Saliva! What is it good for? A lot more than wetting the backs of postage stamps. Though it’s true that spit is useful stuff outside the mouth, the real wonder of it is what it does in its native habitat. In this post we’ll review where saliva comes from, and what it’s made of. We’ll discuss the many good things saliva does for us. Then, we’ll look into the things that go wrong with it. We’ll pay special attention to the common disorder called xerostomia, or dry mouth. Causes, symptoms, complications, and remedies.
THE SOURCES OF SALIVA
A set three pairs of glands in our mouths account for most of our saliva production. These are located in the cheeks and under the tongue. Hundreds of much smaller glands add to the flow. They’re all exocrine glands, the same general type as sweat and mammary glands. The flow is quite impressive. People produce between a pint to a quart and a half of saliva daily.
Our production of saliva is controlled by the autonomic ( involuntary) nervous system. Hence, we don’t have to think about salivating it or “command” it. It’s automatic. There are ways a person can wilfully increase production, but normally it’s self-regulating.
Some of the things that trigger the production of saliva are common knowledge. We speak of an appealing supper entrée as “mouth-watering”. Yes, sights and smells of food set off a chain reaction in the brain that stimulates saliva glands. The saliva these then secrete is relatively watery. Its purpose, of course, is to aid in digestion.
In addition, there’s a thicker, more mucous-loaded type of saliva, too. Its job is to protect and lubricate the delicate tissues of our airways. Production of the two types of saliva is controlled by two different “channels” of the nervous system. One channel is stimulated by food-related sensations, and the other by other physiological triggers. The saliva glands have two types of cells, each producing one of the types of saliva.
WHAT IS SALIVA MADE OF?
The main ingredient in saliva is, of course, H2O. Water, that is. In fact, saliva is almost entirely water, 99.5%. Since an average healthy adult produces over a quart of it daily, we have to replace that water by drinking. In any case, it’s the other 0.5% of ingredients that are most interesting. The group of substances that together are just 1 part in 200 of saliva.
It is an interesting set of micro-ingredients, indeed. At least 8 electroytes, including calcium and iodine. Three major enzymes, and a dozen or more minor ones. There’s natural painkiller (opiorphin) which works by enhancing the activity of our natural opiods in the spinal cord. Opiorphin, milligram for milligram, is more powerful than morphine! Rounding out the ingredients list are growth hormones, various antibiotics and proteins, and mucuous. Moreover, our nervous system controls the make-up of this mix in response to changing circumstances. Our saliva glands are actually sophisticated chemistry and biotech labs!
WHAT DOES SALIVA DO FOR US?
The length and variety of the ingredients list for saliva is a tip-off as to the roles it fills. The two general body functions that saliva supports are respiration (breathing) and digestion.
As noted earlier, glands secrete a thicker, more mucousy type of saliva to support respiration. Think about the very soft, raw linings of your nasal passages, throat, and windpipe. In order to stay healthy, these tissues need coating and lubrication. That’s what the thicker type of saliva provides. Under some conditions (strenuous activity, cold dry air, etc.) glands need to make more of it. They do, automatically.
Broadly speaking, chewing is a the first step in the process of digesting food. Therefore, we’ll consider saliva’s roles in keeping teeth and gums healthy as digestive support. Saliva does naturally what we accomplish ( more effectively, to be sure) by brushing and flossing.
First, saliva rinses teeth and gums. It dislodges food debris and sloshes it down the “drain” to our stomachs. Saliva’s natural antibiotics act against the very bacteria that cause tooth decay, cavities, and gum disease. It rennovates tooth enamel with its calcium and phosphates, while controlling mouth acidity for best results. Saliva delivers Epidermal Growth Factor (EGF) to the gums, which kicks up growth of new gum cells.
So saliva is pretty amazing stuff. We produce more or less of it according to what’s going on at any given moment. When we sleep, for example, we produce little or none. Moreover, we change the composition of our saliva in response to changing conditions. All this goes to keep our airways moist and comfortable, our digestion smooth, and our teeth and gums healthy.
So what happens when something goes wrong with this system?
TOO MUCH SALIVA: DROOLING
Saliva is good stuff, but as with many good things, more is not necessarily better. There’s such a thing as too much. When we make too much saliva, we can find ourselves drooling. This happens in a number of ways. Other things going on in our bodies, such as acid reflux, can stimulate saliva production beyond our actual needs for it. Pregnancy sometimes stimulates saliva production to excess.
TOO LITTLE SALIVA: DRY MOUTH
Xerostomia, or in everyday terms “dry mouth”, results from under-production of saliva. The main symptom of this condition is – can you guess? – a dry mouth. Nearly all of us have experienced that at one time or another. When it’s the real thing, though, a dry mouth comes with other discomforts. Think back to that list of respiration and digestion functions saliva supports. Without this support, your voice becomes hoarse. You have trouble swallowing and chewing. Your tongue turns to sandpaper and is tender. You may even develop sores, or cracks in your lips. Not at all comfortable. As a matter of fact, it’s just plain unhealthy. We need to be at the top of our game when it comes to breathing and digesting.
CAUSES OF DRY MOUTH
There are a number of paths that lead to dry mouth. Can you guess the most common? Remember the observation that the average adult produces over a liter of saliva daily? That saliva’s 99.5% water? Well, if we simply don’t have that water available in our bodies, we can’t make spit. Dehydration’s the most frequent cause of dry mouth. There are lots of ways we get dehydrated, but they all boil down to the same equation. If we take in less water than we put out (sweating, salivating, urinating, etc.) we get dehydrated.
Aging is related to dry mouth, too. There seem to be several connections. In addition to simply getting older, aging tends to come with a variety of conditions (like rheumatoid arthritis) that by themselves cause dry mouth. Aging often means taking more medications on a regular basis, too. Turns out hundreds of common meds are culprits in causing dry mouth.
A dizzying variety of medical conditions and even recreational drugs ( such as alcohol and marijuana) round out the list of saliva suppressors. It begins to seem like a miracle we don’t all have dry mouth all the time!
DEALING WITH DRY MOUTH
Drooling isn’t pretty. It may be a sign of something more serious going on, but otherwise it’s basically a cosmetic issue. Dry mouth, in contrast, is inherently unhealthy. When it’s more than just a short, passing thing, we need to do something about it. Otherwise, we’re at increased risk of tooth decay, gum disease, cavities, and worse.
Your Orlando dentist is your go-to resource for diagnosing and treating dry mouth. Xerostomia falls squarely in the domain of dental practice. Dentists know how to treat it, and know when to refer patients to other specialists when necessary. In the many patients for whom treatment won’t work, dentists help patients adapt. There are ways make up for a lack of saliva and cover the same bases it does.
The key thing for patients is to speak up. Over time, dry mouth leaves signs that dentists identify during checkups. However, the condition can persist for some time, and many months pass between routine checkups. Patients concerned about dry mouth should take the initiative. Don’t stay dry, don’t be shy. Call your dentist.