Submandibular Sialolithiasis

Epidemiology

Submandibular sialoliths usually occur between 30 and 50 years of age and are slightly more common in men. Salivary gland calculi are rare in children and when present usually involve the submandibular gland. Submandibular gland stones constitute between 80 and 90% of all salivary gland stones. The majority of submandibular stones are single (> 70%). Multiple stones are more commonly seen in patients with chronic sialadenitis.

Pathology

Submandibular sialoliths are composed of calcium phosphate in the form hydroxyapatite with small amounts of magnesium, carbonate, and ammonium. The matrix consists of carbohydrates and amino acids.

Several explanations have been proposed for the higher incidence of stones in the submandibular gland compared with the parotid gland. These include thicker and more mucous secretions, a narrow orifice, an uphill course of Wharton’s duct in the standing position, a more alkaline pH that facilitates precipitation of salts, and a higher concentration of hydroxyapatite and phosphatase.