Smoking wipes out helpful bacteria in your mouth

May 15, 2012

Dentist consulting with the patient

Smoking can do a lot of harm to a healthy mouth and bright smile. Some of the damage is just cosmetic. It leaves ugly stains on teeth and causes bad breath. But smoking can cause more serious problems in the mouth, too.

It greatly raises the risk of oral cancer. It can slow healing after oral surgery. And it contributes to gum disease, a leading causes of tooth loss.

A new study helps explain how it causes these problems. It even suggests something new: Smokers may be more vulnerable to other diseases because of how smoking affects the mouth. It appears to kill off the good bacteria that help fight germs.

The new study was reported in the journal Infection and Immunity. Purnima Kumar, Ph.D., from Ohio State University, described the results. Kumar, who took part in the study, is an assistant professor of periodontology. Periodontology is the area of dentistry that studies structures that support the teeth. These include gums, ligaments, and bones.

How is a healthy mouth like a healthy lawn?

Kumar explained the background for the study. A few hours after you’re born, bacteria start forming communities called biofilms in your mouth. Your body learns to live with them because for most people healthy biofilms keep bad bacteria away.

Kumar compares a healthy biofilm to a lush, green lawn. When you change what goes into the lawn you can upset the balance. Too much water or fertilizer can kill the grass and let weeds move in. For smokers, she said the “weeds” are harmful bacteria known to cause disease.

In the study, Kumar’s team looked at how biofilms regrow after being wiped away. Groups of healthy nonsmokers and healthy smokers took part in the study. Both groups had their teeth cleaned professionally. Researchers took samples of their mouths’ biofilms several times after the cleaning.

The mouths of smokers and nonsmokers were very different

When they compared the mouths of smokers and nonsmokers, there were clear differences. The “lawn,” which normally has strong groups of helpful bacteria, was missing in smokers. Just 24 hours after the cleaning, their mouths showed a higher level of harmful bacteria.

Smokers also had a higher level of cytokines. These are substances the body makes to fight infection. The cytokines were causing red, puffy gums. This condition can lead to serious gum disease. And gum disease is a leading cause of tooth loss.

There was another surprising finding in the study. The cytokines weren’t just attacking the harmful bacteria. They were also attacking the helpful bacteria your body needs to stay healthy.

These new findings give smokers even more reason to kick the habit. A report from the National Center for Health Statistics sums it up. Current smokers are four times more likely than those who’ve never smoked to have poor oral health. And they’re twice as likely to have had three or more oral health problems.

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