Sialolithiasis (Salivary Calculi)
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Direct answer
Swelling of the submandibular region that appears within minutes of eating, aches, and subsides an hour or two after the meal is almost diagnostic of sialolithiasis — obstruction of a salivary duct by a calculus, with the submandibular gland and Wharton's duct hosting the great majority of stones. The explanation for this distribution is anatomical and biochemical: the duct runs uphill against gravity, is long and tortuous, crosses the lingual nerve, and its saliva is mucinous and alkaline with a higher calcium and phosphate content. Stones are usually single and radiopaque far more often in the submandibular than the parotid region, so an OPG or lower occlusal film often shows them directly. Small distal stones release with massage, hydration and sialogogues or are removed transorally; stones locked in the gland with recurrent sialadenitis and gland destruction call for sialadenectomy.
What you must remember
- Distribution: about 80 to 90 per cent of salivary stones form in the submandibular gland or duct, roughly one in ten in the parotid, sublingual and minor glands sharing the remainder — the opening number of every answer.
- Why submandibular: duct long, wide and tortuous, ascending against gravity to open on the sublingual papilla; saliva mucinous, alkaline and calcium-rich; a kink at the posterior edge of mylohyoid slows flow.
- Radiopacity: the majority of submandibular stones are radiopaque and visible on a lower occlusal or OPG; parotid stones are more often radiolucent, requiring ultrasound, sialography or CT.
- Clinical picture: meal-related painful swelling (salivary colic), tenderness of the gland, dry mouth then sudden flooding as the obstruction partially clears; bimanual palpation along the floor of the mouth frequently traps a hard nodule.
- Complications: acute suppurative sialadenitis with fever and purulent papillary discharge, duct stricture after long-standing obstruction, and rarely abscess; chronic recurrent sialadenitis hardens the gland permanently.
- Management ladder: hydration, massage, sialogogues and warm compresses for small stones; antibiotics only for infected obstruction; transoral duct slitting with stone removal or basket retrieval under sialoendoscopy for ductal stones; sialadenectomy for hilar, gland-destroyed or irretrievably recurrent disease; extracorporeal shock wave lithotripsy has a limited role in selected centres.
A meal-time swelling, step by step
A 46-year-old man describes two months of left submandibular swelling and aching that arrives with lunch and drains by evening, with a sour taste at the papilla. Step one, examine at rest and on lemon-juice challenge: the gland enlarges and tightens within a minute of a sialogogue, proving obstruction dynamically. Step two, bimanual palpation — one finger under the tongue along Wharton's duct, the other under the jaw — identifies a stony hard, tender nodule in the anterior floor of the mouth. Step three, image cheaply first: a lower occlusal film shows a radiodense stone of about 6 millimetres in the distal duct. Step four, treat by position: a distal stone of this size is delivered by transoral papillotomy — a stay suture holds it, the duct is incised over it, and the opening is marsupialised. Step five, postoperative care: hydration, sialogogues and massage to flush the system, plus a short course of antibiotics if the gland was inflamed. Step six, explain the contralateral and recurrent risk and review; a stone in the hilar region, or a gland already shrunken and hard from repeated sialadenitis, moves the answer from duct surgery to submandibular gland excision.
Where examiners probe
The favourite question is the anatomical why — candidates who list the four factors (uphill course, tortuosity, mucinous alkaline calcium-rich saliva, and the mylohyoid kink) secure the marks in one breath. The second probe is imaging strategy: a negative film does not exclude a radiolucent or parotid stone, and ultrasound — cheap and widely available in Indian setups — and sialography carry the diagnosis forward. Third, the papillary discharge question: pus at Wharton's papilla on pressure means supervening suppurative sialadenitis needing antibiotics, not just stone retrieval. Fourth, the classical viva trap of the hard, fixed floor-of-mouth nodule in an older adult — a duct carcinoma or a stone can both present with obstruction, and persistence after stone clearance, or tongue anaesthesia, deserves imaging and biopsy rather than reassurance.
Frequently asked questions
Which gland and duct are most commonly affected and why?
The submandibular gland and Wharton's duct, because the duct is long, tortuous and runs uphill against gravity while carrying mucinous, alkaline, calcium-rich saliva.
How does sialolithiasis present classically?
Painful swelling of the affected gland during meals that regresses an hour or two afterwards, often with a history of recurrent sialadenitis and a palpable hard duct nodule.
Which radiographs best demonstrate submandibular stones?
A lower occlusal radiograph and an OPG show most submandibular calculi, which are predominantly radiopaque; ultrasound or sialography is needed for radiolucent and parotid stones.
When is gland excision indicated?
When the stone is hilar or intraglandular and not retrievable, or when repeated obstruction has caused chronic sialadenitis with a functionless, hardened gland.
What complication demands urgent treatment?
Acute suppurative sialadenitis with fever and purulent papillary discharge, managed with antibiotics and relief of the obstruction.