude that 50 percent to 97 percent of this background radiation comes from natural sources (cosmic rays, radon gas and radioactive atoms in the upper atmosphere).
We understand your concern about a lifetime's accumulated exposure to radiation. That's a valid point, but there are bigger sources of exposure that you can control (like opting for MRIs instead of CT scans, if possible). If having a dental X-ray every couple of years reveals an infection or disease — periodontal disease can damage your heart and worsen diabetes — we think the rewards far outweigh the risks.
Q: I've always been active, and I don't eat any more than I used to, but year after year (I'm 65 now) I gain a few pounds! Why does that happen?
— Elsie K., Fort Wayne, Ind.
A: There are a lot of possible explanations. Your metabolic rate may have slowed, in large part because you're not expending as much physical energy as before. And your eating habits may have changed. Have you gotten tired of cooking, so you're eating prepared foods or going out? That amps up calorie intake right away. You also may be insulin-resistant and not know it, which can make you vulnerable to an increased appetite and packing on a few pounds. Ask your doctor to check and see if any other health issues are affecting your weight. But if there are no hidden factors, your weight gain may have to do with the color of your fat.