The Academy of General Dentistry (AGD) reports that a pack-a-day habit can cause some smokers to lose at least two teeth every 10 years. So, if you started smoking a pack a day at 18 and are now 35, you may be missing a few of your pearly whites.

In one study, 495 healthy men had their teeth examined every three years. They were divided into three groups: those who never used tobacco, those who smoked continuously, and those who smoked at the beginning of the study but later quit.

After 10 years, the pack-a-day smokers lost an average of three teeth, while nonsmokers lost an average of one. The men who smoked at the start of the study, but later quit, lost an average of two teeth after 10 years, and tooth loss declined after that.

"The bottom line is that smoking leads to periodontal disease, which leads to tooth loss," says Fred Magaziner, D.D.S., spokesman for the AGD.

If you've tried to quit, but have had trouble, check out the "Ideas for Smokers" and "You Can Quit Smoking" information from the federal government's Agency for Health Care Policy and Research (AHCPR). Their information discusses the most effective ways to quit, such as nicotine patches, nicotine gums, and learning ways to channel stress.

AHCPR Smoking Cessation Information