Submandibular calculi are common because stasis in the duct is encouraged both by the submandibular glands lying below the opening of the duct on the floor of the mouth, and the large mucous content of the secretions of the submandibular gland. They may be found anywhere along Warthin's duct, including its course within the gland. They vary in size from several millimetres to centimetres in diameter. Those in the distal part tend to have an elongated 'date stone' shape.
They should be differentiated from a stenosis of the duct orifice due to repeated trauma and fibrosis, e.g. following irritation from a sharp tooth, or a bite of the cheek.
- 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
- males and females are equally affected