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PERIODONTICS - COMPLETE ANSWERS

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Q1 (10 Marks) - Macroscopic and Microscopic Features of Gingiva

MACROSCOPIC FEATURES

• Surrounds the tooth like a collar; not attached to tooth surface
• Extends from gingival margin to the free gingival groove
• Width: approximately 1 mm
• Forms the soft tissue wall of the gingival sulcus
• The gingival sulcus depth is 0-3 mm (clinically acceptable)

• Extends from the free gingival groove to the mucogingival junction
• Firmly attached to the underlying periosteum of alveolar bone
• Width varies: 3.5-4.5 mm (maxillary anterior), 3.3-3.9 mm (mandibular anterior)
• Narrowest over mandibular premolars
• Shows stippling (orange-peel appearance) - a sign of health
• Stippling is produced by interlacing of collagen bundles

• Fills the embrasure space between two adjacent teeth
• Anterior teeth: pyramid-shaped
• Posterior teeth: col-shaped (valley-shaped depression connecting facial and lingual papillae)
• Col is lined by non-keratinized epithelium - most susceptible to periodontal disease initiation

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MICROSCOPIC FEATURES

1. Stratum basale (germinativum) - cuboidal cells, mitotically active
2. Stratum spinosum - polyhedral cells with desmosomes
3. Stratum granulosum - contains keratohyalin granules
4. Stratum corneum - flat, anucleate (keratinized) OR stratum corneum with nuclei (parakeratinized)

• 3-4 cells thick at apex, 15-30 cells thick at base
• Attached to tooth by hemidesmosomes + internal basal lamina
• Attached to gingival connective tissue by external basal lamina
• Permeable due to wide intercellular spaces - acts as defense but also pathway for bacteria
• Rapid turnover (4-6 days vs. 6-12 days for oral epithelium)

• Papillary layer - projects into epithelial rete pegs; loose connective tissue
• Reticular layer - dense connective tissue adjacent to periosteum

• Collagen fibers: 60% (Type I predominantly)
• Fibroblasts: 65% of cells (most common cell type)
• Other cells: mast cells, macrophages, plasma cells, neutrophils
• Ground substance, blood vessels, nerves, lymphatics

1. Dentogingival fibers - most numerous; tooth to free gingiva
2. Alveologingival fibers - alveolar crest to gingiva
3. Circular/Circumferential fibers - encircle the tooth
4. Dentoperiosteal fibers - tooth to periosteum
5. Transseptal fibers - CEJ to CEJ of adjacent teeth (reconstructed after bone loss - important!)
6. Semicircular fibers - encircle tooth and insert into interdental papilla
7. Transgingival fibers - extend across interdental area

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Q2 (5 Marks) - Principal Fibres of Periodontal Ligament

• Fibers are not straight but wavy (crimp) - allows slight physiological tooth movement
• Intermediate plexus: Zone in middle third of PDL where fibers from bone and cementum overlap - allows remodeling
• Cells: Fibroblasts (most common), osteoblasts, cementoblasts, osteoclasts, undifferentiated mesenchymal cells, Malassez epithelial rests
• Blood supply: Superior/inferior alveolar arteries
• Innervation: Ruffini endings (mechanoreceptors), Krause end-bulbs, free nerve endings

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Q3 (5 Marks) - Plaque Formation and Maturation

Stages of Plaque Formation:

• Acquired pellicle forms within minutes of tooth cleaning
• Derived from selective adsorption of salivary glycoproteins, albumin, immunoglobulins onto the tooth surface
• Acellular, bacteria-free
• Acts as primer for bacterial adhesion

• Pioneer colonizers (primary colonizers) adhere to pellicle
• Predominantly Gram-positive cocci - mainly Streptococcus sanguis, S. mutans, S. salivarius
• Adhesion via specific receptor-ligand interactions (lectin-like adhesins to pellicle receptors)
• Reversible adhesion initially, then becomes irreversible

• Secondary colonizers attach to primary colonizers via co-aggregation (inter-bacterial adhesion)
• Gram-positive rods appear: Actinomyces species
• Corncob formations: Streptococci adhering around Actinomyces (seen microscopically)
• Plaque grows both by cell division and new bacterial adhesion

• Increasing diversity; Gram-negative rods and anaerobes appear
• Spirochetes and motile organisms appear
• Test-tube brush formations, bristle brush formations appear
• Fusobacterium nucleatum acts as a "bridge organism" connecting early and late colonizers
• Mature plaque has complex architecture with water channels (like vascular system)

• Complex community of Gram-negative anaerobes (Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia - "Red complex" of Socransky)
• Extracellular polysaccharides (glucans, fructans) form the matrix
• Quorum sensing regulates gene expression

• Supragingival: dominated by facultative Gram-positive organisms
• Subgingival: dominated by obligate Gram-negative anaerobes

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Q4 (5 Marks) - ANUG (Acute Necrotizing Ulcerative Gingivitis)

Definition:

1. Interdental papilla necrosis (punched-out papillae)
2. Pain
3. Bleeding

Etiology - Fusospirochetal Complex (Plaut-Vincent organisms):

• Fusobacterium nucleatum
• Treponema vincentii (Borrelia vincentii)
• Treponema denticola
• Prevotella intermedia

Predisposing Factors:

• Pre-existing gingivitis
• Smoking (most important local factor)
• Emotional stress / psychological stress
• Malnutrition, especially Vitamin C deficiency
• Immunosuppression - HIV/AIDS
• Poor oral hygiene
• Sleep deprivation

Clinical Features:

• Necrosis and ulceration of interdental papilla - begins at tip, spreads laterally
• Spontaneous gingival bleeding
• Pain/tenderness (distinguishes from chronic periodontitis)
• Fetid odor (fetor ex ore) - characteristic
• Gray pseudomembrane (slough) covering the ulcers
• Excessive salivation

• Fever, malaise, lymphadenopathy (submandibular)
• Leukocytosis

Histopathology:

1. Bacterial zone (superficial) - densely packed bacteria
2. Neutrophil-rich zone - PMNs and bacteria
3. Necrotic zone - necrotic tissue, spirochetes
4. Spirochetal infiltration zone - spirochetes penetrate vital tissue (deepest)

Diagnosis: Clinical (no specific lab test)

• Smear may show fusospirochetal complex
• Biopsy not usually required

Treatment:

• Debridement with cotton pellets soaked in H2O2 (3%)
• Gentle ultrasonic scaling
• Irrigation with warm water

• Metronidazole 400 mg TDS x 5 days (drug of choice)
• Amoxicillin as alternative
• Analgesics

• Warm saline rinses
• Chlorhexidine 0.2% mouthwash
• Rest, nutritional support
• Stop smoking

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Q5 (5 Marks) - GCF (Gingival Crevicular Fluid) and Its Functions

Definition:

Collection Methods (Brill & Krasse, 1958 - first described):

• Filter paper strips (most common)
• Micropipettes/capillary tubes
• Intracrevicular washings

Composition:

• Proteins: albumin, fibrinogen, fibronectin, complement components (C3, C4)
• Immunoglobulins: IgG, IgA, IgM
• Enzymes: alkaline phosphatase, aspartate transaminase (AST), beta-glucuronidase, elastase, MMP-8 (collagenase) Cellular Components:
• Neutrophils (most abundant cells - 95%)
• Lymphocytes, monocytes
• Desquamated epithelial cells

• Prostaglandins (PGE2 - marker of inflammation)
• Cytokines: IL-1β, IL-6, TNF-α

Functions of GCF:

1. Defense Function (most important):
   • Flushes bacteria and their products out of the sulcus (flow increases in inflammation)
   • Delivers PMNs, immunoglobulins, and complement into the sulcus
   • Antimicrobial proteins (lysozyme, lactoferrin) kill bacteria
2. Attachment of Junctional Epithelium:
   • Plasma proteins in GCF help in adhesion of JE to tooth surface (via fibronectin)
3. Washing/Cleansing Action:
   • Washes the sulcus, removes debris and bacteria
4. Diagnostic Marker:
   • GCF volume increases with inflammation (measured by Periotron)
   • Specific enzymes (MMP-8, AST) and cytokines (IL-1β, PGE2) are markers of periodontal disease activity
5. Nutritive Function:
   • Provides nutrients to junctional epithelium and subgingival flora

Clinical Significance:

• In health: GCF is minimal (transudate) - some authors say absent in perfect health
• In gingivitis/periodontitis: GCF volume markedly increases (exudate)
• GCF flow rate used to monitor treatment response

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Q6 (5 Marks) - Drug-Induced Gingival Enlargement

Three Main Drug Groups Causing DIGO:

Pathogenesis:

• Drugs or metabolites accumulate in gingival fibroblasts
• Inhibit collagen phagocytosis by fibroblasts (reduced collagenase activity)
• Increased fibroblast proliferation and collagen synthesis
• Net result: excess collagen accumulation = enlargement
• Cyclosporine also stimulates keratinocyte growth factor (KGF)
• Plaque and inflammation act as co-factors (worsen the condition)

Clinical Features:

• Begins in interdental papilla (first affected) - nodular enlargement
• Spreads to marginal gingiva
• May cover occlusal surfaces of teeth (severe cases)
• Firm, pink, non-hemorrhagic in drug effect alone
• Becomes red, soft, hemorrhagic with superimposed inflammation
• Painless unless secondarily infected
• Most pronounced on labial aspect of anterior teeth

Grading (Bokenkamp Classification):

• Grade 0: No signs of gingival overgrowth
• Grade I: Enlargement confined to interdental papilla
• Grade II: Enlargement involves papilla and marginal gingiva
• Grade III: Enlargement covers 3/4 or more of crown

Treatment:

1. Drug substitution (if possible) - Phenytoin → other AEDs; Nifedipine → Amlodipine (though amlodipine also causes DIGO); Cyclosporine → Tacrolimus
2. Thorough plaque control and oral hygiene instruction
3. Professional scaling and root planing
4. Surgical: Gingivectomy (for fibrotic enlargement) or periodontal flap surgery
5. If recurrence is a concern - continued plaque control critical

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Q7 (2 Marks) - Smoking and Periodontal Disease

Effects of Smoking on Periodontium:

• Reduced chemotaxis, phagocytosis, and oxidative burst
• Impaired PMN function leads to reduced host defense against periodontal pathogens

• Promotes colonization of Gram-negative anaerobes (P. gingivalis, T. denticola, T. forsythia - red complex)
• Higher levels of periodontal pathogens in smokers

• Nicotine reduces fibroblast attachment and proliferation
• Impairs healing and regeneration

• Reduced salivary and GCF IgA levels
• Altered cytokine profile - increased IL-1β, TNF-α
• Reduced GCF volume (due to vasoconstriction)

Clinical Consequences:

• Greater attachment loss and bone loss
• Deeper pockets
• More furcation involvement
• Palatal and posterior areas more affected in smokers
• Nicotine staining and calculus formation increased
• Poor response to periodontal therapy
• Impaired wound healing post-surgery
• Higher implant failure rates

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SHORT NOTES (2 Marks Each)

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1. Biological Width

• Defined by Gargiulo et al. (1961) based on cadaver studies
• Represents the physiological dimension of the dentogingival junction (the combined height of junctional epithelium + connective tissue attachment)

• Restorative margins must NOT encroach on biological width
• Violation causes chronic inflammation, bone loss, pocket formation
• Minimum 3 mm of healthy tissue required from alveolar crest to margin (1 mm sulcus + 2 mm biological width)
• Crown lengthening surgery is performed to re-establish biological width before placing subgingival restorations

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2. Chlorhexidine

• Bisbiguanide antiseptic; gold standard antiplaque agent in dentistry
• Available as: 0.2% mouthwash (UK), 0.12% mouthwash (USA), 0.2% gel, 1% subgingival gel

• Cationic molecule binds to negatively charged bacterial cell walls
• Disrupts cell membrane integrity → bacterial cell death
• Bacteriostatic at low concentrations, bactericidal at high concentrations
• Broad-spectrum: active against Gram-positive, Gram-negative bacteria, fungi (Candida), some viruses

• Binds to oral mucosa, salivary proteins, pellicle
• Releases slowly over 8-12 hours
• This property makes it superior to other antiseptics

• Post-surgical rinse
• Initial therapy adjunct
• Subgingival irrigation
• Implant maintenance
• ANUG management

• Brown staining of teeth and tongue
• Altered taste sensation (dysgeusia)
• Desquamation of oral mucosa
• Parotid gland swelling (rare)
• Does NOT have systemic toxicity

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3. Bone Sounding / Trans-Gingival Probing

• Local anesthesia administered
• A periodontal probe is inserted through the gingival tissue (trans-gingivally) until it contacts the alveolar bone
• Multiple readings taken around each tooth
• Bone topography is mapped to determine bone loss pattern

• Assess alveolar bone level (crest) before crown lengthening surgery
• Determine biological width violations
• Pre-surgical planning - identifies whether crown lengthening needed
• More accurate than radiographic bone level assessment
• Distinguish between thick and thin periodontal biotypes
• Assess furcation involvement

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4. Modified Bass Technique

1. Place toothbrush at 45-degree angle to the long axis of the tooth, directed toward the gingival sulcus
2. Bristles point apically (toward the gingival sulcus) - partially in sulcus, partially on gingival margin
3. Apply light pressure and perform short horizontal vibratory strokes (10 strokes per area) without moving the brush from the sulcus - this is the Bass component
4. Then roll the brush occlusally (toward the crown) with a sweeping motion to remove dislodged plaque - this is the "modified" component
5. Repeat for all areas; use 2-3 teeth per section, systematic approach

• Most widely recommended for adults
• Patients with periodontal disease / plaque-induced gingivitis
• Patients with recession or exposed root surfaces
• Adult patients with tendency for subgingival plaque accumulation

• Most effective for cleaning the gingival sulcus
• Removes subgingival plaque
• Good for patients prone to periodontal disease

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5. Non-Specific Plaque Hypothesis

• Periodontal disease is caused by the overall mass/quantity of plaque, not by specific bacteria
• All bacteria in plaque are equally pathogenic
• The larger the total plaque mass → the greater the toxin/metabolic by-product load → the more tissue destruction
• Individual organisms are not specifically responsible

• Experimental gingivitis studies (Loe et al., 1965) showed that withholding oral hygiene from periodontally healthy individuals produced gingivitis in all subjects regardless of specific bacteria
• Gingivitis resolved with plaque removal in all cases

• Non-specific plaque removal (scaling, plaque control, oral hygiene) should resolve disease
• No need to target specific bacteria

• Cannot explain why some plaque-harboring patients don't get disease
• Cannot explain site-specificity of disease
• Discovery of specific pathogens (P. gingivalis, A. actinomycetemcomitans) challenged the non-specific concept

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