NEET MDS Lessons
Periodontology
Surgical Considerations
- Minimum implant distance: 3 mm
- Mesio – distal space for 2 implants: 14 mm
- Twist drill speed: 800 – 1500 rpm (2mm drill)
- Piezosurgery: Invented by Vercellotti, developed by Mectron
Biological Considerations
- Peri – implant biological width: 4 – 4.5 mm (epithelial attachment + supracrestal CT)
- Maximum bone loss: First 6 – 24 months post – extraction
- Bone Defects:
- Most common: Osseous craters.
- Best graft success: Three-walled defects.
- Bone graft types:
- Autogenous cancellous: Most osteogenic.
- Xenograft: From different species.
- Osteoplasty: Recontouring without removing supporting bone.
- Osteotomy: Removes supporting bone.
- Implants:
- Minimum 5 mm from mental foramen.
- Blade implants: Linkow; Cylindrical: Schroeder.
- Micro-movement >150 µm: Fibrous tissue formation.
- Connective tissue near implant: No blood vessels, many fibroblasts.
- Probing: Use plastic probes; max force = 25 N.
- Florida probe tip: 0.4 mm.
| Feature | Insight |
|---|---|
| vWD inheritance | Autosomal dominant |
| Bleeding time ↑ in vWD | Differentiates from Hemophilia A |
| Factor VIII <1% | Spontaneous bleeding in Hemophilia A |
| 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
| 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
🧬 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
Sutures for Periodontal Flaps
Suturing is a critical aspect of periodontal surgery, particularly when managing periodontal flaps. The choice of suture material can significantly influence healing, tissue adaptation, and overall surgical outcomes.
1. Nonabsorbable Sutures
Nonabsorbable sutures are designed to remain in the tissue until they are manually removed. They are often used in situations where long-term support is needed.
A. Types of Nonabsorbable Sutures
-
Silk (Braided)
- Characteristics:
- Excellent handling properties and knot security.
- Provides good tissue approximation.
- Applications: Commonly used in periodontal surgeries due to its ease of use and reliability.
- Characteristics:
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Nylon (Monofilament) (Ethilon)
- Characteristics:
- Strong and resistant to stretching.
- Less tissue reactivity compared to silk.
- Applications: Ideal for delicate tissues and areas requiring minimal tissue trauma.
- Characteristics:
-
ePTFE (Monofilament) (Gore-Tex)
- Characteristics:
- Biocompatible and non-reactive.
- Excellent tensile strength and flexibility.
- Applications: Often used in guided tissue regeneration procedures and in areas where long-term support is needed.
- Characteristics:
-
Polyester (Braided) (Ethibond)
- Characteristics:
- High tensile strength and good knot security.
- Less pliable than silk.
- Applications: Used in situations requiring strong sutures, such as in flap stabilization.
- Characteristics:
2. Absorbable Sutures
Absorbable sutures are designed to be broken down by the body over time, eliminating the need for removal. They are often used in periodontal surgeries where temporary support is sufficient.
A. Types of Absorbable Sutures
-
Surgical Gut
-
Plain Gut (Monofilament)
- Absorption Time: Approximately 30 days.
- Characteristics: Made from sheep or cow intestines; provides good tensile strength initially but loses strength quickly.
- Applications: Suitable for soft tissue approximation where rapid absorption is desired.
-
Chromic Gut (Monofilament)
- Absorption Time: Approximately 45 to 60 days.
- Characteristics: Treated with chromium salts to delay absorption; retains strength longer than plain gut.
- Applications: Used in areas where a longer healing time is expected.
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-
Synthetic Absorbable Sutures
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Polyglycolic Acid (Braided) (Vicryl, Ethicon)
- Absorption Time: Approximately 16 to 20 days.
- Characteristics: Provides good tensile strength and is absorbed predictably.
- Applications: Commonly used in periodontal and oral surgeries due to its handling properties.
-
Dexon (Davis & Geck)
- Characteristics: Similar to Vicryl; made from polyglycolic acid.
- Applications: Used in soft tissue approximation and ligation.
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Polyglycaprone (Monofilament) (Maxon)
- Absorption Time: Similar to Vicryl.
- Characteristics: Offers excellent tensile strength and is absorbed more slowly than other synthetic options.
- Applications: Ideal for areas requiring longer support during healing.
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