Elizabeth Krall Kaye, PhD, MPH, and colleagues reported their findings in New York, at a media teleconference organized by the American Medical Association and American Dental Association.

"Our study has shown that men have almost twice the risk of having root canal treatments if they smoke cigarettes, compared to men who never smoke," Kaye said, in the teleconference.

Kaye is a professor in the department of health policy and health services research at Boston University's Goldman School of Dental Medicine.

About the Study

Kaye's team got data from a study of 811 men who were followed for up to 28 years. The study started in the late 1960s and early 1970s. Back then, the men were about 48 years old, on average. The men were mostly middle-class whites.

Every three years, the men got their teeth examined and had dental X-rays taken at the study site. The men also reported their smoking habits.

A total of 230 men had never smoked. Another 440 men were former smokers. Most of the smokers smoked cigarettes. Few smoked pipes or cigars.

The researchers checked the X-rays to see if root canals had been done. They spotted 998 teeth that had root canals done on them. Those teeth belonged to 385 men, so many men got more than one root canal.