Easy Dentistry Lecture Notes: Oral Mucous Membrane (OMM)

Introduction

• Topic: Oral Mucous Membrane (OMM)
• Importance: Significant for exams
• Structure of the lecture:
  • Basics of OMM
  • Non-keratinized epithelium
  • Keratinized epithelium
  • Gingival sulcus and dento-gingival junction

Basics of Oral Mucous Membrane

• Types of Oral Mucous Membrane:

  1. Masticatory Mucosa
     • Comprises 60% of OMM
     • Includes hard palate and gingiva
  2. Lining Mucosa
     • Comprises 25% of OMM
     • Includes lip, cheek, vestibule, floor of mouth, alveolar mucosa, soft palate
  3. Specialized Mucosa
     • Comprises 15% of OMM
     • Includes dorsum of tongue and taste buds

• Structures in OMM:

  • Dento-gingival junction
  • Vermilion border of lip

Classification of OMM

• Keratinized Mucosa:
  • Includes masticatory mucosa and vermilion border
• Non-Keratinized Mucosa:
  • Includes lining mucosa and specialized mucosa

Functions of OMM

1. Defense
   • Prevents entry of microorganisms and toxins
2. Lubrication
   • Saliva keeps mucous membrane moist for speech, mastication, swallowing, and taste perception
3. Sensory
   • Sensitive to touch, pressure, pain, and temperature
4. Protection
   • Protects deeper tissues from mechanical trauma

Structure of OMM

• Layers of OMM:
  1. Epithelium
  2. Lamina Propria
  3. Submucosa
  4. Underlying Bone/Muscle

Epithelium

• Types:
  • Keratinized (orthokeratinized or parakeratinized)
  • Non-keratinized

Lamina Propria

• Contains salivary glands
• Divided into:
  • Papillary part (just below the epithelium)
  • Reticular part

Submucosa

• Connective tissue layer, varying thickness
• Contains glands, blood vessels, collagen fibers, adipose tissue, and nerves

Comparison of Mucosa Types

• Oral Mucosa:
  • 4 layers: epithelium, connective tissue, submucosa, underlying bone/muscle
• Skin:
  • 3 layers: epidermis (orthokeratinized), dermis, underlying bone/muscle
• Gut Mucosa:
  • 5 layers: epithelium, lamina propria, muscularis mucosa, submucosa, underlying bone/muscle

Interface Between Epithelium and Lamina Propria

• Corrugated interface (serpentine appearance)
• Epithelium forms ridges; connective tissue extensions are papillae
• Basement membrane present between epithelium and lamina propria

Basement Membrane

• Appears 1 to 4 micrometers thick
• Cell-free zone, rich in mucopolysaccharides
• Stains positively with PAS (Periodic Acid-Schiff)
• Composition:
  • Lamina Lucida:
    • Adjacent to epithelium, glycoprotein layer, contains type IV collagen
  • Lamina Densa:
    • Below lamina lucida, contains anchoring fibrils (type VII collagen)
    • Type I and II collagen fibers present

Connective Tissue

• Lamina Propria:
  • Made of papillary and reticular parts
  • Tight interlocking arrangement with epithelium for material exchange
• Ground Substance Contains:
  • Collagen (types I and III), glycoproteins, proteoglycans, and cells (fibroblasts, mast cells, macrophages)

Quiz Questions

1. What percent of the oral mucous membrane does the masticatory mucosa cover?
2. Which type of collagen do anchoring fibrils contain?
3. Which layer is absent in the oral epithelium but present in the intestinal epithelium?

Conclusion

• Importance of understanding OMM for future lectures
• Reminder to subscribe to the channel for updates
• Happy studying!