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)

• 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.

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

Calculus Composition

• Brushite: More common in mandibular anterior
• Magnesium whitlockite: More common in posterior
• Ca:P ratio: Higher subgingivally
• Mineralization: 50% in 2 days, 60 – 90% in 12 days

Microbiology

• First colonizers: S. salivarius and S. mitis
• Red complex: P. gingivalis, T. denticola, T. forsythia (cause BOP)
• Growth enhancement: P. gingivalis grows better with succinate (C. ochracea) and protoheme (C. rectus)

Pellicle Structure

• Basal layer: Thin, difficult to remove
• Globular layer: 1 μm thick, easier to detach

Bacterial Recognition

• Gram positive: Activate TLR2 → IL – 8
• Gram negative: Activate TLR4 → TNF – α

Dark Field Microscopy in Periodontal Microbiology

Dark field microscopy and phase contrast microscopy are valuable techniques in microbiological studies, particularly in the field of periodontal research. These methods allow for the direct observation of bacteria in plaque samples, providing insights into their morphology and motility. .

Dark Field Microscopy

• Definition: Dark field microscopy is a technique that enhances the contrast of unstained, transparent specimens, allowing for the visualization of live microorganisms in their natural state.
• Principle: The method uses a special condenser that directs light at an angle, creating a dark background against which the specimen appears bright. This allows for the observation of motility and morphology without the need for staining.

Applications in Periodontal Microbiology

1. Alternative to Culture Methods:

   • Dark field microscopy has been suggested as a rapid alternative to traditional culture methods for assessing bacterial populations in periodontal plaque samples. It allows for immediate observation of bacteria without the time-consuming process of culturing.

2. Assessment of Morphology and Motility:

   • The technique enables direct and rapid assessment of the morphology (shape and structure) and motility (movement) of bacteria present in plaque samples. This information can be crucial for understanding the dynamics of periodontal disease.

3. Indication of Periodontal Disease Status:

   • Dark field microscopy has been used to indicate the status of periodontal disease and the effectiveness of maintenance programs. By observing the presence and activity of specific bacteria, clinicians can gain insights into the health of periodontal tissues.

Limitations of Dark Field Microscopy

1. Analysis of Major Periodontal Pathogens:

   • While dark field microscopy can visualize motile bacteria, it is important to note that many major periodontal pathogens, such as Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Bacteroides forsythus, Eikenella corrodens, and Eubacterium species, are motile. However, the technique may not provide detailed information about their specific characteristics or pathogenic potential.

2. Differentiation of Treponema Species:

   • Dark field microscopy cannot differentiate between species of Treponema, which is a limitation when identifying specific pathogens associated with periodontal disease. This lack of specificity can hinder the ability to tailor treatment based on the exact microbial profile.

3. Limited Quantitative Analysis:

   • While dark field microscopy allows for qualitative observations, it may not provide quantitative data on bacterial populations, which can be important for assessing disease severity and treatment outcomes.

⚛️ Hodgkin’s Disease

• Most common subtype: Nodular sclerosis
• Common in India: Mixed cellularity

🧬 Non-Hodgkin’s Lymphoma

• Classification: REAL
• Burkitt lymphoma: Most malignant; t(8;14) & t(2;8) translocations
• EBV association noted
• Angiocentric lymphoma: Non – B-cell