A one-pack-a-day smoking habit can cost you the loss of at least two teeth every 10 years, reports the Academy of General Dentistry (AGD).

Smokers are about twice as likely to lose their teeth than non-smokers, according to the results of two separate 30-year studies that investigated the relationship between smoking and tooth loss among males and females at Tufts University in Boston.

In one study, 495 healthy men had their teeth examined every three years. The men were divided into three groups: those who never used tobacco products, those who continuously smoked and those who smoked at the beginning of the study but later quit. Smokers lost an average of 2.9 teeth after 10 years of smoking one pack a day, while non-smokers lost an average of 1.3 teeth after 10 years. In men who quit, the tooth loss was 2.4 teeth after 10 years of smoking one pack a day, and this decreased to 1.7 lost teeth after they quit.

"The good news is that the risk of tooth loss decreases after you quit smoking," says AGD spokesdentist Fred Magaziner, DDS, MAGD. "But the bad news is that the risk of tooth loss was still higher among the quitters than among those who never smoked."

Another study at Tufts University, which looked at 583 healthy postmenopausal women, and found that female smokers were twice as likely to lose one or more teeth every 10 years than non-smokers, and that the risk of losing teeth decreases among women who quit smoking.

"The bottom line is that smoking leads to periodontal (gum) disease, which leads to tooth loss," says Dr. Magaziner. "Smoking causes a chain of events in the mouth that eventually leads to tooth loss. The chain starts with plaque build-up on teeth, which is linked to tartar build-up (an even harder, yuckier substance on the teeth), which can cause gingivitis. From there, you step up to periodontal disease, and the final destination is tooth loss."

The chain can be broken by brushing and flossing regularly and by stopping the use of tobacco.

If you start smoking at age 18 and smoke one pack a day, how many teeth will you lose by the time you are 35 years old?

Answer: Between four and five teeth. The Academy of General Dentistry reports tooth loss due to smoking at the rate of 2.9 teeth every 10 years for men and 1.5 teeth every 10 years for women.