Case #3 Diagnoses: Salivary Stone or Sialolith

Radiographic Images:

Figure 6. Occlusal Image of a Sialolith.
Figure 7. Periapical Images of a Sialolith.

Demographics: Commonly diagnosed in middle-age adults, with 4% of cases occurring in individuals younger than 20 years of age. There is a slight male predilection than females.3

Salivary stones or sialoliths are stony calculi that commonly cause salivary gland obstruction and are the most common nonneoplastic disease of the major salivary glands. These mineralised stones typically develop in the ducts of the submandibular or parotid glands. Approximately 80-92% form in the Wharton duct of the submandibular gland (Figures 6 and 7), 6-20% form in the Stenson duct of the Parotid gland, and 1-2% occur in the sublingual glands. The rationale for a higher prevalence of calcifications in the submandibular glands may be due to the saliva having more viscous, mucoid secretions than parotid glands and the anatomical configuration where the Wharton’s duct has two bends. One is located at the posterior border of the mylohyoid muscle and the other is around the opening of the duct (punctum) where the duct makes a sharp bend before emptying saliva into the oral cavity. The diameter of the salivary gland ducts on average is 2-4 mm. However, it is narrower at the salivary gland duct openings.2-5,9

Although considered idiopathic, salivary stones may occur due to the secretion of calcium-rich saliva in conjunction with a partial obstruction of the salivary gland duct due to bacteria, foreign bodies, collection of viscous mucus, or ductal epithelial cells. These blockages may cause an acute or chronic inflammation at the duct site. Other causes of salivary stones may include dehydration and medications. Salivary stones may also occur in minor salivary glands. However, they are rare. If a minor salivary gland duct is blocked, the dental professional can identify the stones in the upper lip and buccal mucosa areas appearing as small, firm nodules. It is important to note that salivary stones may occur secondary to neoplasms, such as acinic cell or mucoepidermoid carcinomas.3-4

Clinical Notes: Hyposalivation or xerostomia are one of the first symptoms of salivary duct blockage. Pain, oedema, and inflammation may occur. Typically, the oedema is sudden and associated with the patient eating a meal. Patients with minor salivary gland stones are typically asymptomatic. Radiographically salivary stones range from tiny particles to stones that are several centimeters in size. They typically appear radiopaque. However, some stones may appear radiolucent.4

Differential Diagnoses: Sjögren syndrome, obstructive sialadentitis, salivary gland tumours, or epidemic parotitis (mumps). If mumps are suspected, look for other symptoms such as fever, malaise, and acute persistent pain and oedema of the parotid gland along with inflammation of the papilla of the Stenson duct. Do not dilate the salivary duct (balloon dilation) if the patient has a suspected case of mumps. Salivary stones are primarily composed of calcium phosphate and hydroxyapatite. However, uric acid stones may form in patients with gout. As many as 10% of individuals diagnosed with salivary stones also exhibit stone formation in the urinary tract and bile duct system.4

Treatment: If left untreated, salivary stones can result in chronic sialadentitis (infection of the salivary gland) and glandular atrophy (decrease in the saliva gland size). Conservative treatment includes oral analgesics and antibiotics for secondary infections or the potential for secondary infections after a protracted or traumatic surgery. Surgical management includes salivary lithotripsy (ultrasonic wave therapy) or sialendoscopy (surgical removal). Salivary stones smaller than 7 mm in diameter, relatively mobile, and proximal anatomical positioning are good candidates for removal with forceps or wire stone removal baskets utilising endoscopic guidance. With salivary stones larger than 7 mm, lithotripsy is indicated. The ultrasonic pulses cause the stones to be fragmented and are either removed if they are still large or excreted by saliva. The stones will appear white, yellowish, or tan in colour and smooth or rough in appearance. When removed, the calcifications may crumble (friable).3

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