NEET MDS Lessons
Periodontology
🧬 Risk Factors
- Increased homocysteine levels
- Raised lipoprotein(a)
- Nephrotic syndrome increases CAD risk
- Unsaturated fatty acid intake: Protective
- Best probability predictor in elderly: LDL/HDL ratio
⚕️ Diagnosis & Presentation
| Condition | Diagnostic Best Practice |
|---|---|
| Angina pectoris | History |
| Stable angina | Cardiac markers unchanged |
| Acute MI | Tall T wave (earliest ECG sign) |
| MI ≥12 hrs post-onset | Test of choice: Cardiac troponin |
| Prinzmetal’s angina | First-line agent: Nitrates |
| Intraoperative MI | Transesophageal echocardiography |
| Best biomarker of MI | Troponin T |
| WHO MI criteria | Echo not part of official criteria |
🧪 Enzymes & Drugs
- Enzyme ↑ at 4 – 6 hrs, ↓ in 3 – 4 days: CPK
- Stress ECHO agent: Dobutamine
- Intervention of choice: Streptokinase + Heparin
- Thrombolytics window: Within 12 hrs of MI
🚨 Prognosis & Complications
- Day 1: Maximum MI mortality
- Post-MI valvular lesion: Mitral regurgitation
- Best predictor of morbidity: LVEF
- Fatal thrombolysis complication: Intracranial hemorrhage
- LAD artery nicknamed: Widow’s artery
🔻 Anemia Types
🔸 Microcytic
| Type | Features |
|---|---|
| Thalassemia | Microcytic hypochromic RBCs |
| IDA | ↓ ferritin, ↑ TIBC; ↓ bone marrow iron first |
| Hemochromatosis | ↑ ferritin, ↑ iron, ↑ transferrin sat |
| HUS | Fragmented RBCs |
🔸 Macrocytic
- Pernicious anemia: ↓ intrinsic factor
- MCH ↑, MCHC normal
- Hypokalemia during treatment
- Causes: Dietary folate deficiency, celiac disease
- Thiamine deficiency → Lactic acidosis
🔸 Sideroblastic
- Causes: Hypothyroidism, INH therapy
- Treatment: Pyridoxine
- Genetic variant: Pearson syndrome
Periodontal Fibers
Periodontal fibers play a crucial role in maintaining the integrity of the periodontal ligament and supporting the teeth within the alveolar bone. Understanding the different groups of periodontal fibers is essential for comprehending their functions in periodontal health and disease.
1. Gingivodental Group
- Location:
- Present on the facial, lingual, and interproximal surfaces of the teeth.
- Attachment:
- These fibers are embedded in the cementum just beneath the epithelium at the base of the gingival sulcus.
- Function:
- They help support the gingiva and maintain the position of the gingival margin.
2. Circular Group
- Location:
- These fibers course through the connective tissue of the marginal and interdental gingiva.
- Attachment:
- They encircle the tooth in a ring-like fashion.
- Function:
- The circular fibers help maintain the contour of the gingiva and provide support to the marginal gingiva.
3. Transseptal Group
- Location:
- Located interproximally, these fibers extend between the cementum of adjacent teeth.
- Attachment:
- They lie in the area between the epithelium at the base of the gingival sulcus and the crest of the interdental bone.
- Function:
- The transseptal fibers are primarily responsible for the post-retention relapse of orthodontically positioned teeth.
- They are sometimes classified as principal fibers of the periodontal ligament.
- Collectively, they form the interdental ligament of the arch, providing stability to the interproximal areas.
4. Semicircular Fibers
- Location:
- These fibers attach to the proximal surface of a tooth immediately below the cementoenamel junction (CEJ).
- Attachment:
- They go around the facial or lingual marginal gingiva of the tooth and attach to the other proximal surface of the same tooth.
- Function:
- Semicircular fibers help maintain the position of the tooth and support the gingival tissue around it.
5. Transgingival Fibers
- Location:
- These fibers attach to the proximal surface of one tooth and traverse the interdental space diagonally to attach to the proximal surface of the adjacent tooth.
- Function:
- Transgingival fibers provide support across the interdental space, helping to maintain the position of adjacent teeth and the integrity of the gingival tissue.
Gingival Crevicular Fluid (GCF) is a serum-like exudate found in the gingival sulcus. Initially considered a transudate in healthy gingiva, it transitions to an inflammatory exudate during disease states. GCF serves as a valuable diagnostic medium due to its dynamic composition, reflective of periodontal status.
Composition of GCF
GCF contains a variety of biochemical and cellular components that mirror periodontal health:
| Component | Characteristics & Clinical Importance |
|---|---|
| Glucose | 3–4 times higher than serum levels, indicating microbial metabolism and inflammation |
| Proteins | Albumin, IgG, enzymes like elastase, collagenase, myeloperoxidase |
| Electrolytes | Sodium, potassium, calcium — influence osmotic balance and tissue response |
| Cytokines | IL-1β, TNF-α, IL-6 — markers of inflammation and bone resorption |
| Prostaglandins | PGE2 — associated with tissue destruction and inflammation |
| Lymphocytes | T:B ratio is reversed (1:3) compared to serum (3:1), reflecting immune modulation |
| Microbial Products | Lipopolysaccharides, enzymes from plaque — triggers host response |
| Metabolic Products | Lactate, pyruvate — indicators of anaerobic bacterial activity |
- Plaque Biofilm:
- Quorum sensing: bacterial communication
- Co-aggregation: Gram-negative adherence
- Microbial Shift (Health → Disease):
- Facultative → Obligate anaerobes
- Fermenting → Proteolytic
- Cocci → Rods
- Non-motile → Motile
- Immunoglobulins:
- Saliva: IgA
- GCF: IgG
- Interleukins & MMPs:
- IL-1β: Most potent bone-destructive cytokine
- MMP-8 & MMP-1: Collagenases
- MMP-2 & MMP-9: Gelatinases
- Activated by neutrophil proteases (e.g., cathepsin G)
- MAP formula: Diastolic + 1/3 Pulse Pressure
- Pulse Pressure: Systolic – Diastolic
- Sphygmomanometer readings: Slightly higher than intra-arterial
- J Curve Phenomenon: Excessive BP lowering → adverse cardiac events
- Best drug for angina with HTN: Metoprolol
- Contraindicated in diabetic HTN: Thiazides
- ACEI side effect: Hyperkalemia
- Aliskiren: Direct renin antagonist
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)