Sialolithiasis or salivary stone or salivary calculi are a condition in which a mass of crystallized minerals are formed in the salivary ducts. Salivary duct stones can develop in all salivary glands, but most commonly in the submandibular glands, which are situated in the back of the mouth and both sides of the jaw. There is a possibility of stone formation in the parotid gland but they are much rarer. Usually more than one stone is formed in the duct.
The size of the stone may range from a few mm to more than 2 cm and appears as round or oval rough or smooth solid masses. The color of the stone is usually yellowish or yellowish white. As the saliva is rich in calcium, stones are typically made up of hydroxyapatite and calcium phosphate
Mechanism of sialolith formation
The definite mechanism of sialolithiasis is still unknown. It is believed that at the beginning a small and soft nidus is formed within the salivary gland and its ducts due to being large, long, and having slow salivary flow.
Nidus is composed of protein acteria, mucin, and desquamated epithelial cells. Once if the nidus forms, it allows crystallization of minerals similar to concentric lamellae due to the precipitation of calcium salts. Later the size of salolithiasis increases with time as layer by layer of calcium salts deposition.
A very small salivary stones is expelled from the duct along with the salivary secretions, but the larger stones are continues to grow until the duct is fully closed.
It is very much important to monitor the functions of submandibular glands and its ducts for any other malfunction in salivary secretions.
Causes of Stone formation
- The cause of sialolithiasis is still unknown, but there are some researchers suggest some factors that contribute to develop sialolith. Sialolithiasis may develop even if you are healthy.
- Dehydration can cause high viscosity and decreasing of water proportion in the saliva, which makes the calcium and phosphates present in the saliva to form a stone. This stone obstructs the salivary duct and its gland.
- Yet there are some other factors that afford to this condition are as follows:
- Salivary stagnation
- Reduced food intake
- Calcium salt precipitation
- Epithelial injury near the salivary duct may create unwanted salivary stone
- Less salivary secretion
- Constant use of medications for anti-psychotic, anti-hypertensives and anti-histamine drugs which really affect the manufacture of saliva of the mouth.
- Frequent use of diuretics and anticholinergics.
- In some diseases like Sjorgen’s syndrome, lupus, and autoimmune disease attacks the salivary glands by the body’s own immune system.
- Radiation therapy of the mouth
- Chronic periodontal disease
People with salivary calculi tend to be asymptomatic however small segments have some symptoms.
- Facial swelling
- Swelling and pain around the jaw and ear
- Painful lump under the tongue
- Swelling of affected glands occurs while eating a food
- Difficult in opening mouth
- Dry mouth
- Bacterial infection occurs when the mouth glands are filled with stagnant saliva
- Fever and chillness may associate with gland infections
- Redness around the infected gland
- Foul taste in the mouth
- Eating food is tedious work
- Ulceration, fistula, and sinus tract in the affected area may develop a chronic form of sialolithiasis
- Lobular fibrosis and necrosis of gland acini can occur which results in loss of salivary secretion in the glands.
- Acute suppurative sialoadenitis and duct narrowing (stricture)
- Untreated sialolith for long term lead to painful infections, scarring, and forms abscess in the salivary gland.
Diagnosis and Test
Differential diagnosis – Your doctor will ask for previous medical history. Some infectious diseases such as mumps, Sjögren’s syndrome, sarcoidosis, or salivary gland tumour (unilateral swelling) might associate with sialolithiasis.
X-ray – The possible way to visualize the salivary stone is x-ray because the stone in the submandibular gland is rich in calcium phosphate as in bone. However, there are also other components in the salivary stone and is less likely to show the stones through X-ray.
Sialography – It is a technically superior to X-ray in identifying sialoliths. Sialography uses X-ray as similar to normal X-rays; however a contrast dye injected into the affected salivary gland before the X-rays passed through. This dye is helpful in examining the anatomy of the salivary calculi.
CT-Scan – Computed tomography is used with a contrast dye injection before undergoing the scanning step. However CT is used in very rare cases having more than one stone in the duct.
Treatment and medications
There are different options of treatment for sialolithiasis, which are dependent upon the size and location of the stones. After the stones are diagnosed, the following home treatments are recommended initially. The goal of the treatment is to increase the salivary secretion and purge out the stones from the duct.
- Hydration – Drinking plenty of water and sucking sugar free lemon drops.
- Warm compresses – Applying heat on the stone
- Gland massage – Massaging the affected area
- Use of antibiotics to stop the spread of infection
Large salivary stones and deep located stones are difficult to force out from the duct by home treatments. These stones are removed by cutting down the entire salivary gland, which is a traditional way of treating the sialolithiasis. You will make enough spit (saliva) from your remaining glands if one is removed. Later advances in the endoscopic techniques helped to treat the salivary stones in a less invasive ways.
Endoscopy of salivary glands is also performed to remove the sialolith. An endoscope with a camera and light, is inserted into the gland or duct and grabber tool is used to remove the stone from the duct. This procedure is performed by a doctor. A local anesthetic is injected into the affected area.
Extracorporeal Shock Wave Lithotripsy (ESWL)
ESWL is an ultrasonic technique referred as ultrasonic lithotripsy, which uses ultrasound waves to break up the stone in the duct. The broken stones are allowed to pass through the same salivary gland. Since the effectiveness of this treatment is yet to be validated and so doctors do not recommend often.
Trans Oral Ductotomy
This is the opening of the Wharton Duct for it to be cannulated and dilated so the stone can be completely removed through trans-oral approach.
Side effects of sialolithiasis treatment
- Scarring of the duct when it is excised off.
- Infections may spread to nearby glands during surgical removal of glands.
- Recurrent of stone may take place.
Since the exact cause of sialolithosis is unknown, there are no appropriate ways to prevent this condition. However, all doctors advise to take enough water daily.