Gingival Anatomy

• Attached Gingiva Width: Greatest in maxillary incisors (3.5 – 4.5mm) and mandibular incisors (3.3 – 3.9mm)
• Least Width: Maxillary 1st premolars (1.9mm) and mandibular premolars (1.8mm)
• Biological Width: Connective tissue attachment (1.07mm) + Epithelial attachment (0.97mm) = ~2mm
• Oral Epithelium: 0.2 – 0.3mm thick, can be keratinized/parakeratinized

Junctional Epithelium (JE)

• Attached to enamel by hemidesmosomes
• Keratinocytes attached by desmosomes
• Internal basal lamina → tooth surface
• External basal lamina → gingival connective tissue

Cementum

• Maximum thickness: Apical third & furcation (150 – 200μm)
• Coronal half: 16 – 60μm
• Acellular cementum: First formed, covers cervical third
• Cellular cementum: Forms when tooth reaches occlusal plane

PERIODONTAL LIGAMENT (PDL) FIBERS

Principal Fibers (Type I Collagen)

1. Oblique fibers: Largest group, bear vertical forces
2. Alveolar crest fibers: Prevent tooth extrusion
3. Transseptal fibers: Only fibers reconstructed after bone destruction (considered gingival fibers)

Key Point

• Reticular fibers: Type III collagen

• Junctional Epithelium: Attached to enamel via hemidesmosomes; to connective tissue via external basal lamina.
• Corneocyte Formation: Keratinohyalin granules disappear, forming filaggrin.
• Langerhans Cells: Suprabasal level; antigen-presenting with Birbeck granules.
• Keratinization: Oral epithelium is 0.2 – 0.3 mm thick; may be keratinized or parakeratinized.

Connective Tissue of the Gingiva and Related Cellular Components

The connective tissue of the gingiva, known as the lamina propria, plays a crucial role in supporting the gingival epithelium and maintaining periodontal health. This lecture will cover the structure of the lamina propria, the types of connective tissue fibers present, the role of Langerhans cells, and the changes observed in the periodontal ligament (PDL) with aging.

Structure of the Lamina Propria

1. Layers of the Lamina Propria:

   • The lamina propria consists of two distinct layers:
     1. Papillary Layer:
        • The upper layer that interdigitates with the epithelium, containing finger-like projections that increase the surface area for exchange of nutrients and waste.
     2. Reticular Layer:
        • The deeper layer that provides structural support and contains larger blood vessels and nerves.

2. Types of Connective Tissue Fibers:

   • The lamina propria contains three main types of connective tissue fibers:

     1. Collagen Fibers:
        • Type I Collagen: Forms the bulk of the lamina propria and provides tensile strength to the gingival fibers, essential for maintaining the integrity of the gingiva.
     2. Reticular Fibers:
        • These fibers provide a supportive network within the connective tissue.
     3. Elastic Fibers:
        • Contribute to the elasticity and flexibility of the gingival tissue.

   • Type IV Collagen:

     • Found branching between the Type I collagen bundles, it is continuous with the fibers of the basement membrane and the walls of blood vessels.

Langerhans Cells

1. Description:

   • Langerhans cells are dendritic cells located among keratinocytes at all suprabasal levels of the gingival epithelium.
   • They belong to the mononuclear phagocyte system and play a critical role in immune responses.

2. Function:

   • Act as antigen-presenting cells for lymphocytes, facilitating the immune reaction.
   • Contain specific granules known as Birbeck’s granules and exhibit marked ATP activity.

3. Location:

   • Found in the oral epithelium of normal gingiva and in small amounts in the sulcular epithelium.
   • Absent from the junctional epithelium of normal gingiva.

Changes in the Periodontal Ligament (PDL) with Aging

1. Aging Effects:
   • With aging, several changes have been reported in the periodontal ligament:
     • Decreased Numbers of Fibroblasts: This reduction can lead to impaired healing and regeneration of the PDL.
     • Irregular Structure: The PDL may exhibit a more irregular structure, paralleling changes in the gingival connective tissues.
     • Decreased Organic Matrix Production: This can affect the overall health and function of the PDL.
     • Epithelial Cell Rests: There may be a decrease in the number of epithelial cell rests, which are remnants of the Hertwig's epithelial root sheath.
     • Increased Amounts of Elastic Fibers: This change may contribute to the altered mechanical properties of the PDL.

• Mobility Tests: Perio test, Fremitus test.
• Bone Evaluation: Transgingival probing.
• Halitosis Detection: Gold standard = Organoleptic analysis.
• Indices:
  • PMA Index: Gingival disease.
  • Ramfjord Index Teeth: 16, 21, 24, 36, 41, 44.
  • Merin’s Classification: Patient recall.
  • Surrogate Endpoint: Reduction in probing depth.

Laser Classifications

Hard Tissue Lasers

• Er:YAG and Er:YSGG: Highest water absorption coefficients
• Applications: Calculus removal, root surface modification, bone surgery

Soft Tissue Applications

• CO2 Laser: Excellent for soft tissue procedures
• Diode Lasers: Hemostasis and bacterial reduction

Microsurgery Principles

Wound Approximation

• Technique: Butt joint approximation for optimal healing
• Instrumentation: Instruments weighing ≤15-20g for precision

Pathogens Implicated in Periodontal Diseases

Periodontal diseases are associated with a variety of pathogenic microorganisms. Below is a list of key pathogens implicated in different forms of periodontal disease, along with their associations:

General Pathogens Associated with Periodontal Diseases

• Actinobacillus actinomycetemcomitans:

  • Strongly associated with destructive periodontal disease.

• Porphyromonas gingivalis:

  • A member of the "black pigmented Bacteroides group" and a significant contributor to periodontal disease.

• Bacteroides forsythus:

  • Associated with chronic periodontitis.

• Spirochetes (Treponema denticola):

  • Implicated in various periodontal conditions.

• Prevotella intermedia/nigrescens:

  • Also belongs to the "black pigmented Bacteroides group" and is associated with several forms of periodontal disease.

• Fusobacterium nucleatum:

  • Plays a role in the progression of periodontal disease.

• Campylobacter rectus:

  • These organisms include members of the new genus Wolinella and are associated with periodontal disease.

Principal Bacteria Associated with Specific Periodontal Diseases

1. Adult Periodontitis:

   • Porphyromonas gingivalis
   • Prevotella intermedia
   • Bacteroides forsythus
   • Campylobacter rectus

2. Refractory Periodontitis:

   • Bacteroides forsythus
   • Porphyromonas gingivalis
   • Campylobacter rectus
   • Prevotella intermedia

3. Localized Juvenile Periodontitis (LJP):

   • Actinobacillus actinomycetemcomitans
   • Capnocytophaga

4. Periodontitis in Juvenile Diabetes:

   • Capnocytophaga
   • Actinobacillus actinomycetemcomitans

5. Pregnancy Gingivitis:

   • Prevotella intermedia

6. Acute Necrotizing Ulcerative Gingivitis (ANUG):

   • Prevotella intermedia
   • Intermediate-sized spirochetes