Classification of Cementum According to Schroeder

Cementum is a specialized calcified tissue that covers the roots of teeth and plays a crucial role in periodontal health. According to Schroeder, cementum can be classified into several distinct types based on its cellular composition and structural characteristics. Understanding these classifications is essential for dental professionals in diagnosing and treating periodontal conditions.

Classification of Cementum

1. Acellular Afibrillar Cementum:

   • Characteristics:
     • Contains neither cells nor collagen fibers.
     • Present in the coronal region of the tooth.
     • Thickness ranges from 1 µm to 15 µm.
   • Function:
     • This type of cementum is thought to play a role in the attachment of the gingiva to the tooth surface.

2. Acellular Extrinsic Fiber Cementum:

   • Characteristics:
     • Lacks cells but contains closely packed bundles of Sharpey’s fibers, which are collagen fibers that anchor the cementum to the periodontal ligament.
     • Typically found in the cervical third of the roots.
     • Thickness ranges from 30 µm to 230 µm.
   • Function:
     • Provides strong attachment of the periodontal ligament to the tooth, contributing to the stability of the tooth in its socket.

3. Cellular Mixed Stratified Cementum:

   • Characteristics:
     • Contains both extrinsic and intrinsic fibers and may contain cells.
     • Found in the apical third of the roots, at the apices, and in furcation areas.
     • Thickness ranges from 100 µm to 1000 µm.
   • Function:
     • This type of cementum is involved in the repair and adaptation of the tooth root, especially in response to functional demands and periodontal disease.

4. Cellular Intrinsic Fiber Cementum:

   • Characteristics:
     • Contains cells but no extrinsic collagen fibers.
     • Primarily fills resorption lacunae, which are areas where cementum has been resorbed.
   • Function:
     • Plays a role in the repair of cementum and may be involved in the response to periodontal disease.

5. Intermediate Cementum:

   • Characteristics:
     • A poorly defined zone located near the cementoenamel junction (CEJ) of certain teeth.
     • Appears to contain cellular remnants of the Hertwig's epithelial root sheath (HERS) embedded in a calcified ground substance.
   • Function:
     • Its exact role is not fully understood, but it may be involved in the transition between enamel and cementum.

Clinical Significance

• Importance of Cementum:

  • Understanding the different types of cementum is crucial for diagnosing periodontal diseases and planning treatment strategies.
  • The presence of various types of cementum can influence the response of periodontal tissues to disease and trauma.

• Cementum in Periodontal Disease:

  • Changes in the thickness and composition of cementum can occur in response to periodontal disease, affecting tooth stability and attachment.

ANUG (Acute Necrotizing Ulcerative Gingivitis)

• Signs: Punched – out crater depressions of interdental papilla
• Symptoms: Metallic foul taste, pasty saliva
• Treatment: 3 visits (2nd visit: 1 – 2 days after 1st; 3rd visit: 5 days after 2nd)

NUG/NUP

• No pocket formation (destroys junctional epithelium)

Primary Herpetic Gingivostomatitis

• Cellular change: Ballooning degeneration → Tzanck cells
• Treatment:
  • Within 3 days: Acyclovir 15 mg/kg × 5 times × 7 days
  • After 3 days: Supportive care with NSAIDs

Leukemic Gingivitis

• Most common in acute monocytic leukemia

Lead Intoxication

• Steel gray linear pigmentation (Burton's line)

Infection Timeline Post-BMT

Phase I: Pre-engraftment (0-30 days)

• Earliest infection: Herpes Simplex Virus (HSV)
• Other pathogens: Bacteria, Candida, Aspergillus
• Risk factors: Neutropenia, mucositis, central lines

Phase II: Early post-engraftment (30-100 days)

• ~7th week (50 days): Interstitial Pneumonitis peak incidence
• Causes: CMV, Pneumocystis jirovecii, idiopathic
• GVHD: Acute graft-versus-host disease peak

Phase III: Late post-engraftment (>100 days)

• Chronic GVHD: Major concern
• Encapsulated bacteria: Due to functional asplenia
• Varicella-zoster virus: Reactivation common

Specific Infectious Complications

CMV Disease

• Timeline: 30-100 days post-BMT
• High risk: CMV+ recipient or donor
• Manifestations: Pneumonitis, gastroenteritis, retinitis

Interstitial Pneumonitis (IP)

• Peak incidence: ~7th week (50 days) post-BMT
• Types:
  • CMV pneumonitis (most common infectious cause)
  • Idiopathic IP
  • Pneumocystis pneumonia
• Mortality: High, especially CMV pneumonitis

Prophylactic Strategies

• Antibacterial: Fluoroquinolones
• Antifungal: Fluconazole or newer azoles
• Antiviral: Acyclovir for HSV/VZV
• PCP prophylaxis: Trimethoprim-sulfamethoxazole
• CMV monitoring: Pre-emptive therapy based on viral load

GVHD Prevention

• Immunosuppression: Methotrexate + calcineurin inhibitors
• T-cell depletion: In some protocols
• HLA matching: Reduces risk significantly

• Gingival Conditions:
  • Pregnancy gingivitis: Bleeding.
  • Desquamative gingivitis: Fiery red, painful sloughing.
  • Gingival hyperplasia: Most commonly caused by phenytoin.
  • Gingival enlargement covering 3/4 of tooth: Grade III.
• ANUG:
  • Organism: Spirochetes.
  • Seen in: Young adults.
  • First-day management: Avoid deep scaling.
  • Stages: Superficial zone = bacterial contamination.
• Granulomatous Lesion: Pyogenic granuloma.
• Gingival Recession: Most commonly due to traumatic brushing.

🧂 Sodium Imbalance

• SIADH: Hyponatremia, convulsions
• Osmotic demyelination syndrome → too rapid correction
• Pseudohyponatremia: Seen in hyperlipidemia

⚖️ Acid-Base Disorders

• Normal pH: 7.36 – 7.44
• Metabolic alkalosis seen in mineralocorticoid excess

COPD

• Reid's index: Used in chronic bronchitis
• Emphysema features: ↓DLCO, weight loss, pneumothorax risk
• Chronic bronchitis: Polycythemia
• GOLD criteria: COPD severity assessment
• BODE index: Lung transplant evaluation

Sleep Apnea

Definition: Breathing pause ≥10 seconds during sleep

ASTHMA

Diagnosis & Pathophysiology

• Best diagnostic test: Demonstration of reversible obstruction
• Small airways involved
• Idiosyncratic asthma: Normal IgE levels
• Aspirin-sensitive asthma: Associated with nasal polyps

Key Points

• Charcot-Leyden crystals: Eosinophil granules
• Nebulizer droplet size: <2.5 μm
• Most severe attack indicator: Bradycardia
• Montelukast: NOT useful in acute bronchial asthma