Brief Overview of Salivary Gland Anatomy and Physiology

The majority of saliva comes from three major, paired salivary glands: the parotid, the submandibular, and the sublingual. Contributing to the total salivary production, 600-1000 minor salivary glands line the oral cavity and oropharynx. The largest salivary gland is the Parotid gland followed by the submandibular gland weighing 50% less than the Parotid.21 The sublingual gland is the smallest of the major salivary glands. The minor salivary glands lack a branching network of draining ducts, but instead each salivary unit has its own simple duct.21 Most of the minor salivary glands are located in the buccal, labial, palatal, and lingual regions. In addition, minor salivary glands, sometimes found at the superior pole of the tonsils (Weber’s glands), the tonsillar pillars, at the base of the tongue (von Ebner’s glands), paranasal sinuses, larynx, trachea, and bronchi.21

The salivary glands of the oral cavity are classified as serous, mucous, or mixed according to the nature of their secretory product(s). The parotid gland is a serous salivary gland, also containing fat cells. The submandibular gland is mixed but mostly serous. The sublingual gland is mixed but mostly mucous.21

Functions of saliva:

  1. Moistens oral mucosa. The mucin layer on the oral mucosa, considered the most significant non-immune defense mechanism in the oral cavity.
  2. Moistens dry food and cools hot food.
  3. Provides a medium for dissolved foods to stimulate taste buds.
  4. Buffers oral cavity contents with a high concentration of bicarbonate ions.
  5. Aids in digestion.
  6. Controls bacterial flora of the oral cavity. Saliva is a medium for the transportation of planktonic bacteria within or between hosts. Saliva also provides a conditioning film of salivary proteins on oral surfaces and sets the stage for oral biofilm formation and microbial adherence. Salivary agglutinins can also prevent some bacteria from sticking to oral surfaces.22 Lysozyme, secretory IgA (sIgA), and salivary peroxidase play significant roles in the antibacterial function of saliva. Lysozyme agglutinates bacteria and Iga interferes with the adherence of microorganisms to host tissue. Peroxidase oxidizes the enzymes involved in bacterial glycolysis.21
  7. Mineralization of new teeth and repair of precarious enamel lesions.
  8. Protects the tooth by forming a “protective pellicle.”