NEET MDS Lessons
Periodontology
| Virus | Key Info |
|---|---|
| Hepatitis E | Feco-oral spread; pregnancy = high mortality |
| Hepatitis B |
- Perinatal transmission (90%)
- Window phase: HBsAg ↓, anti-HBs ↑
- Infectivity: HBsAg + HBeAg
- First marker post-infection: HBsAg
- IgM anti-HBc = acute infection
- Reverse transcriptase → P gene
| Hepatitis C | Most chronic & linked to liver disease
| Hepatitis A | Prophylaxis: Human IgG
| Hepatitis E | Most epidemic-prone in India
| Councilman bodies | Seen in acute viral hepatitis
Hormonal Effects on Periodontal Tissues
Optimal Treatment Timing
- Safest Period: Early second trimester (weeks 14-20)
- Rationale: Organogenesis complete, uterine size manageable
Clinical Manifestations
- Most Striking Feature: Pronounced ease of bleeding (pregnancy gingivitis)
- Mechanism: Increased vascular permeability due to hormonal changes
Microbial Changes
- Bacterial Shift: Increased Prevotella intermedia
- Hormonal Influence: Estrogen and progesterone serve as growth factors for certain bacteria
Treatment Phases
- Phase 1: Non – surgical
- Phase 2: Surgical
- Phase 3: Restorative
- Phase 4: Maintenance Must progress through Phase 1 → 4 before Phase 2 or 3
Merin's Classification
- Class A: 6 months – 1 year recall
- Class B: 3 – 4 months recall
- Class C: 1 – 3 months recall
Iodine Effects
- High dose, short period → Inhibits T4 synthesis (Wolff-Chaikoff effect)
- Low dose, long period → Increases T4 synthesis (Jod-Basedow effect)
Drugs Inhibiting T4→T3 Conversion
Propranolol, Dexamethasone, Propylthiouracil, High-dose iodine, Radiographic contrast
Hypothyroidism
- Best test: Raised TSH (primary hypothyroidism)
- Causes: Amyloidosis, Sarcoidosis, Hemochromatosis, Scleroderma, Cystinosis
- Drugs: Amiodarone, Lithium
- Hashimoto thyroiditis
Cushing's Syndrome
- Earliest feature: Loss of diurnal variation of cortisol
- High-dose dexamethasone suppression test: Differentiates pituitary adenoma vs ectopic ACTH
Adrenal Insufficiency (Addison's Disease)
- Most common cause in India: Tuberculosis
- Most common primary tumor metastasizing to adrenals: Melanoma
- Most confirmatory test: ACTH stimulation test
- Diagnostic: Low plasma cortisol (<3 mg/dL) at 8 AM + elevated ACTH (>200 pg/mL)
- Most common symptom: Asthenia (due to hypotension & hypoglycemia)
- GTR Membrane Placement:
- Apical border: 3 – 4 mm below defect margin.
- Lateral extension: 2 – 3 mm beyond defect.
- Root Surface Biomodification: Citric acid (pH 1.0) for 2 – 5 min.
- Enamel Matrix Derivative: Emdogain (from porcine teeth).
- Cervical Enamel Projections: Seen in 8.6 – 28.6% of molars.
- Smoking: Preventable risk factor; damages cilia via hydrogen cyanide.
Epithelium Types
- Parakeratinized: Retains pyknotic nuclei in stratum corneum
- Orthokeratinized: No nuclei in stratum corneum
- Keratinization order: Palate > Gingiva > Tongue > Cheek (most to least)
Keratin Distribution
- K 1, 2, 10, 12: Orthokeratinized areas
- K 6, 16: Highly proliferative areas
- K 5, 14: Stratification specific
- K 19: Parakeratinized areas
Structural Components
- Stratum spinosum: Contains keratinosomes/Odland bodies (modified lysosomes)
- Basal lamina: 300 – 400 Å thick, joins epithelium to
connective tissue
- Lamina lucida (rich in laminin)
- Lamina densa (rich in collagen type IV)
- Junctional epithelium: 0.25 – 1.35 mm long, formed by oral + reduced enamel epithelium
Clinical Probing
- Normal probing depth: 2 – 3 mm (requires apical penetration)
- Stippling: Orange peel appearance, restricted to attached gingiva
- Loss of stippling: Early sign of gingivitis