You have three pairs of major salivary glands in your mouth. Salivary duct stones occur most often in the ducts connected to your submandibular glands. These salivary glands are located on both sides of your jaw in the back of your mouth.
Stones can also form in the ducts connected to the parotid glands, which are located on each side of your face in front of your ears. The stones in the submandibular glands are usually bigger than the ones that form in the parotid glands.
You can have one or more stones in your duct. About 25 percent of people with this condition have more than one stone, according to the Merck Manual Home Health Handbook. (Merck).
A salivary gland stone — also called salivary duct stone — is a calcified structure that may form inside a salivary gland or duct. It can block the flow of saliva into the mouth. The majority of stones affect the submandibular glands located at the floor of the mouth.
What Causes Salivary Duct Stones?
Certain substances in your saliva, such as calcium phosphate and calcium carbonate, can crystalize and form stones that range in size from a few millimeters to more than two centimeters. When these stones block your salivary ducts, saliva builds up in your salivary glands, which makes them swell.
The reason why the stones form in the first place isn’t known. A few factors have been associated with a higher risk of having these stones. These include:
taking medications, such as blood pressure drugs and antihistamines, which reduce the amount of saliva your glands produce
being dehydrated, as this makes your saliva more concentrated
not eating enough food, which causes a decrease in saliva production