Sialolithiasis: Symptoms, Types, Causes and Treatment

Sialolithiasis is a surprisingly common yet often overlooked disorder that affects the salivary glands. Manifesting as the formation of hard, stone-like deposits (sialoliths) within the glands or their ducts, this condition can lead to significant discomfort and complications if left untreated. Understanding the symptoms, types, causes, and available treatments for sialolithiasis is essential for early recognition and optimal care. This article explores the latest research and clinical insights to provide a comprehensive overview of this multifaceted condition.

Symptoms of Sialolithiasis

Sialolithiasis can present in various ways, ranging from mild discomfort to severe, recurrent pain. The symptoms often fluctuate and are closely tied to meals or salivary stimulation, making them both distinctive and sometimes misleading. Recognizing these signs is crucial for prompt diagnosis and effective management.

Symptom	Description	Frequency/Pattern	Source(s)
Swelling	Gland enlarges, especially at meals	Recurrent, often meal-related	1, 2, 4
Pain	Sharp or dull ache in affected area	Typically periprandial (mealtime)	1, 2, 4
Dry mouth	Reduced saliva flow (xerostomia)	Persistent or intermittent	2, 3, 4
Pus/discharge	Purulent fluid from gland duct	With infection or severe blockage	4, 11

Table 1: Key Symptoms

Swelling and Pain

The hallmark symptom of sialolithiasis is swelling of the affected salivary gland, typically in the submandibular or parotid region. This swelling often becomes pronounced during or shortly after eating, as saliva production increases and attempts to flow past an obstruction. Patients frequently describe a sharp or throbbing pain that accompanies the swelling, which may subside between meals or after the obstruction is temporarily relieved 1, 2, 4.

Xerostomia and Salivary Dysfunction

A decrease in saliva flow, known as xerostomia, is another common symptom. This reduction in salivary output can lead to a persistently dry mouth, increased risk of dental caries, and difficulty swallowing or speaking 2, 3.

Infection and Discharge

If a stone causes prolonged blockage, secondary infection (sialadenitis) may develop. This can result in the discharge of pus from the duct opening, fever, and general malaise. In severe cases, the gland may become hard, fibrotic, and lose its normal function 4, 11.

Asymptomatic Cases

Interestingly, some cases of sialolithiasis may be entirely asymptomatic, especially if the stones are small or not causing significant obstruction. These are often discovered incidentally during imaging for unrelated concerns 3.

Types of Sialolithiasis

Understanding the various types of sialolithiasis is vital for accurate diagnosis and treatment planning. Sialoliths can be classified based on their composition, location, and growth pattern, each with unique clinical implications.

Type	Description	Prevalence/Location	Source(s)
Calcified	Predominantly inorganic, hydroxyapatite	Most common, submandibular	5, 7, 1
Organic	Rich in organic/lipid components	Less common, variable sites	5, 7
Mixed	Both calcified and organic layers	Formed as CAL, grow as LIP	5
Gland-based	Based on affected gland (SMG, PG, SLG)	SMG: 80–90%, PG: 6–10%, SLG: rare	1, 3, 6

Table 2: Sialolith Types and Distribution

Composition-Based Types

Recent ultrastructural research has identified three principal types of sialoliths:

• Calcified (CAL): These stones have a core rich in inorganic materials, primarily hydroxyapatite (a calcium phosphate mineral). They commonly occur in the submandibular gland and are the most frequently encountered form 5, 7, 1.
• Organic/Lipid (LIP): These stones are dominated by organic or lipid-rich components. They are less common and may have a different pathway of formation, with a softer, more pliable structure 5, 7.
• Mixed (MIX): These have both calcified and organic layers. Their core typically resembles that of CAL stones but, as they grow, they incorporate more organic material, taking on characteristics of LIP stones 5.

Location-Based Types

Sialolithiasis is also classified by the gland or duct involved:

• Submandibular Gland (SMG): The majority of cases (80–90%) occur here due to the gland’s anatomical and biochemical environment, which favors stone formation 1, 3.
• Parotid Gland (PG): A smaller percentage (6–10%) 1, 3.
• Sublingual and Minor Glands (SLG): Rarely affected (2–3%) 1, 6.

Stone Characteristics and Growth Patterns

Sialoliths can be solitary or, less commonly, multiple. Their shapes range from round and elongated to irregular. While most are a few millimeters in diameter, some can grow to several centimeters, especially if not detected early 1, 3, 4, 16.

Causes of Sialolithiasis

The exact origins of sialolithiasis remain a subject of ongoing research. Multiple interrelated factors—both local and systemic—contribute to the development of salivary stones.

Cause	Mechanism/Description	Evidence/Notes	Source(s)
Mineral Precipitation	Supersaturation of saliva with minerals	Calcium phosphate, hydroxyapatite	1, 3, 7
Organic Matrix	Formation around organic nidus/biofilm	Initiation of stone growth	5, 8, 10
Inflammation	Chronic sialadenitis, immune response	NETs and biofilm involvement	6, 8, 10
Ductal Abnormalities	Stenosis, anatomical variations	Impaired saliva drainage	4, 16
Smoking	Increased risk in smokers	Statistically significant	9

Table 3: Main Causes of Sialolithiasis

Mineral and Organic Nidus

Most sialoliths begin with the deposition of mineral salts—especially calcium phosphate (hydroxyapatite)—around a central nidus. This nidus is often composed of organic material, such as mucins, cell debris, or bacterial biofilms 1, 3, 5, 7. Research indicates that a deficiency in natural crystallization inhibitors, like phytate (myo-inositol hexaphosphate), may facilitate stone formation 7.

Role of Biofilms and Inflammation

Recent studies suggest that microbial biofilms within the salivary ducts play a central role in the initiation of sialoliths. These biofilms can trigger a local immune response, with neutrophil extracellular traps (NETs) forming a sticky, DNA-rich scaffold that further promotes mineral aggregation and stone growth 8, 10.

Ductal and Glandular Factors

Anatomical features of the submandibular gland—such as a long, tortuous duct and alkaline, mineral-rich saliva—make it especially prone to stone formation. Ductal stenosis or narrowing due to previous inflammation may also contribute by impeding normal saliva flow, encouraging stasis and precipitation 4, 16.

Lifestyle and Systemic Risk Factors

Smoking has been shown to significantly increase the risk of sialolithiasis, likely through its effects on oral mucosa and salivary composition. However, studies have not found a significant association with alcohol consumption or obesity 9.

Other Predisposing Factors

• Poor oral hygiene
• Dehydration (leading to thicker saliva)
• Medications that decrease salivary flow
• History of nephrolithiasis (kidney stones), as a subset of patients show both conditions concurrently 1

Treatment of Sialolithiasis

The approach to managing sialolithiasis has evolved rapidly, with modern therapies prioritizing gland preservation and minimally invasive methods. Treatment is tailored to the stone’s size, location, and the severity of symptoms.

Treatment	Method/Technique	Indication/Outcome	Source(s)
Conservative	Hydration, massage, sialogogues	Small stones, early cases	2, 14
Sialendoscopy	Endoscopic stone removal/fragmentation	Most stones, gland-sparing	13, 14, 12
Lithotripsy	Shockwave or laser to break stones	Small–medium stones	12, 13, 14
Surgery	Transoral or external removal, gland excision	Large/deep stones, recurrences	4, 16, 13
Adjunctive	Antibiotics, steroids, mucolytics	Infection, inflammation	15

Table 4: Main Treatment Options

Conservative Management

For small, mobile stones or early cases, conservative measures like increased hydration, gland massage, application of warm compresses, and use of sialogogues (agents that stimulate saliva flow) may lead to spontaneous stone passage 2, 14. Mild pain and swelling often resolve with these strategies.

Minimally Invasive Techniques

Sialendoscopy

Sialendoscopy—a technique involving the insertion of a tiny endoscope into the duct—allows direct visualization and removal or fragmentation of stones. This gland-preserving approach is now considered the gold standard for most cases, with high success rates and minimal complications 13, 14.

Lithotripsy

Extracorporeal shockwave lithotripsy (ESWL) and intracorporeal laser lithotripsy (such as holmium laser) can fragment stones into smaller pieces that are then removed or pass naturally. These methods are particularly effective for small to medium stones in the parotid and submandibular glands 12, 13, 14.

Surgical Approaches

For large, deep, or recurrent stones not amenable to endoscopic removal, minor surgical procedures may be necessary:

• Transoral stone removal is commonly used for accessible submandibular stones 13, 16.
• Gland excision (removal of the affected gland) is reserved as a last resort for cases where other treatments fail or the gland is irreversibly damaged 13, 14, 16.

Adjunctive and Supportive Therapies

In cases complicated by infection or persistent inflammation, antibiotics, steroids, and mucolytic agents may be administered—sometimes directly into the duct via sialoendoscopy—to reduce swelling and resolve symptoms 15.

Recurrence and Long-Term Management

Although recurrence rates are generally low, stones can regrow, particularly if the underlying risk factors are not addressed. Revision surgery or repeated endoscopic procedures may be required in some cases 16.

Conclusion

Sialolithiasis, while common, is a complex disease influenced by a variety of local and systemic factors. Prompt recognition and modern, gland-preserving treatments offer excellent outcomes for most patients. Here’s a summary of the main points:

• Symptoms: Classic features include recurrent, meal-related swelling and pain, with possible dry mouth and pus discharge.
• Types: Stones are classified by composition (calcified, organic, mixed) and gland involved (submandibular most common).
• Causes: Multifactorial origins include mineral precipitation, biofilm formation, immune responses, anatomical factors, and smoking.
• Treatment: Advances favor minimally invasive, gland-preserving techniques (sialendoscopy, lithotripsy), with surgery reserved for complex cases.

Early diagnosis and a tailored, stepwise treatment approach can minimize complications and restore quality of life for individuals affected by sialolithiasis.