According to the International Society for Microbial Ecology, cigarettes alter the mouth’s microbiome, which changes the way bacteria break down toxins. This inevitably leads to tooth decay and other oral disease. The human mouth contains over 600 species of bacteria and it is believed that 75% of all oral cancers can be linked to cigarettes and smoking.
Results from a study conducted by the American National Institutes of Health and the American Cancer Society suggest that the oral microbiome of smokers is significantly different from those who have never smoked or are no longer smoking. In the mouths of smokers, the levels of 150 bacterial species were significantly higher, while levels of 70 other species were distinctly lower.
Proteobacteria made up 4.6% of overall bacteria in the mouths of smokers, compared with 11.7% in non-smokers. Proteobacteria are thought to play a part in breaking down the toxic chemicals introduced by smoking.
By contrast, 10% more species of Streptococcus were found in the mouths of smokers, compared with non-smokers. Streptococcus is known to promote tooth decay.
In terms of the time it takes for the bacteria in one’s mouth to return to normal once a person quits smoking, scientists are still conducting tests to find a definitive answer. In the meantime, doctors recommend quitting smoking. For advice on quitting smoking, visit: https://www.ontario.ca/page/support-quit–smoking.