Salivary gland calculi

Sialolithiases are calcified stones which deposit in the salivary glands. They obstruct salivary outflow and predispose to infection.

• sialolithiasis may be associated with swelling, pain, and infection of the affected gland
• the majority of salivary calculi (80% to 95%) occur in the submandibular gland, whereas 5% to 20% are found in the parotid gland
  • sialothiasis rarely affects the sublingual gland and the minor salivary glands are rarely (1% to 2%) (1)
• sialolithiasis can occur at any age - however most cases occur in patients in their third to sixth decade. Sialothiasis rarely occurs in children
• size of the salivary calculi varies from less than 1 mm to a few cm in largest diameter
  • majority of calculi (88%) are less than 10 mm in size, whereas only 7.6% are larger than 15 mm (1)
  • calculi occuring in the parotid gland are usually smaller than those in the submandibular gland (submandibular calculi tend to be large and single; those in the parotid, small and multiple)
  • plain X-rays
    • occlusal and lateral-oblique views demonstrate most calculi (20% of calculi are radiolucent and hence undetectable)
  • sialography allows examination of the architecture of the salivary gland and duct, whereas ultrasonography, computed tomography and magnetic resonance imaging are particularly useful in evaluating masses in the salivary glands (2)
• the calculi are composed of inorganic calcium and sodium phosphate salts mixed with mucous and cellular debris. They are radio-opaque and may be visualised on intraoral radiographs.

The aetiology of salivary calculi is not known, but the submandibular gland is thought to be more vulnerable because of its more viscid secretion and elongated duct.

Reference:

1. Bodner L. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002 Sep;94(3):320-3.
2. Can Assoc Radiol J. 1993 Oct;44(5):342-9