The major salivary glands (paired on each side). 1. Parotid gland, 2. Submandibular gland, 3. Sublingual gland. There are thought to be a series of stages that lead to the formation of a calculus (lithogenesis). Initially, factors such as abnormalities in calcium metabolism, dehydration, reduced salivary flow rate, altered acidity (pH) of saliva caused by oropharyngeal infections, and altered solubility of crystalloids, leading to precipitation of mineral salts, are involved. Other sources state that no systemic abnormality of calcium or phosphate metabolism is responsible. The next stage involves the formation of a nidus which is successively layered with organic and inorganic material, eventually forming a calcified mass. In about 15-20% of cases the sialolith will not be sufficiently calcified to appear radiopaque on a radiograph, and will therefore be difficult to detect. Other sources suggest a retrograde theory of lithogenesis, where food debris, bacteria or foreign bodies from the mouth enter the ducts of a salivary gland and are trapped by abnormalities in the sphincter mechanism of the duct opening (the papilla), which are reported in 90% of cases. Fragments of bacteria from salivary calculi were reported to be Streptococci species which are part of the normal oral microbiota and are present in dental plaque. Stone formation occurs most commonly in the submandibular gland for several reasons. The concentration of calcium in saliva produced by the submandibular gland is twice that of the saliva produced by the parotid gland. The submandibular gland saliva is also relatively alkaline and mucous. The submandibular duct (Wharton's duct) is long, meaning that saliva secretions must travel further before being discharged into the mouth. The duct possesses two bends, the first at the posterior border of the mylohyoid muscle and the second near the duct orifice. The flow of saliva from the submandibular gland is often against gravity due to variations in the location of the duct orifice. The orifice itself is smaller than that of the parotid. These factors all promote slowing and stasis of saliva in the submandibular duct, making the formation of an obstruction with subsequent calcification more likely. Salivary calculi sometimes are associated with other salivary diseases, e.g. sialoliths occur in two thirds of cases of chronic sialadenitis, although obstructive sialadenitis is often a consequence of<unk> . Gout may also cause salivary stones, although in this case they are composed of uric acid crystals rather than the normal composition of salivary stones.
Sialolithiasis
Goa stone
Pulp stone
Hepatolithiasis
Gallstone
Porcelain gallbladder
Common bile duct stone
Biliary pseudolithiasis