ZIMBABWE’S population is largely rural (60%), with the remaining 40% residing in urban areas.
Public health experts observe a significant “tooth puller” perception among the rural population, the belief that a dentist’s primary role is merely tooth extraction.
In contrast, roughly 60% of urbanites have embraced dental literacy, understanding that dentists also perform fillings, root canals and various other restorative procedures.
Despite these differences, both groups share a common misconception: they associate oral health strictly with brushing, flossing and avoiding cavities. However, oral health is far more complex.
Eating, swallowing, speaking and even sleeping without your tongue sticking to the roof of your mouth are all made possible by an often-forgotten system: The salivary glands.
A wise man once said, “Wealth is what you do not see.” We rarely see our salivary glands, but their importance to our survival is immense. The question is: to what extent?
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What are salivary glands?
Salivary glands are a network of specialised tissues that produce nearly 1,5 litres of saliva everyday.
In fact, besides urine, saliva is the most abundant fluid produced in the human body. While production peaks at mealtimes and reduces significantly during sleep, your body never truly stops making it.
Over an average 70-year lifetime, a human will produce roughly 25 000 to 30 000 litres of saliva, enough to fill two Olympic-sized swimming pools.
There are three main players (the major salivary glands) that work alongside hundreds of microscopic minor glands scattered throughout your lips, cheeks and palate:
The parotid glands: Located in front of each ear. Though not visible to the naked eye, they are the largest glands and the most common site for viral infections like mumps.
The submandibular glands: Located under the jawline. They produce the thickest saliva and are the most common site for salivary stones (calcified blockages).
The sublingual glands: Located directly under the tongue.
Saliva is composed of approximately 98% to 99,5% water. The remaining fraction is a potent cocktail of electrolytes, mucus, white blood cells, enzymes (like amylase) and antimicrobial agents. This tiny percentage of ingredients is what makes saliva so valuable; without them, it would be mere water.
Functions of saliva
The first step of digestion
Digestion does not begin in the stomach; it starts the moment food enters the mouth.
Saliva contains amylase, an enzyme that breaks down complex carbohydrates (like the starch in sadza or bread) into simple sugars.
This is why bread begins to taste sweet if chewed long enough. Furthermore, saliva acts as a lubricant, binding food particles into a soft, slippery mass called a bolus, allowing it to slide down the esophagus safely. Without saliva, swallowing dry food would feel like swallowing sandpaper.
The sense of taste
You cannot taste dry food. Taste buds are tucked away in the grooves of the tongue and can only detect chemicals that have been dissolved in liquid. Saliva acts as the solvent that carries food molecules to these receptors. Without it, a piece of chocolate and a piece of cardboard would taste remarkably similar.
The natural “dentist” (Remineralisation)
Above all, in oral health, the most critical role of saliva, especially in the context of Zimbabwe’s dental health landscape, is its ability to repair teeth.
Every time we eat, normal bacteria in our mouths ferment the sugar to produce acid.
This acid dissolves the minerals in our tooth enamel, a process called demineralisation, as explained in the previous article.
The acid lowers the pH in the mouth to the critical state, which is conducive for bacteria to multiply and to produce more acid.
In this case, saliva works as the body’s natural counterattack by helping with the washing away of this acid.
Saliva acts as a buffer. It has different buffer systems, but the most important one to help with neutralisation of the acid is the bicarbonate buffer, which helps to keep the mouth at a pH level that is safe for the enamel.
Without this buffering capacity, the "urban diet" of processed sugars and sodas that we consume would destroy our teeth at a continuous and uncontrollable rate.
Additionally, saliva is rich in calcium and phosphate ions. When the pH level in the mouth returns to normal, saliva bathes the teeth in these minerals, rebuilding the microscopic holes in the enamel. This is known as remineralisation.
The immune guard
The mouth is the primary gateway for pathogens. Saliva serves as the first line of immunological defence, containing Secretory Immunoglobulin A (sIgA), an antibody that hunts viruses and bacteria.
It also contains lysozyme, which bursts the cell walls of harmful bacteria and lactoferrin, which starves bacteria of the iron they need to grow. Your mouth is essentially a chemical laboratory, constantly "sanitising" itself to protect your lungs and gut.
When the well runs dry: The danger of Xerostomia
The importance of saliva becomes most obvious when it disappears. Chronic dry mouth or Xerostomia, can be devastating. In Zimbabwe, this is frequently seen in patients taking blood pressure medication, those undergoing treatment for HIV/Aids or the elderly. When saliva production fails, the results are severe:
Rapid tooth decay: Cavities form in months rather than years, often appearing aggressively along the gum line.
Oral Candidiasis: Without protective enzymes, fungal infections like thrush thrive.
Difficulty speaking: Without lubrication for the tongue and lips, clear speech becomes physically exhausting.
We must remember that oral health is not just about the teeth we see, but the invisible fluids that keep them alive.