NEET MDS Lessons
General Medicine
Calculus Composition
- Brushite: More common in mandibular anterior
- Magnesium whitlockite: More common in posterior
- Ca:P ratio: Higher subgingivally
- Mineralization: 50% in 2 days, 60 – 90% in 12 days
Microbiology
- First colonizers: S. salivarius and S. mitis
- Red complex: P. gingivalis, T. denticola, T. forsythia (cause BOP)
- Growth enhancement: P. gingivalis grows better with succinate (C. ochracea) and protoheme (C. rectus)
Pellicle Structure
- Basal layer: Thin, difficult to remove
- Globular layer: 1 μm thick, easier to detach
Bacterial Recognition
- Gram positive: Activate TLR2 → IL – 8
- Gram negative: Activate TLR4 → TNF – α
| Disorder | Marker/Feature |
|---|---|
| Hyperkalemia | Tall P wave on ECG |
| Leukemia | Pseudo-hyperkalemia |
| Hypokalemia | Can occur with B12 therapy |
| Calcium Gluconate | Stabilizes myocardium; doesn't lower K⁺ |
🧂 Sodium Imbalance
- SIADH: Hyponatremia, convulsions
- Osmotic demyelination syndrome → too rapid correction
- Pseudohyponatremia: Seen in hyperlipidemia
⚖️ Acid-Base Disorders
| Type | Diagnostic Feature |
|---|---|
| Metabolic Acidosis | ↓ HCO₃⁻ |
| Metabolic Alkalosis | ↑ HCO₃⁻ |
| Respiratory Acidosis | ↑ CO₂ |
| Respiratory Alkalosis | ↓ CO₂ |
- Normal pH: 7.36 – 7.44
- Metabolic alkalosis seen in mineralocorticoid excess
- Budd-Chiari:
- Cause: PNH or Polycythemia vera
- Common site: Hepatic veins
- Wilson Disease:
- Autosomal recessive < age 40
- Excess copper in liver + brain
Assessing New Attachment in Periodontal Therapy
Assessing new attachment following periodontal therapy is crucial for evaluating treatment outcomes and understanding the healing process. However, various methods of assessment have limitations that must be considered.
1. Periodontal Probing
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Assessment Method: Periodontal probing is commonly used to measure probing depth and attachment levels before and after therapy.
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Limitations:
- Coronal Positioning of Probe Tip: After therapy, when the inflammatory lesion is resolved, the probe tip may stop coronal to the apical termination of the epithelium. This can lead to misleading interpretations of attachment gain.
- Infrabony Defects: Following treatment of infrabony defects, new bone may form so close to the tooth surface that the probe cannot penetrate. This can result in a false impression of improved attachment levels.
- Interpretation of Results: A gain in probing attachment level does not necessarily indicate a true gain of connective tissue attachment. Instead, it may reflect improved health of the surrounding tissues, which increases resistance to probe penetration.
2. Radiographic Analysis and Reentry Operations
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Assessment Method: Radiographic analysis involves comparing radiographs taken before and after therapy to evaluate changes in bone levels. Reentry operations allow for direct inspection of the treated area.
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Limitations:
- Bone Fill vs. New Attachment: While radiographs can provide evidence of new bone formation (bone fill), they do not document the formation of new root cementum or a new periodontal ligament. Therefore, radiographic evidence alone cannot confirm the establishment of new attachment.
3. Histologic Methods
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Assessment Method: Histologic analysis involves examining tissue samples under a microscope to assess the formation of new attachment, including new cementum and periodontal ligament.
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Advantages:
- Validity: Histologic methods are considered the only valid approach to assess the formation of new attachment accurately.
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Limitations:
- Pre-Therapy Assessment: Accurate assessment of the attachment level prior to therapy is essential for histologic analysis. If the initial attachment level cannot be determined with certainty, it may compromise the validity of the findings.
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)
Junctional Epithelium
The junctional epithelium (JE) is a critical component of the periodontal tissue, playing a vital role in the attachment of the gingiva to the tooth surface. Understanding its structure, function, and development is essential for comprehending periodontal health and disease.
Structure of the Junctional Epithelium
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Composition:
- The junctional epithelium consists of a collar-like band of stratified squamous non-keratinized epithelium.
- This type of epithelium is designed to provide a barrier while allowing for some flexibility and permeability.
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Layer Thickness:
- In early life, the junctional epithelium is approximately 3-4 layers thick.
- As a person ages, the number of epithelial layers can increase significantly, reaching 10 to 20 layers in older individuals.
- This increase in thickness may be a response to various factors, including mechanical stress and inflammation.
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Length:
- The length of the junctional epithelium typically ranges from 0.25 mm to 1.35 mm.
- This length can vary based on individual anatomy and periodontal health.
Development of the Junctional Epithelium
- The junctional epithelium is formed by the confluence of the oral epithelium and the reduced enamel epithelium during the process of tooth eruption.
- This fusion is crucial for establishing the attachment of the gingiva to the tooth surface, creating a seal that helps protect the underlying periodontal tissues from microbial invasion.
Function of the Junctional Epithelium
- Barrier Function: The junctional epithelium serves as a barrier between the oral cavity and the underlying periodontal tissues, helping to prevent the entry of pathogens.
- Attachment: It provides a strong attachment to the tooth surface, which is essential for maintaining periodontal health.
- Regenerative Capacity: The junctional epithelium has a high turnover rate, allowing it to regenerate quickly in response to injury or inflammation.
Clinical Relevance
- Periodontal Disease: Changes in the structure and function of the junctional epithelium can be indicative of periodontal disease. For example, inflammation can lead to increased permeability and loss of attachment.
- Healing and Repair: Understanding the properties of the junctional epithelium is important for developing effective treatments for periodontal disease and for managing healing after periodontal surgery.
Causes
- Volatile sulfur compounds: H₂S, methyl mercaptan, dimethyl sulfide
Detection Methods
- Gold standard: Organoleptic rating (easiest)
- Most sensitive: Gas chromatography