NEET MDS Lessons
General Medicine
- Least risk site: Atrial septal defect
- IV drug user: Tricuspid valve affected
- Common organism: Staph aureus
- Late prosthetic valve endocarditis: CoNS
- Signs:
- Osler’s nodes – Palms & soles
- Roth spots – Retinal hemorrhage
- Best test: Echocardiography
- Criteria: Duke’s
- Dental prophylaxis: Amoxicillin
Stage 1: Initial Lesion
- 2 – 4 days after plaque accumulation
Stage 2: Early Lesion
- Timeline: 4 – 7 days after plaque accumulation
- T – lymphocyte dominance
Stage 3: Established Lesion
- Characteristic: Plasma cells and B – lymphocytes dominance
Bleeding on Probing (BOP)
- Appears earlier than visual signs
- Absence = good negative predictor of attachment loss
Necrotizing Ulcerative Gingivitis (NUG)
Necrotizing Ulcerative Gingivitis (NUG), also known as Vincent's disease or trench mouth, is a severe form of periodontal disease characterized by the sudden onset of symptoms and specific clinical features.
Etiology and Predisposing Factors
- Sudden Onset: NUG is characterized by a rapid onset of symptoms, often following debilitating diseases or acute respiratory infections.
- Lifestyle Factors: Changes in living habits, such as prolonged work without adequate rest, poor nutrition, tobacco use, and psychological stress, are frequently noted in patient histories .
- Smoking: Smoking has been identified as a significant predisposing factor for NUG/NDP .
- Immune Compromise: Conditions that compromise the immune system, such as poor oral hygiene, smoking, and emotional stress, are major contributors to the development of NUG .
Clinical Presentation
- Symptoms: NUG presents with:
- Punched-out, crater-like depressions at the crest of interdental papillae.
- Marginal gingival involvement, with rare extension to attached gingiva and oral mucosa.
- Grey, pseudomembranous slough covering the lesions.
- Spontaneous bleeding upon slight stimulation of the gingiva.
- Fetid odor and increased salivation.
Microbiology
- Mixed Bacterial Infection: NUG is caused by a complex
of anaerobic bacteria, often referred to as the fusospirochetal complex,
which includes:
- Treponema vincentii
- Treponema denticola
- Treponema macrodentium
- Fusobacterium nucleatum
- Prevotella intermedia
- Porphyromonas gingivalis
Treatment
-
Control of Acute Phase:
- Clean the wound with an antibacterial agent.
- Irrigate the lesion with warm water and 5% vol/vol hydrogen peroxide.
- Prescribe oxygen-releasing mouthwash (e.g., hydrogen peroxide DPF, sodium perborate DPF) to be used thrice daily.
- Administer oral metronidazole for 3 to 5 days. If sensitive to metronidazole, prescribe penicillin; if sensitive to both, consider erythromycin or clindamycin.
- Use 2% chlorhexidine in select cases for a short duration.
-
Management of Residual Condition:
- Remove predisposing local factors (e.g., overhangs).
- Perform supra- and subgingival scaling.
- Consider gingivoplasty to correct any residual gingival deformities.
🧪 GERD & Barrett’s Esophagus
| Feature | Insight |
|---|---|
| Diagnosis | Intestinal metaplasia |
| Sequelae | Stricture, adenocarcinoma |
| Risk classification | Premalignant |
| Cancer association | Esophageal adenocarcinoma |
🧫 Peptic Ulcer
- Commonest site: Duodenal bulb (1st part)
- Most frequent complication: Hemorrhage
- Best residual H. pylori test: Urea breath test
- Treatment for Zollinger – Ellison syndrome: PPI
- 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.
Morphological Classification
Three-Wall Defect (Intrabony Defect)
- Description: Defect contained by three bony walls
- Prognosis: Best regenerative potential
- Treatment: Ideal candidate for GTR procedures
Two-Wall Defect (Crater)
- Description: Defect between two adjacent teeth
- Characteristics: Interdental bone loss
- Prevalence: Most common osseous defect in chronic periodontitis
One-Wall Defect (Hemiseptum)
- Description: Defect with only one remaining bony wall
- Prognosis: Poorest regenerative potential
- Treatment: Often requires resective therapy
Bone Loss Patterns
Horizontal Bone Loss
- Associated Pocket Type: Suprabony pocket
- Pattern: Uniform reduction in alveolar bone height
- Radiographic Appearance: Horizontal radiolucency
Vertical/Angular Bone Loss
- Associated Pocket Type: Infrabony pocket
- Pattern: Uneven bone destruction
- Clinical Significance: More complex treatment requirements
Microbes in Periodontics
Bacteria Associated with Periodontal Health
-
Primary Species:
- Gram-Positive Facultative Bacteria:
- Streptococcus:
- S. sanguis
- S. mitis
- A. viscosus
- A. naeslundii
- Actinomyces:
- Beneficial for maintaining periodontal health.
- Streptococcus:
- Gram-Positive Facultative Bacteria:
-
Protective or Beneficial Bacteria:
- Key Species:
- S. sanguis
- Veillonella parvula
- Corynebacterium ochracea
- Characteristics:
- Found in higher numbers at inactive periodontal sites (no attachment loss).
- Low numbers at sites with active periodontal destruction.
- Prevent colonization of pathogenic microorganisms (e.g., S. sanguis produces peroxide).
- Key Species:
-
Clinical Relevance:
- High levels of C. ochracea and S. sanguis are associated with greater attachment gain post-therapy.
Microbiology of Chronic Plaque-Induced Gingivitis
-
Composition:
- Roughly equal proportions of:
- Gram-Positive: 56%
- Gram-Negative: 44%
- Facultative: 59%
- Anaerobic: 41%
- Roughly equal proportions of:
-
Predominant Gram-Positive Species:
- S. sanguis
- S. mitis
- S. intermedius
- S. oralis
- A. viscosus
- A. naeslundii
- Peptostreptococcus micros
-
Predominant Gram-Negative Species:
- Fusobacterium nucleatum
- Porphyromonas intermedia
- Veillonella parvula
- Haemophilus spp.
- Capnocytophaga spp.
- Campylobacter spp.
-
Pregnancy-Associated Gingivitis:
- Increased levels of steroid hormones and P. intermedia.
Chronic Periodontitis
-
Key Microbial Species:
- High levels of:
- Porphyromonas gingivalis
- Bacteroides forsythus
- Porphyromonas intermedia
- Campylobacter rectus
- Eikenella corrodens
- Fusobacterium nucleatum
- Actinobacillus actinomycetemcomitans
- Peptostreptococcus micros
- Treponema spp.
- Eubacterium spp.
- High levels of:
-
Pathogenic Mechanisms:
- P. gingivalis and A. actinomycetemcomitans can invade host tissue cells.
- Viruses such as Epstein-Barr Virus-1 (EBV-1) and human cytomegalovirus (HCMV) may contribute to bone loss.
Localized Aggressive Periodontitis
- Microbiota Characteristics:
- Predominantly gram-negative, capnophilic, and anaerobic rods.
- Almost all localized juvenile periodontitis (LJP) sites harbor A. actinomycetemcomitans, which can comprise up to 90% of the total cultivable microbiota.