If you knew just half of what saliva does for you, you’d be a lot less inclined to think of it as disgusting, or even to call it “spit.” Those who have ever experienced dry mouth (xerostomia) certainly have a greater appreciation for it. They have firsthand experience of the importance of saliva because it has an impact on their ability to chew, swallow, and even talk. As the song says, “You don’t know what you’ve got until it’s gone.”
Few people – even those who have experienced dry mouth – understand just how amazing saliva and the salivary system really are. From your grade school science classes, you probably recall that it is important to digestion, but you may think it does nothing more than “wet down” the food. You may be more inclined to know the bad things about it – such as its ability to spread bacteria or disease – than you know about the good things. These are just a few of the interesting complexities that dentists and doctors know and appreciate about saliva.
- Saliva is the supply chain for maintaining and rebuilding tooth enamel. Your tooth enamel is much like the protective coating on a heavily used piece of furniture; it’s going to wear away, particularly if it softens. Saliva is full of minerals that are constantly being used to restore the surface of tooth enamel. It is depositing calcium and phosphate that helps your tooth enamel grow harder. When you brush your teeth with fluoride toothpaste, the amount of fluoride in saliva increases and floats onto teeth where it readily combines with calcium ions that are present there. Together, they create a protective barrier on the surface of tooth enamel that helps it resist acid attack.
Children are more prone to tooth decay than adults simply because their enamel has not had the opportunity to undergo this mineralization and hardening process as long. If you’re a bit older, you may not realize that the tooth enamel you have today is not at all the same tooth enamel (the same atoms) that you had 20 years ago. Saliva, then, is one of the most important decay preventing agents there is because it builds strong enamel. (Parents, that’s just one more tidbit to help you teach children not to spit on sidewalks. Our mouths really need that saliva!)
- Saliva is a critical part of your body’s immune system. Too often we think of saliva as being a way of transferring disease to other people. Just like saliva is an important transport system for the minerals that build tooth enamel, it carries many immunoproteins that prevent microbes from overtaking your mouth. Some immunoproteins cause bacteria to aggregate (clump together) so they can be more easily washed away. There are other immunoproteins that work very hard to prevent specific types of oral disease, such as gingivitis. When your gum tissue becomes inflamed, these immunoproteins are produced and released in the saliva, where they go to work trying to prevent the onset of gingivitis. (A word of caution – don’t expect your saliva to “go it alone” in combating gingivitis – you have to do your part to keep your teeth and gums clean, too.)
- Saliva is an acid neutralizer. While saliva has a pH that is similar to that of water, when acid is present in the mouth, it goes to work to help neutralize acid – whether it is being ingested (orange juice, lemonade, sodas) or from internal sources such as acid reflux. (Once again, that does not mean your saliva can “go it alone.” You need to moderate your intake of acidic substances and seek treatment for acid reflux disease.)
- Saliva is providing new insights into bodily health. While you might be familiar with the use of saliva for drug testing and DNA testing, you might not know what other insights it is providing. The “beauty” of testing saliva is that collecting it is a simple and non-invasive procedure. It is easy to test once, as well as retest to detect changes that are occurring from test to test. It is commonly used to test for viral infections such as HIV, but there is great promise for its use in diagnosing oral cancers, breast cancer, and hepatitis. Many such tests are currently undergoing clinical trial.
Hopefully, this has helped you change your attitude about saliva. To call it “spit” is to spit in the face of all that it does and might do for you in the future!