The human mouth is full of bacteria, viruses, fungi and even rotting food, but people rarely get sick because of those things because saliva also has antibodies and antimicrobial compounds that can destroy bacteria and viruses. Saliva also has calcium and phosphate ions, which help keep the teeth from being destroyed by the acidic environment required for digestion. In fact, saliva can even re-mineralize small damaged spots on the teeth.
Other health benefits of saliva:
- Despite all the potentially harmful things in the mouth, it's more dangerous for a person to get bitten or cut by someone else's teeth than it is to bite his or her own tongue or cheek because of all the protective components in saliva. People who are seriously bitten by humans often need a tetanus booster, antibiotics and sometimes medication to decrease the risk of disease transmission. Although many bites are harmless, if left untreated, a serious bite can cause permanent damage or even sepsis, which occurs when too much bacteria gets in the bloodstream.
- Saliva also promotes wound healing in humans and in some animals. Cuts to cheeks and gums heal more quickly with less scar tissue than cuts on other parts of the body in humans. Mouse saliva has a protein that, when spread on its wounds, helps the wounds heal twice as fast as non-treated wounds.
- Saliva doesn't just protect the mouth — it appears to protect the upper digestive tract as well.