Periodontal Bone Grafts

Bone grafting is a critical procedure in periodontal surgery, aimed at restoring lost bone and supporting the regeneration of periodontal tissues.

1. Bone Blend

 Bone blend is a mixture of cortical or cancellous bone that is procured using a trephine or rongeurs, placed in an amalgam capsule, and triturated to achieve a slushy osseous mass. This technique allows for the creation of smaller particle sizes, which enhances resorption and replacement with host bone.

Particle Size: The ideal particle size for bone blend is approximately 210 x 105 micrometers.

Rationale: Smaller particle sizes improve the chances of resorption and integration with the host bone, making the graft more effective.

2. Types of Periodontal Bone Grafts

A. Autogenous Grafts

Autogenous grafts are harvested from the patient’s own body, providing the best compatibility and healing potential.

1. Cortical Bone Chips

   • History: First used by Nabers and O'Leary in 1965.
   • Characteristics: Composed of shavings of cortical bone removed during osteoplasty and ostectomy from intraoral sites.
   • Challenges: Larger particle sizes can complicate placement and handling, and there is a potential for sequestration. This method has largely been replaced by autogenous osseous coagulum and bone blend.

2. Osseous Coagulum and Bone Blend

   • Technique: Intraoral bone is obtained using high- or low-speed round burs and mixed with blood to form an osseous coagulum (Robinson, 1969).
   • Advantages: Overcomes disadvantages of cortical bone chips, such as inability to aspirate during collection and variability in quality and quantity of collected bone.
   • Applications: Used in various periodontal procedures to enhance healing and regeneration.

3. Intraoral Cancellous Bone and Marrow

   • Sources: Healing bony wounds, extraction sockets, edentulous ridges, mandibular retromolar areas, and maxillary tuberosity.
   • Applications: Provides a rich source of osteogenic cells and growth factors for bone regeneration.

4. Extraoral Cancellous Bone and Marrow

   • Sources: Obtained from the anterior or posterior iliac crest.
   • Advantages: Generally offers the greatest potential for new bone growth due to the abundance of cancellous bone and marrow.

B. Bone Allografts

Bone allografts are harvested from donors and can be classified into three main types:

1. Undermineralized Freeze-Dried Bone Allograft (FDBA)

   • Introduction: Introduced in 1976 by Mellonig et al.
   • Process: Freeze drying removes approximately 95% of the water from bone, preserving morphology, solubility, and chemical integrity while reducing antigenicity.
   • Efficacy: FDBA combined with autogenous bone is more effective than FDBA alone, particularly in treating furcation involvements.

2. Demineralized (Decalcified) FDBA

   • Mechanism: Demineralization enhances osteogenic potential by exposing bone morphogenetic proteins (BMPs) in the bone matrix.
   • Osteoinduction vs. Osteoconduction: Demineralized grafts induce new bone formation (osteoinduction), while undermineralized allografts facilitate bone growth by providing a scaffold (osteoconduction).

3. Frozen Iliac Cancellous Bone and Marrow

   • Usage: Used sparingly due to variability in outcomes and potential complications.

Comparison of Allografts and Alloplasts

• Clinical Outcomes: Both FDBA and DFDBA have been compared to porous particulate hydroxyapatite, showing little difference in post-treatment clinical parameters.
• Histological Healing: Grafts of DFDBA typically heal with regeneration of the periodontium, while synthetic bone grafts (alloplasts) heal by repair, which may not restore the original periodontal architecture.

Localized Aggressive Periodontitis and Necrotizing Ulcerative Gingivitis

Localized Aggressive Periodontitis (LAP)

Localized aggressive periodontitis, previously known as localized juvenile periodontitis, is characterized by specific microbial profiles and clinical features.

• Microbiota Composition:
  • The microbiota associated with LAP is predominantly composed of:
    • Gram-Negative, Capnophilic, and Anaerobic Rods.
  • Key Organisms:
    • Actinobacillus actinomycetemcomitans: The main organism involved in LAP.
    • Other significant organisms include:
      • Porphyromonas gingivalis
      • Eikenella corrodens
      • Campylobacter rectus
      • Bacteroides capillus
      • Spirochetes (various species).
  • Viral Associations:
    • Herpes viruses, including Epstein-Barr Virus-1 (EBV-1) and Human Cytomegalovirus (HCMV), have also been associated with LAP.

Necrotizing Ulcerative Gingivitis (NUG)

• Microbial Profile:
  • NUG is characterized by high levels of:
    • Prevotella intermedia
    • Spirochetes (various species).
• Clinical Features:
  • NUG presents with necrosis of the gingival tissue, pain, and ulceration, often accompanied by systemic symptoms.

Microbial Shifts in Periodontal Disease

When comparing the microbiota across different states of periodontal health, a distinct microbial shift can be identified as the disease progresses from health to gingivitis to periodontitis:

1. From Gram-Positive to Gram-Negative:

   • Healthy gingival sites are predominantly colonized by gram-positive bacteria, while diseased sites show an increase in gram-negative bacteria.

2. From Cocci to Rods (and Later to Spirochetes):

   • In health, cocci (spherical bacteria) are prevalent. As the disease progresses, there is a shift towards rod-shaped bacteria, and in advanced stages, spirochetes become more prominent.

3. From Non-Motile to Motile Organisms:

   • Healthy sites are often dominated by non-motile bacteria, while motile organisms increase in number as periodontal disease develops.

4. From Facultative Anaerobes to Obligate Anaerobes:

   • In health, facultative anaerobes (which can survive with or without oxygen) are common. In contrast, obligate anaerobes (which thrive in the absence of oxygen) become more prevalent in periodontal disease.

5. From Fermenting to Proteolytic Species:

   • The microbial community shifts from fermentative bacteria, which primarily metabolize carbohydrates, to proteolytic species that break down proteins, contributing to tissue destruction and inflammation.

Sharpening Stones

• Natural: India, Arkansas
• Artificial: Ruby, Carborundum, Ceramic

Surgical Equipment

• Dental loupes: 1.5 – 6× magnification
• Coe – pak working time: 15 – 20 minutes

Preventive Measures

• Calculus control toothpastes: Contain pyrophosphates
• Antibiotic prophylaxis: Amoxicillin 2.0g, 30 – 60 min before procedure

Abrasion Rates

• Dentin: 25× faster than enamel
• Cementum: 35× faster than enamel

• Chlorhexidine:
  • Minimum: 0.12%; Optimum: 0.2%.
  • Chip degrades in 7 – 10 days.
• Floss & Brushes:
  • Preferred floss: Unwaxed thin.
  • Floss length: 12 – 18 inches.
  • Toothbrush: 2 – 4 rows, 5 – 12 tufts per row.
  • Soft bristle diameter: 0.2 mm.
• Powered Brushes: Invented in 1939; use oscillating/rotating motion.
• Fones Technique: Circular brushing method.
• Antiplaque Agents:
  • Bisbiguanides: 2nd generation.
  • Pyrophosphate: Inhibits calculus formation.

Systemic Antibiotics

• Most photosensitizing: Doxycycline
• Only one causing tooth discoloration: Minocycline

Local Drug Delivery

• Atridox: Doxycycline
• Arestin: Minocycline
• Elyzol: Metronidazole
• Periochip: Chlorhexidine
• Actisite: Tetracycline

Host Modulation

• SDD (Sub – antimicrobial Dose Doxycycline): Only FDA – approved host modulating agent

Contraindications and Limitations

Gingivectomy

• Major Contraindication: When pocket bottom is apical to mucogingival junction
• Risk: Inadequate attached gingiva post-surgery

Curettage Protocol

• Prerequisite: Should always be preceded by scaling and root planing
• Rationale: Reduce bacterial load before surgical intervention

GTR (Guided Tissue Regeneration)

Membrane Placement Technique

• Apical Extension: 3-4mm apical to defect margin
• Lateral Extension: 2-3mm laterally beyond defect
• Objective: Exclude epithelial and connective tissue cells

Implant Considerations

Placement Guidelines

• Distance from Mental Foramen: ≥5mm to avoid nerve damage
• Primary Stability: Critical for osseointegration

Micro-movement Tolerance

• Critical Threshold: >150μm causes fibrous tissue formation instead of osseointegration
• Clinical Implication: Importance of proper implant stability