Submandibular sialolithiasis is the formation of calcified masses, known as sialoliths or salivary stones, within the submandibular salivary gland or its main drainage tube, the Wharton’s duct. Sialoliths are the most frequent disorder affecting the major salivary glands, constituting 80 to 90% of all reported cases. Although benign, the obstruction causes painful, recurrent swelling and inflammation, significantly impacting quality of life. Management strategies range from simple conservative measures to highly effective, minimally invasive procedures.
Why Salivary Stones Form
Salivary stones are primarily composed of inorganic mineral salts, specifically calcium phosphate (hydroxyapatite) and smaller amounts of calcium carbonate. These minerals precipitate around a microscopic central core, or nidus, typically made up of organic debris like shed ductal cells or concentrated mucus. Layered deposition of mineral salts causes the stone to grow over time, eventually creating a physical obstruction.
The submandibular gland is susceptible to stone formation due to specific anatomical and physiological factors. Its saliva is significantly more viscous and mucinous compared to other glands, and it contains a higher concentration of calcium. Furthermore, the Wharton’s duct is long, features two natural bends, and requires saliva to flow against gravity to exit into the mouth. These factors promote salivary stagnation, or stasis, which is the primary mechanism leading to mineral precipitation and stone growth.
Certain systemic factors also predispose individuals to sialolithiasis by reducing salivary flow. Dehydration concentrates the saliva, making mineral precipitation more likely. Similarly, some medications, such as antihistamines, diuretics, and certain antidepressants, reduce the overall volume of saliva produced, exacerbating stagnation.
Recognizing the Signs
The defining clinical sign of a submandibular sialolith is painful, recurrent swelling beneath the jaw or in the floor of the mouth. This consistent symptom pattern is often described as the “meal-time syndrome.” The swelling and pain worsen dramatically during or immediately after eating, or even with the anticipation of food, because eating stimulates a sudden surge in saliva production.
When saliva attempts to rush past the stone, it creates a back-up of fluid, which rapidly distends the gland and causes painful pressure. The pain typically subsides over a few hours as salivary flow decreases or as built-up saliva slowly leaks past the obstruction. Other symptoms may include a dry mouth or an unpleasant, foul taste if the stone only partially obstructs the duct. If the obstruction leads to a secondary bacterial infection (sialadenitis), the patient may experience more severe signs like fever, redness of the overlying skin, and pus draining from the duct opening.
Confirming the Diagnosis
Diagnosis typically begins with a physical examination, where a healthcare provider may be able to feel the stone directly. Stones located close to the duct opening in the floor of the mouth are often manually palpable. However, imaging is essential to accurately confirm the presence, size, and precise location of the stone, especially those lodged deeper within the gland.
A non-contrast computed tomography (CT) scan is the gold standard for definitive diagnosis due to its high sensitivity in detecting calcified structures. For stones located anteriorly in the duct, a plain film X-ray (occlusal view) can visualize the stone, as 80 to 90% of submandibular sialoliths are radiopaque. Ultrasound is a non-invasive, radiation-free option effective for identifying stones larger than three millimeters and assessing ductal dilation. Sialendoscopy, which involves inserting a tiny scope into the duct, is used for both diagnostic purposes and confirming the exact anatomy and pathology of the ductal system.
Treatment Options
Management of submandibular sialolithiasis follows a step-wise approach, starting with conservative measures. Simple strategies focus on encouraging the natural passage of the stone by increasing salivary flow and reducing inflammation. Patients are advised to increase fluid intake, apply moist heat, and gently massage the gland to manually push the stone forward. Using sialogogues, such as sour candies or lemon drops, stimulates a strong flow of saliva that can sometimes flush small stones out of the duct.
If conservative measures fail, minimally invasive techniques are considered next to preserve gland function. Sialendoscopy is a common approach where a miniature endoscope is inserted into the duct, allowing the surgeon to visualize and remove smaller stones (up to five millimeters) using a wire basket. For slightly larger stones (five to seven millimeters), sialendoscopy can be combined with intraductal laser lithotripsy, where a laser fiber fragments the stone into smaller pieces for irrigation or removal. These gland-preserving methods boast high success rates, with gland preservation rates exceeding 95%.
Traditional surgical options are reserved for stones that are too large, too deeply impacted, or when the condition has severely damaged the gland. For stones located anteriorly in the duct, a transoral duct incision, or sialolithotomy, allows for direct surgical removal through the mouth. When all other treatments fail, or for very large stones situated deep within the gland, the final option is a submandibular gland excision (removing the entire gland). The advent of modern, minimally invasive techniques has drastically reduced the need for this major surgery, with the rate of gland removal now falling below five percent of all cases.