A recent study linking dental X-rays to a usually non-cancerous form of brain cancer is, of course, alarming. It should not, however, be taken as a reason to stop going to the dentist or to abandon all use of the diagnostic tool.

The study in the journal Cancer shows that people who have had dental bitewing X-rays in the past are more likely to develop a type tumor called meningioma than those who have not. It does not prove, researchers say, that dental X-rays cause tumors, but supports earlier studies that there is a connection between the two. In addition to brain tumors, dental X-rays have been linked to thyroid cancer. The report should prompt individuals to talk to their dentists about the necessity of X-rays before routinely agreeing to have them.

The study is not definitive. Researchers talked with nearly 1,500 patients who had meningiomas and compared those individuals with 1,350 people who did not have tumors. They asked both groups about their dental X-ray history. They found that those who had brain tumors were twice as likely to have had X-rays as those who did not.

The study, though, was not rigorously controlled. It relied on people's memory of how many X-rays they had over the course of years rather than empirical proof. Moreover, there was no way to accurately measure radiation exposures. The latter is especially important since X-rays employed decades ago exposed patients to far more radiation than those used today. More exacting studies clearly are needed

For the moment, experts still recommend that children have dental X-rays about every one or two years; that adolescents have them every 18 months to three years; and that adults do so every two to three years. Those guidelines, experts say, should help minimize the effects of radiation. Reducing such exposure should always be the goal, whether the X-rays are used for dental or medical procedures.

Some people might seize upon the study as a convenient excuse to avoid a trip to the dentist. That would be a mistake. Dental care is important to overall health. Rather, the study should encourage greater understanding of the benefits and possible dangers of dental X-rays.