If you listen to comedy, or even just to your friends and relatives, you may hear something unpleasant compared to a root canal. Someone might joke, "I'd rather have a root canal" when turning down an offer or request. No one ever says they actually want root canal treatment. But if you're a smoker, that's essentially what you're doing whenever you put a cigarette in your mouth.

Root canal treatment defined

Root canal treatment becomes necessary when the inner layer of the tooth, called the pulp, becomes infected or inflamed. The pulp contains nerves and blood vessels. It fills the center of the tooth, from the crown, which is the part of the tooth we see above the gumline, down through the canals in the roots of the tooth.

To prevent the infection from spreading to the jaw and the rest of the body, we treat it by cleaning out the infected pulp and then filling the canals. With modern anesthetics and techniques, it's a generally comfortable procedure that relieves pain and saves the tooth.

The link to cigarettes

A study published in the April 2006 Journal of Dental Research established a link between cigarettes and the need for root canal treatment. Conducted by researchers from the Boston Veteran's Administration Hospital, the study tracked the oral health of 811 men over the course of 30 years.

In addition to noting the tooth decay, periodontal disease, fillings or other restorations, and the men's oral hygiene routines, researchers looked at the men's smoking history and how many teeth had been given root canal treatment. What they found is that the smokers had a significantly higher rate of having root canal treatment than nonsmokers.

The bad news

At the beginning of the study, 18,893 teeth were free of root canal treatment. At the end, researchers identified 998 teeth that had received root canal treatment during those 30 years. The data results were then measured against the men's smoking habits.

Researchers discovered 3 significant facts about smoking and the risk for root canal treatment:

• Cigarette smokers on average are 70 percent more likely to need root canal treatment than nonsmokers.
• Men who have smoked between 5 and 12 years are 100 percent more likely to need treatment. That means they have double the risk that nonsmokers have.
• Smokers with more than 12 years have an even higher risk (102 percent).

Scientists don't yet know why this correlation exists between smoking and root canal treatment. It could be several factors. Smoking reduces the body's ability to fight infection, so when a tooth's pulp becomes irritated, a smoker's immune system may not be able to prevent it from developing into inflammation or infection. Other studies have suggested that tobacco is strongly associated with tooth decay, and a cavity that reaches the pulp of a tooth is a common gateway for bacteria to get into the pulp and infect it.

Another reason may be revealed by a recent study that was statistically representative of American adults. It found that smokers are much less likely to get dental care than nonsmokers, even though smokers are at greater risk for many kinds of oral health problems, including gum disease, tooth loss, and oral cancers.

The good news

The Boston VA study also offers hope. It indicates that you can help protect the health of your teeth by quitting. Men who had been smokers, and then quit and stayed smoke-free for 9 years, were no more likely to need root canal treatment than men who had never smoked.

If you're a smoker, there's only one word for you: quit. Besides preventing the need for root canal treatment, there are compelling reasons having to do with oral health alone: oral cancer, buildup of tartar and plaque on the teeth, bad breath, stained teeth, and increased risk for tooth decay, periodontal disease, and tooth loss.