NEET MDS Lessons
General Medicine
Blade Angulation Protocols
Scaling & Root Planing
- Angulation: 45-90 degrees to tooth surface
- Purpose: Effective calculus removal and root surface debridement
Gingival Curettage
- Angulation: >90 degrees
- Technique: Removal of infected soft tissue from pocket wall
Curette Sharpening
- Optimal Angle: 100-110 degrees
- Maintenance: Critical for effective instrumentation
Curette Design
Gracey Curettes
- Offset Angle: 60 degrees
- Specificity: Area-specific design for different tooth surfaces
Universal Curettes
- Angle: 90 degrees
- Application: Suitable for all tooth surfaces
After-Five Curettes
- Modification: Terminal shank extended by 3mm
- Purpose: Access to deep pockets (>5mm)
Probing Systems
CPITN Probe
- Tip Diameter: 0.5mm
- Markings: 3.5, 5.5, 8.5, 11.5mm
- Use: Community periodontal index assessment
Florida Probe
- Tip Diameter: 0.4mm (more precise)
- Technology: Computerized probing system
Implant Probing
- Maximum Force: 25N
- Probe Type: Plastic probes recommended to prevent implant surface damage
Critical Measurements
- PMN threshold: 60% in junctional epithelium → tissue detachment
- Clinical significance: Level 1 provides tangible benefit of large size
Important Ratios & Numbers
- GCF glucose: 3 – 4× serum levels
- Aggressive vs chronic periodontitis: 3 – 4× faster bone loss
- Mineralization timeline: 50% (2 days), 60 – 90% (12 days)
Fundamental Concepts
- Primary Plaque Retentive Factor: Calculus provides rough surface for bacterial adherence
- Calculus Formation Inhibitor: Pyrophosphate in toothpaste formulations
- Optimal Graft Conditions: Three-walled defects offer best regenerative potential
- Highest Osteogenic Potential: Autogenous cancellous bone grafts
Diagnostic Standards
- Halitosis Gold Standard: Organoleptic analysis (human nose assessment)
- Furcation Vulnerability: Most susceptible to trauma from excessive occlusal forces
- Worst Furcation Prognosis: Maxillary first premolar due to root proximity
Risk Factors and Prevention
- Leading Cause of Recession: Traumatic toothbrushing techniques
- Root Caries Organism: Actinomyces viscosus
- Most Preventable Risk Factor: Smoking cessation offers greatest improvement in treatment outcomes
Important Periodontal Indices
PMA Index
- Purpose: Assessment of gingival disease status
- Components: Papillary (P), Marginal (M), and Attached (A) gingiva scoring
Ramfjord Index
- Selected Teeth: 16, 21, 24, 36, 41, 44
- Rationale: Representative sampling of entire dentition
Merin's Classification
- Application: Patient recall scheduling based on periodontal status
- Categories: Maintenance intervals based on disease severity
Clinical Measurements
Gingival Sulcus Depth
- Primary Teeth: 1-2mm (shallower than permanent teeth)
- Permanent Teeth: 2-3mm in health
Level of Attachment
- Definition: Distance from cementoenamel junction (CEJ) to pocket base
- Clinical Significance: True measure of periodontal support loss
Fremitus Test
- Purpose: Diagnosis of tooth mobility
- Technique: Palpation during functional movements
High-Yield Numbers
- FBS ≥126 mg/dL (DM diagnosis)
- HbA1C >6.5% (DM diagnosis)
- IGT: 140-199 mg/dL (2-hr GTT)
- Sleep apnea: ≥10 seconds
- Cortisol <3 mg/dL (Addison's)
- ACTH >200 pg/mL (Addison's)
- Nebulizer droplets <2.5 μm
Remember the "Onlys"
- Telmisartan: Only ARB with PPAR-γ activity
- Microalbuminuria: Most reliable diabetic nephropathy marker
- TB: Most common cause of adrenal insufficiency in India
- Melanoma: Most common primary tumor → adrenal mets
Classic Associations
- Type 1 DM: HLA-DR3/DR4, Anti-GAD antibodies
- Aspirin asthma: Nasal polyps
- Emphysema: Weight loss, pneumothorax, ↓DLCO
- Chronic bronchitis: Polycythemia, Reid's index
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.
- Chlorhexidine:
- Minimum: 0.12%; Optimum: 0.2%.
- Chip degrades in 7 – 10 days.
- Floss & Brushes:
- Preferred floss: Unwaxed thin.
- Floss length: 12 – 18 inches.
- Toothbrush: 2 – 4 rows, 5 – 12 tufts per row.
- Soft bristle diameter: 0.2 mm.
- Powered Brushes: Invented in 1939; use oscillating/rotating motion.
- Fones Technique: Circular brushing method.
- Antiplaque Agents:
- Bisbiguanides: 2nd generation.
- Pyrophosphate: Inhibits calculus formation.