LAST week, we explored the "invisible wealth" of our salivary glands: the silent network of tissues that produces nearly 1,5 litres of life-sustaining fluid everyday. We established that oral health is not merely a matter of "hard tissue" like teeth and bone, but a fluid-driven system.
However, like any complex machinery in use, this system is prone to mechanical failure and biological threats.
In the second part of our series, we move from the protective functions of saliva to the pathologies that occur when the glands themselves become the site of disease.
Specifically, we look at the mechanical "drought" caused by sialolithiasis and the difficulty of diagnosing salivary gland tumors and whether it is necessary to do so.
Sialolithiasis: The "kidney stones" of the mouth
While many people are familiar with the pain of a toothache, there is a specific, agonising pressure that occurs under the jaw or in the cheek, often triggered by the mere smell of food. You enter the kitchen, and a food scent hits you before you've taken a bite, and the pain comes immediately. Some may ask how the smell of food is related to pain in the mouth. If we think too deeply about it, we will consider it strange, but here is the answer to why.
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What causes the pain is a condition called sialolithiasis or salivary stones. These stones are not similar to the ones we see on the sidewalk; they were called stones because of their shape and hardness. In oral health, stones are calcified structures formed from the very minerals calcium and phosphate that saliva uses to protect our teeth. When saliva becomes stagnant or overly concentrated, these minerals crystallise, forming a stone that can block the narrow exit ducts or passage of the glands.
Why the submandibular gland?
Interestingly, 80% of these stones occur in the submandibular gland (located under the jawline). There are two biological reasons for this:
Anti-gravity ascent: The duct for this gland, known as Wharton’s duct, must travel upwards to reach the floor of the mouth. Saliva essentially has to climb a hill or move upwards, making it easier for sediment to settle at the bottom.
Chemical composition: Submandibular saliva is more alkaline and has a higher concentration of calcium than parotid gland saliva, creating a perfect environment for stone formation since the stone requires minerals to form.
The 'mealtime syndrome'
The most telling symptom of a stone is swelling that occurs immediately before or during a meal. As the brain signals the gland to produce saliva to aid digestion, meaning that before you have eaten, your salivary glands are already producing a lot of saliva in preparation for digestion. Hence, the fluid builds up behind the blockage, stretching the gland's capsule and causing sharp, radiating pain. In rural communities where diagnostic imaging is scarce, this is often mistaken for a dental abscess or a swollen lymph node. If left untreated, the stagnant saliva can become infected, leading to a feverish, pus-filled condition known as sialadenitis. The salivary stone condition can feel better if antibiotics are taken, antibiotics are not the main treatment decision.
The ‘Painless lump’: Malignant tumors
If stones are a mechanical nuisance, tumors are the silent invaders of the salivary system. In the hierarchy of oral health, a lump that does not hurt is often more dangerous than one that does. Many times, when we see a painless lump, we often conclude that it is not of great concern. This mentality has caused late diagnosis of salivary gland cancers that spread to other organs and eventually caused death.
Salivary gland tumors are relatively rare, accounting for about 3% to 6% of all head and neck neoplasms. However, their diversity makes them a challenge for even the most trained oncologists. There are over 30 different histological types of salivary gland tumors; the diagnosis of these cancers demands a lot of skill and time.
In clinical practice, we often use a general "rule of thumb" regarding the size of the gland and the likelihood of cancer:
Parotid glands: About 80% of parotid tumors are benign (non-cancerous), such as the Pleomorphic Adenoma.
Minor salivary glands: Conversely, if a tumor originates in the small glands in the roof of the mouth (palate), there is a roughly 50% to 80% chance it is malignant.
Identifying malignancy: Red flags
A malignant tumor behaves differently from a benign growth. While a benign tumor is usually a slow-growing, movable lump, a malignancy may show the following aggressive traits:
Facial nerve paralysis: Because the facial nerve (the wire that controls your ability to smile or blink) passes directly through the parotid gland, a tumor that causes sudden drooping on one side of the face is a major red flag for cancer.
Fixation: The lump feels "stuck" to the skin or the underlying bone.
Rapid growth: A noticeable increase in size over a few weeks or months.
Wealth is knowledge: Bridging the literacy gap
As we noted last week, the transition from seeing a dentist as a "tooth puller" to seeing them as an oral physician is vital for Zimbabwe’s public health. In many rural districts, a patient may live with a parotid lump for years, assuming it is a harmless consequence of aging or a curse from the ancestors, only seeking help when the tumor has invaded the jawbone or skin, making treatment and diagnosis difficult.
Teaching patients that "oral health is fluid" means encouraging them to palpate their jawlines and cheeks. It means understanding that a dry mouth is not just thirst and a lump is not just a swelling; it is much more than that.
The modern path to healing
Fortunately, the hidden nature of these glands is becoming more visible through technology.
Sialendoscopy: For stones, we no longer always need to cut. Tiny endoscopes can enter the duct, visualise the stone and retrieve it with a microscopic basket.
Targeted Radiation: For malignant tumors, advancements in oncology allow for the preservation of the facial nerve while aggressively treating the cancer cells.
We must shift the national conversation. Wealth is indeed what you do not see until it is gone. The 1,5 litres of saliva we produce daily are a miracle of biological engineering, but the glands that produce it are vulnerable.
Whether it is the stone blocking the path or the tumor invading the tissue, the solution remains the same: early detection. We must move beyond the tooth-only mindset and realise that the soft tissues and fluids of the mouth are the true gatekeepers of our systemic health.
Next time you enjoy a meal of sadza and greens, remember the complex system working beneath your skin to make that moment possible. Protect the flow and you protect your life as well.