How Is Saliva Important for Oral Immunity?
Human saliva is the circulating fluid present in the oral cavity having multiple functions, such as taste transduction or sensation, chewing food, and a source of several immunoglobulins or antibodies that play a major role in oral immunity. The saliva is secreted by the major salivary glands, the parotid, submandibular and sublingual glands, along with the smaller secretions from the minor salivary glands. These secretions contain several enzymes, proteins, ions, and organic molecules, forming a complex oral atmosphere or microbiome. Additionally, saliva has potency for antimicrobial activity, playing an important role in keeping the oral cavity clean and lubricated every time there is an intake of food. This is done by the action of several enzymes during food intake.
After the meal bolus is taken into the esophagus tract orally, the salivary amylase enzyme, which is present in saliva in the maximum concentrated amounts, is in charge of performing the function of digestion. Similarly, saliva's lingual lipase enzyme breaks down fats, while mucous glycoproteins protect oral soft tissues from bacterial invasions and help the body's immune system by acting against them. The enzymes known as glycoproteins bond firmly to tooth enamel, preventing plaque buildup by causing the establishment of a bacterial-resistant pellicle on the tooth's enamel layer. The primary digestion processes of dietary polysaccharides are likewise carried out in saliva. As a result, any decrease in salivary flow has an impact on the salivary glands, both directly and indirectly.
What Are the Types of Developmental Disturbances Affecting Salivary Glands?
Disruptions in development can arise due to either genetic or environmental factors during embryonic development. These disruptions may present themselves at birth or later in life, depending on individual circumstances. When the salivary glands are affected during this developmental process, it can result in altered saliva production. This not only significantly impacts oral immunity but also leads to pronounced oral discomfort and functional problems for those affected.
- Aplasia or Agenesis of One or More Salivary Glands: This is when one or more salivary glands may be absent, unilaterally or bilaterally, in the orofacial cavity resulting in xerostomia or dry mouth and its severe sequelae. Aplasia may occur from various developmental defects such as hemifacial microsomia, LADD syndrome, Treacher Collins syndrome, or mandibulofacial dysostosis. Clinically, these patients with one or more salivary glands absent will have increased dental cavitation or caries in their teeth, oral infections frequently, increased bacterial load (due to lack of or less saliva), taste aberrations or altered taste sensations, or even burning mouth.
- Xerostomia or Dry Mouth: Xerostomia, commonly known as dry mouth, is not a standalone condition but rather a clinical manifestation of various syndromes, developmental abnormalities, or systemic diseases. Examples of such diseases include diabetes mellitus, Parkinson's disease, cystic fibrosis, anemia, sarcoidosis, and deficiencies in vitamins such as vitamin A, riboflavin, or niacin. In addition, physical trauma to the salivary glands, as well as surgical procedures that affect them, can result in dry mouth or xerostomia. Another frequently encountered cause is glandular atrophy following radiotherapy. Sjogren's syndrome, predominantly affecting women above the age of 40, is characterized by symptoms of dry mouth, dry eyes, and rheumatoid arthritis, making it a significant contributor to xerostomia. Proper diagnosis of the underlying cause of dry mouth is essential for dentists to develop an effective treatment plan and establish a favorable long-term prognosis.
- Temporary Conditions Affecting Salivary Glands: In specific cases, infections affecting the salivary glands or conditions indirectly impacting the glands, such as mumps, iodine hypersensitivity, post-operative parotitis, certain medications like anticholinergic or sympathomimetic agents, and temporary blockage of salivary gland ducts, can potentially result in decreased salivary production or inflammation of the salivary glands. Furthermore, individuals experiencing psychological stress, anxiety, or depression may also experience a temporary reduction in salivary flow.
- Palatal Gland Hyperplasia: Systemic disorders, certain syndromes, and medical conditions can affect the minor salivary glands responsible for saliva secretion in the oral cavity. In these cases, an abnormal form of hyperplasia or hypertrophy (enlargement) of the salivary glands can manifest as swelling. This swelling can lead to blockage or reduced flow of saliva in the mouth.
- Atresia: This is a congenital condition or syndrome characterized by the absence of one or more major salivary gland ducts. While it is less common than aplasia (absent) of the salivary gland itself, the absence of salivary ducts can result in insufficient saliva production, leading to the potential development of retention cysts or severe xerostomia (dry mouth).
- Stafne Bone Cyst: This condition is known as salivary gland ectopia, which refers to the developmental anomaly in which remnants of glandular tissue are present within the mandible or lower jaw. It is alternatively referred to as latent bone cyst, static bone cyst, or lingual mandibular bone cavity defect.
- Accessory Gland Aberrancy: These are problems with the accessory salivary glands' development that are difficult to locate in the mouth. For instance, they might be discovered anywhere on the tongue, palate, buccal mucosa, retromolar pad, lips, or floor of the mouth. Such accessory gland anomalies are clinically significant because they may result in retention cysts, tumors, or malignant neoplasms of the salivary glands in the affected regions.
How Are Developmental Disturbances of Salivary Glands Managed?
In order to manage the abnormalities of the salivary glands, the oral surgeon may choose an interdisciplinary approach because it is important to identify the underlying reason or the systemic origin on which the treatment plan will be based. A confirmatory diagnosis can be obtained by an oral pathologist after performing an excision biopsy of the diseased salivary gland, which is a frequent first stop in microscopic analysis and histopathologic evaluation of the affected tissue. In order to treat these symptoms, the dentist may also recommend surgery, salivary replacements, mouthwashes, fluoride therapy, and rigorous dental hygiene guidelines.
Conclusion
Numerous developmental disorders affect the salivary glands, and decreased saliva is a major functional problem in those who have this condition, as oral immunity is severely compromised. A timely diagnosis by the oral surgeon can be important for the affected people's long-term functional prognosis.
