Microbes in Periodontics

Bacteria Associated with Periodontal Health

• Primary Species:

  • Gram-Positive Facultative Bacteria:
    • Streptococcus:
      • S. sanguis
      • S. mitis
      • A. viscosus
      • A. naeslundii
    • Actinomyces:
      • Beneficial for maintaining periodontal health.

• Protective or Beneficial Bacteria:

  • Key Species:
    • S. sanguis
    • Veillonella parvula
    • Corynebacterium ochracea
  • Characteristics:
    • Found in higher numbers at inactive periodontal sites (no attachment loss).
    • Low numbers at sites with active periodontal destruction.
    • Prevent colonization of pathogenic microorganisms (e.g., S. sanguis produces peroxide).

• Clinical Relevance:

  • High levels of C. ochracea and S. sanguis are associated with greater attachment gain post-therapy.

Microbiology of Chronic Plaque-Induced Gingivitis

• Composition:

  • Roughly equal proportions of:
    • Gram-Positive: 56%
    • Gram-Negative: 44%
    • Facultative: 59%
    • Anaerobic: 41%

• Predominant Gram-Positive Species:

  • S. sanguis
  • S. mitis
  • S. intermedius
  • S. oralis
  • A. viscosus
  • A. naeslundii
  • Peptostreptococcus micros

• Predominant Gram-Negative Species:

  • Fusobacterium nucleatum
  • Porphyromonas intermedia
  • Veillonella parvula
  • Haemophilus spp.
  • Capnocytophaga spp.
  • Campylobacter spp.

• Pregnancy-Associated Gingivitis:

  • Increased levels of steroid hormones and P. intermedia.

Chronic Periodontitis

• Key Microbial Species:

  • High levels of:
    • Porphyromonas gingivalis
    • Bacteroides forsythus
    • Porphyromonas intermedia
    • Campylobacter rectus
    • Eikenella corrodens
    • Fusobacterium nucleatum
    • Actinobacillus actinomycetemcomitans
    • Peptostreptococcus micros
    • Treponema spp.
    • Eubacterium spp.

• Pathogenic Mechanisms:

  • P. gingivalis and A. actinomycetemcomitans can invade host tissue cells.
  • Viruses such as Epstein-Barr Virus-1 (EBV-1) and human cytomegalovirus (HCMV) may contribute to bone loss.

Localized Aggressive Periodontitis

• Microbiota Characteristics:
  • Predominantly gram-negative, capnophilic, and anaerobic rods.
  • Almost all localized juvenile periodontitis (LJP) sites harbor A. actinomycetemcomitans, which can comprise up to 90% of the total cultivable microbiota.

⚙️ Renal Disorders

• Acute Kidney Injury:
  • Pre-renal causes: Dehydration, blood loss
  • Post-renal: Obstruction (e.g., stones, tumors)
• Nephrotic Syndrome:
  • ↑ susceptibility to CAD
  • Hallmarks: Proteinuria, hypoalbuminemia, edema, hyperlipidemia

🧪 Electrolytes & Acid-Base

• Hyperkalemia:
  • Side effect of: ACE inhibitors
  • ECG: Tall T waves, widened QRS
• Hyponatremia:
  • Watch for CNS symptoms
  • SIADH common cause in small cell lung CA

💉 Drugs & Renal Impact

Dental Plaque

Dental plaque is a biofilm that forms on the surfaces of teeth and is composed of a diverse community of microorganisms. The development of dental plaque occurs in stages, beginning with primary colonizers and progressing to secondary colonization and plaque maturation.

Primary Colonizers

• Timeframe:
  • Acquired within a few hours after tooth cleaning or exposure.
• Characteristics:
  • Predominantly gram-positive facultative microbes.
• Key Species:
  • Actinomyces viscosus
  • Streptococcus sanguis
• Adhesion Mechanism:
  • Primary colonizers adhere to the tooth surface through specific adhesins.
  • For example, A. viscosus possesses fimbriae that bind to proline-rich proteins in the dental pellicle, facilitating initial attachment.

Secondary Colonization and Plaque Maturation

• Microbial Composition:
  • As plaque matures, it becomes predominantly populated by gram-negative anaerobic microorganisms.
• Key Species:
  • Prevotella intermedia
  • Prevotella loescheii
  • Capnocytophaga spp.
  • Fusobacterium nucleatum
  • Porphyromonas gingivalis
• Coaggregation:
  • Coaggregation refers to the ability of different species and genera of plaque microorganisms to adhere to one another.
  • This process occurs primarily through highly specific stereochemical interactions of protein and carbohydrate molecules on cell surfaces, along with hydrophobic, electrostatic, and van der Waals forces.

Plaque Hypotheses

1. Specific Plaque Hypothesis:

   • This hypothesis posits that only certain types of plaque are pathogenic.
   • The pathogenicity of plaque depends on the presence or increase of specific microorganisms.
   • It predicts that plaque harboring specific bacterial pathogens leads to periodontal disease due to the production of substances that mediate the destruction of host tissues.

2. Nonspecific Plaque Hypothesis:

   • This hypothesis maintains that periodontal disease results from the overall activity of the entire plaque microflora.
   • It suggests that the elaboration of noxious products by the entire microbial community contributes to periodontal disease, rather than specific pathogens alone.

Modified Gingival Index (MGI)

The Modified Gingival Index (MGI) is a clinical tool used to assess the severity of gingival inflammation. It provides a standardized method for evaluating the health of the gingival tissues, which is essential for diagnosing periodontal conditions and monitoring treatment outcomes. Understanding the scoring criteria of the MGI is crucial for dental professionals in their assessments.

Scoring Criteria for the Modified Gingival Index (MGI)

The MGI uses a scale from 0 to 4 to classify the degree of gingival inflammation. Each score corresponds to specific clinical findings:

1. Score 0: Absence of Inflammation

   • Description: No signs of inflammation are present in the gingival tissues.
   • Clinical Significance: Indicates healthy gingiva with no bleeding or other pathological changes.

2. Score 1: Mild Inflammation

   • Description:
     • Slight change in color (e.g., slight redness).
     • Little change in texture of any portion of the marginal or papillary gingival unit, but not affecting the entire unit.
   • Clinical Significance: Suggests early signs of gingival inflammation, which may require monitoring and preventive measures.

3. Score 2: Mild Inflammation (Widespread)

   • Description:
     • Similar criteria as Score 1, but involving the entire marginal or papillary gingival unit.
   • Clinical Significance: Indicates a more widespread mild inflammation that may necessitate intervention to prevent progression.

4. Score 3: Moderate Inflammation

   • Description:
     • Glazing of the gingiva.
     • Redness, edema, and/or hypertrophy of the marginal or papillary gingival unit.
   • Clinical Significance: Reflects a moderate level of inflammation that may require active treatment to reduce inflammation and restore gingival health.

5. Score 4: Severe Inflammation

   • Description:
     • Marked redness, edema, and/or hypertrophy of the marginal or papillary gingival unit.
     • Presence of spontaneous bleeding, congestion, or ulceration.
   • Clinical Significance: Indicates severe gingival disease that requires immediate intervention and may be associated with periodontal disease.

Clinical Application of the MGI

1. Assessment of Gingival Health:

   • The MGI provides a systematic approach to evaluate gingival health, allowing for consistent documentation of inflammation levels.

2. Monitoring Treatment Outcomes:

   • Regular use of the MGI can help track changes in gingival health over time, assessing the effectiveness of periodontal treatments and preventive measures.

3. Patient Education:

   • The MGI can be used to educate patients about their gingival health status, helping them understand the importance of oral hygiene and regular dental visits.

4. Research and Epidemiological Studies:

   • The MGI is often used in clinical research to evaluate the prevalence and severity of gingival disease in populations.

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