THE MAGIC POWERS OF SALIVA


“Saliva is to tooth enamel what blood is to the cells of the body” – Stephen J. Moss DDS MS

Dr. Lara Coseo DDS, FAGD – Author – 2004 graduate of Baylor College of Dentistry in Dallas, Texas. Having practiced general dentistry for 13 years, Dr. Lara currently serves as an Associate Professor at Texas A&M College of Dentistry.


The Essential Functions of Saliva
Do you know how important your saliva is?  Most people do not.  Unfortunately, many people don’t know what they’ve got until it’s gone.  Sufferers of dry mouth can affirm our strong assertions that good salivary function is essential to a healthy mouth.
Saliva is much more than just water. In this article, we will explain the many important roles saliva plays in a healthy mouth. 

IMMUNITY
There are two important ways saliva functions in the body’s natural defense system, or immunity.  The salivary glands contain plasma B cells that make IgA antibodies.  This antibody performs an important function in protecting the delicate tissues lining the inside of the mouth by binding the mucus layer and keeping dangerous microorganisms from penetrating.
Saliva also assists our immune systems by protecting us from having exaggerated responses to the proteins found in our food.  Some of these proteins are antigens to which the immune system would naturally react, but they are actually harmless.  In order to stop an unnecessary inflammatory reaction that could damage our mouths, the salivary glands produce cells that tightly regulate and suppress the immune system.
ANTIBACTERIAL ACTIVITY
Our mouths are full of bacteria, both good (healthy and not responsible for dental diseases) and bad (pathogenic, causing dental disease).  Saliva contains powerful enzymes that can break down bacteria, preventing an overgrowth of these microorganisms in the mouth.  Lysozyme is an enzyme that breaks down bacterial cell walls.  Lactoferrin is a protein in saliva that prevents bacteria from using iron, which they need to cause disease.  Saliva also contains antimicrobial peptides, which can attach to bacterial cell walls and open large pores, causing the vital cellular fluid to seep out and the bacteria to die.
The antibacterial activity of saliva is noticed most obviously when it is absent.  Patients who suffer from a lack of saliva and a dry mouth tend to have large accumulations of dental plaque and a higher prevalence of the gum disease and cavities these bacteria cause.
BUFFERING
Enamel is the hardest substance in the human body, so the fact that bacteria can penetrate it and turn it to mush (decay) is actually kind of amazing.  The mechanism through which these bacteria break through enamel is the production of a strong acid.  Just as acid can etch a piece of glass, it can soften and weaken enamel, enabling the microorganisms to infiltrate inside the tooth.  The food we eat provides fuel for the bacteria to make this acid.
One of the ways saliva fights tooth decay is through a buffering of the pH inside the mouth.  When we chew food, the body produces more saliva to naturally counteract the acid being made by the bacteria.  Saliva is neutral or just a bit alkaline in pH.  This ability to neutralize acids is a valuable weapon in the fight against cavities.
Studies on patients without adequate salivary flow show that the pH in their mouths stays at an acidic level far longer than in a mouth with good salivary production.  A lingering acidic pH weakens the teeth and increases the risk for cavities.
LUBRICATION
The oral cavity is full of many moving parts that must work together for normal speaking and eating.  The movement of the lips, cheeks, and tongue during normal function requires lubrication inside the mouth.  The soft tissues inside the mouth must slide over the teeth without sticking.
This is both protective and functional.  The lubrication of the soft tissues prevents frequent injuries from the movement of the teeth.  Patients with dry mouth commonly bite their lips, cheeks, and tongues.  The friction between teeth and soft tissues in a dry mouth also result in painful mouth sores and ulcers.
Good lubrication is also necessary for proper speech and eating.  In order to form normal sounds when speaking, you must be able to freely move your lips and tongue without sticking.
0.5 – 1 Litres

The amount of saliva your mouth produces in a single day
TASTE
The human mouth has taste buds all over, and saliva is the vehicle that gets food molecules to those taste buds.  On the tongue, the taste buds are sensory cells located on the tiny bumps (known as papillae).  Saliva’s liquid consistency delivers the tiny molecules of food particles to those sensory cells.  
Without saliva, your ability to taste is depressed.  Unfortunately, many people compensate by eating diets that are high in salt or sugar.  Increasing your salt and sugar intake actually dehydrates you even more, so this can become a vicious cycle!
DIGESTION
When people think of digestion, they tend to begin with the stomach.  The truth is that digestion starts in the mouth!  This first stage of digestion actually occurs on both a large and small scale.  On a large scale, the mechanical forces of chewing physically break large food particles down into smaller ones that you can swallow.  This step of macrodigestion prevents choking.  It also incorporates saliva into the food you are chewing.
On a microscopic scale, saliva contains enzymes that break down the molecules in food to present your stomach and intestines with particles that are easier to digest.  This improves your body’s ability to absorb nutrients from the gastrointestinal tract and keeps you healthy!
INTEGRITY OF TEETH
Did you know that saliva actually makes teeth stronger?  Saliva is responsible for the ever-important process known as remineralization.  The continual attacks of acid from the foods and beverages we ingest and the bacteria in dental plaque soften and weaken tooth enamel by demineralizing it.  Demineralization means that the enamel loses the hard minerals that make up its hard, protective shell.  Demineralized enamel is soft, weak and susceptible to infiltration by bacteria.  
The good news is that demineralization is reversible!  We have the ability to remineralize enamel, and our saliva is the most important tool in our arsenal.  
Saliva aids in remineralization by neutralizing the acid produced by bacteria (discussed earlier in the Buffering section) and by bringing essential minerals to the tooth for reincorporation.  When you drink fluoridated water, your saliva is the carrier of that fluoride to the tooth’s surface.  During remineralization, the enamel surface takes up fluoride, calcium and phosphate minerals from the saliva to re-harden and strengthen the tooth.

3 Ways To Stimulate Saliva
  • Keep yourself well hydrated. Drinking plenty of water encourages a health supply of saliva.
  • Chew xylitol gum to increase saliva flow rate.
  • Snack on healthy foods like vegetables, cheese and nuts.
Dr. Lara Coseo

Dr. Lara Coseo, (DDS, FAGD) is a 2004 graduate of Baylor College of Dentistry in Dallas, Texas. Having practiced general dentistry for 13 years, Dr. Lara currently serves as an Associate Professor at Texas A&M College of Dentistry.


Research

→ Clinical Implications of Recent Advances in Salivary ResearchThis article explores salivary research in an attempt to better understand cosmetic restoration failure.

→ The composition, function, and role of saliva in maintaining oral health:
A review of the components of saliva and their relationship to oral health.

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