Normal Salivary Gland Function
Three paired glands secrete saliva continuously and adequately.
- 0.3–0.4: Total resting flow (mL/min, healthy baseline)
- ~20%: Parotid contribution (serous, enzyme-rich)
- ~65%: Submandibular contribution (mixed seromucous)
- ~8%: Sublingual contribution (mucin-rich, viscous)
Three paired major glands
Parotid, submandibular, and sublingual glands work together.
Healthy adults produce about one liter of saliva daily.
Ducts deliver saliva into the mouth
Stensen's and Wharton's ducts channel secretions orally.
Balanced composition sustains oral health
Enzymes, mucins, and buffers protect teeth and tissue.
Parotid Gland Hypofunction
Reduced parotid output lowers the watery, enzyme-rich fraction.
- ↓ 65%: Parotid flow (serous acinar loss)
- ↓: Amylase output (starch digestion impaired)
- ↓: Bicarbonate buffering (less acid neutralization)
- more acidic: Oral pH swing (reduced buffering capacity)
Serous acini produce watery fluid
Parotid acini secrete thin, enzyme-rich, bicarbonate-heavy saliva.
Parotid saliva supplies most of the bicarbonate buffer.
Amylase and buffering decline together
Less parotid flow means less starch digestion and buffering.
Cheek and molar dryness appears first
Stensen's duct output near the molars drops noticeably.
Submandibular & Sublingual Hypofunction
Reduced mixed seromucous secretion thins the protective mucin coat.
- ↓ 70%: Submandibular flow (largest resting contributor lost)
- ↓: Mucin concentration (less viscoelastic coating)
- ↓: Lubrication adequacy (friction rises on mucosa)
- reduced: Floor-of-mouth wetness (Wharton's duct output falls)
Submandibular glands dominate resting flow
They normally supply most saliva at rest.
Submandibular glands provide about two-thirds of resting saliva.
Mucins provide lubrication and coating
Sublingual mucus protects mucosa from friction and drying.
Speech and swallowing feel effortful
Thinner lubrication makes chewing and talking harder.
Combined Salivary Gland Hypofunction
All three gland pairs underperform, and total flow drops sharply.
- ↓ 80%: Total flow (well below normal baseline)
- high: Xerostomia risk (subjective dry mouth likely)
- slow: Oral clearance rate (food and debris linger)
- acidic drift: Salivary pH (buffering overwhelmed)
Flow falls below the functional threshold
Below roughly 0.1 mL/min, the mouth feels dry.
Below 0.1 mL/min resting flow, xerostomia symptoms typically appear.
Multiple functions fail simultaneously
Lubrication, buffering, and clearance all decline together.
Common causes compound gland damage
Sjögren's syndrome, radiation, and medications drive combined loss.
Functional Consequences of Hypofunction
Impaired saliva raises decay, infection, and discomfort risk.
- elevated: Caries risk (less remineralization and clearance)
- elevated: Oral infection risk (reduced antimicrobial defense)
- reduced: Mucosal comfort (friction, soreness, fissuring)
- depleted: Antimicrobial proteins (lysozyme, lactoferrin, sIgA fall)
Lubrication loss causes mucosal damage
Dry tissue cracks, chafes, and becomes sore.
Chronic hypofunction significantly raises dental caries and candidiasis risk.
Buffering loss accelerates tooth decay
Acid lingers longer without bicarbonate neutralization.
Antimicrobial proteins normally guard the mouth
Lysozyme, lactoferrin, and sIgA control microbial growth.