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Full Written Answer: Minimally Invasive Procedures and Concepts in Conservative Dentistry (25 Marks)

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1. DEFINITION (2 marks)

• Also called Minimal Intervention Dentistry (MI Dentistry)
• Proposed and popularized by the FDI World Dental Federation
• Core idea: Maximum preservation of healthy tooth structure

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2. CONCEPTS / PRINCIPLES OF MID (5 marks)

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3. CARIES DETECTION METHODS (3 marks)

• Laser fluorescence device (655 nm red laser)
• Detects subsurface caries by measuring fluorescence of bacterial porphyrins
• Gives numerical reading: 0-99 (>21 = cavitated caries)
• Non-invasive, no radiation

• Uses visible light passed through tooth
• High-contrast digital images show cracks, caries, fractures
• No radiation; real-time images

• Scores 0-6 based on visual-tactile examination
• Standardizes caries diagnosis and intervention thresholds

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4. MINIMALLY INVASIVE PROCEDURES (12 marks)

A. Atraumatic Restorative Treatment (ART) (2 marks)

• Uses hand instruments only (no rotary burs, no electricity)
• Caries removed with excavators; cavity restored with GIC (Glass Ionomer Cement)
• GIC releases fluoride - promotes remineralization
• Ideal for: field settings, developing countries, anxious/young patients
• Evidence base: WHO promotes ART globally

B. Pit and Fissure Sealants (1 mark)

• Resin or GIC applied to susceptible pits and fissures of posterior teeth
• Blocks bacterial colonization and nutrient supply
• Most effective when applied soon after tooth eruption
• Preventive, not restorative

C. Air Abrasion (1 mark)

• High-velocity stream of aluminium oxide particles through pressurized air
• Removes caries/stains via kinetic energy
• Advantages: no heat, no vibration, no noise, no anesthesia needed
• Preserves healthy tooth structure

D. Laser Dentistry (2 marks)

• Er:YAG laser and CO2 laser used for caries removal
• Precisely ablates carious tissue without damaging healthy dentine
• Bactericidal effect on residual bacteria
• Reduced need for anesthesia; promotes adhesive bonding
• Also used for: cavity preparation, caries prevention (laser fluoride)

E. Ozone Therapy (1 mark)

• Ozone gas (O3) applied to carious lesion
• Kills cariogenic bacteria (S. mutans) by oxidative damage
• Promotes remineralization of early lesions
• Non-invasive for initial/root caries

F. Chemomechanical Caries Removal - Carisolv (2 marks)

• Carisolv gel (NaOCl + amino acids) applied to carious dentine
• Selectively softens and dissolves infected (denatured collagen) dentine only
• Affected (remineralizable) dentine is preserved
• Removed with special hand instruments (no bur required)
• Advantages: painless, conservative, no anesthesia in most cases

G. Tunnel Preparation (1 mark)

• Access to proximal caries from the occlusal surface through a tunnel
• Preserves the marginal ridge - most important contact area
• Restored with GIC
• Indication: Class II proximal caries with intact marginal ridge

H. Slot Preparation (1 mark)

• Access to proximal lesion from facial or lingual surface
• Conservative alternative to traditional Class II box preparation
• Preserves more tooth structure than conventional cavity

I. Ultrasonic/Sonic Preparation (1 mark)

• Oscillating tips remove caries with minimal vibration
• More conservative than conventional burs
• Useful in tight proximal areas

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5. CAVITY DESIGN PRINCIPLES IN MID (2 marks)

• Adhesive dentistry has replaced mechanical retention as the foundation
• Composites and GIC bond to tooth - no need for undercuts

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6. SUMMARY DIAGRAM

MINIMALLY INVASIVE DENTISTRY
           |
    ┌──────┼──────────────┐
    |             |              |
 DETECT       PREVENT         TREAT
(ICDAS,     (Fluoride,     (ART, Laser,
DIAGNOdent, Sealants,     Carisolv,
DIFOTI)     CRA)          Air Abrasion,
                          Ozone, Tunnel)

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KEY TAKEAWAY

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• Definition: 2 marks
• Principles/Concepts: 5 marks
• Detection methods: 3 marks
• Procedures (8-9 procedures): 12 marks
• Cavity design comparison: 2 marks
• Diagram/presentation: 1 mark

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EXTENDED ANSWER: Minimally Invasive Dentistry - Additional Topics

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5. SILVER DIAMINE FLUORIDE (SDF)

• Composition: 38% aqueous solution of silver diamine fluoride
• Mechanism:
  • Silver ions: bactericidal - kills S. mutans and other cariogenic bacteria
  • Fluoride ions: promotes remineralization of softened enamel/dentine
  • Together: arrests active caries lesions
• Clinical procedure: Apply with microbrush to carious lesion; no drilling
• Efficacy: 80-90% caries arrest rate in primary teeth (clinical trials)
• Limitation: Stains arrested caries permanently black (cosmetic concern)
• Uses: Elderly, anxious patients, pre-cooperative children, patients with special healthcare needs (SHCN)
• Classification: Non-operative (no cavity preparation required)

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6. RESIN INFILTRATION (ICON - DMG, Hamburg)

• Classification: Micro-invasive procedure
• Indication: White spot lesions (initial enamel caries, ICDAS 1-2), non-cavitated proximal caries
• Mechanism: Fills enamel micropores with low-viscosity resin; halts progression by blocking acid diffusion pathways
• Step-by-step protocol:
  1. Etch with 15% HCl gel (Icon-Etch) for 2 min - opens enamel pores
  2. Dry with ethanol (Icon-Dry) - removes moisture, shows final optical result
  3. Infiltrate with low-viscosity resin (Icon-Infiltrant) - fills pores
  4. Light cure 40 sec
• Advantages: No drilling, no anaesthesia, prevents lesion from becoming cavitated, improves aesthetics (white spot disappears)
• Limitations: Only for non-cavitated lesions; not for active cavities

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7. HALL TECHNIQUE (Stainless Steel Crown - Modified)

• Concept: Sealing caries rather than excavating it
• Procedure: Stainless Steel Crown (SSC) cemented over carious primary molar with GIC - no caries removal, no tooth preparation, no drilling
• Principle: Sealing bacteria from their carbohydrate substrate arrests the lesion (bacteria starve and become inactive)
• Evidence: 5 RCTs show clinical success equivalent to conventional SSC placement
• Best for: Primary molars in children, anxious/pre-cooperative patients
• Originator: Dr. Norna Hall, Scotland, 1990s

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8. STEPWISE EXCAVATION

• Indication: Deep caries approaching pulp where complete removal risks pulp exposure
• Aim: Avoid unnecessary pulp exposure while removing infected caries
• Two-visit technique:

• Why it works: Sealing caries stimulates odontoblasts to lay down tertiary/reactionary dentine, increasing pulp-to-caries distance
• Modern alternative: Single-visit partial caries removal (selective caries removal to firm dentine) - ICCMS guidelines

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9. SELECTIVE CARIES REMOVAL (ICCMS Guidelines - 2019)

• Replaces the old concept of "complete caries removal"
• Based on dentine hardness and proximity to pulp:

• Selective to firm dentine: For shallow-moderate lesions
• Selective to soft dentine: For deep lesions near pulp (then seal)
• Reduces pulp exposure risk significantly

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10. SONOABRASION

• Uses ultrasonic oscillating tips (not rotating burs) to remove caries
• Produces less heat, vibration, and noise than conventional drilling
• Tips are shaped like inverted cones or chisel tips
• Useful for tight proximal areas and tunnel preparations
• More conservative than rotary instruments

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11. PAPACARIE (Enzymatic Caries Removal)

• Active agent: Papain enzyme (from papaya) + Chloramine + Toluidine blue
• Mechanism: Papain selectively digests denatured (infected) collagen in carious dentine; does NOT affect intact (sound) collagen
• Procedure: Apply gel, wait 30-60 sec, remove softened dentine with blunt excavator; repeat
• Advantages: Selective, painless, no drilling, low cost, no anesthesia needed
• Limitations: Multiple applications needed; less effective for enamel caries

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12. PREVENTIVE RESIN RESTORATION (PRR)

• Introduced by Simonsen (1978) - one of earliest MID techniques
• Indication: Pit and fissure caries with minimal enamel involvement
• Technique:
  1. Air abrasion or small bur removes minimal carious enamel
  2. Composite resin placed only in the carious portion
  3. Remaining pits and fissures sealed with sealant
• Types: Type A (sealant only), Type B (small composite + sealant), Type C (larger composite + sealant)
• Maximally preserves tooth structure while treating and preventing caries

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13. GLASS IONOMER CEMENT (GIC) IN MID

• RMGIC (Resin-Modified GIC): Improved aesthetics and strength; used in ART
• High-viscosity GIC: Stronger; used in ART for posterior teeth (Fuji IX, Ketac Molar)

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14. REMINERALIZING AGENTS

a) Fluoride (multiple delivery systems)

• Fluoride varnish (5% NaF): 22,600 ppm F; applied every 3-6 months
• Fluoride toothpaste: 1000-1450 ppm F daily use
• Mechanism: Fluorapatite formation - more acid resistant than hydroxyapatite

b) CPP-ACP (Casein Phosphopeptide - Amorphous Calcium Phosphate)

• Trade name: Recaldent (in GC Tooth Mousse)
• CPP acts as a carrier that stabilizes ACP at the tooth surface
• ACP provides Ca2+ and PO4³- for remineralization
• Effective for white spot lesions, root caries, post-orthodontic demineralization

c) Self-Assembling Peptides (P11-4 / Curodont)

• Synthetic peptide matrix that assembles into scaffold at caries site
• Attracts calcium and phosphate - biomimetic enamel regeneration
• Applied non-invasively; promotes remineralization of ICDAS 1-2 lesions

d) Bioactive Glass (Novamin - SrSiO2 + CaO + Na2O + P2O5)

• Releases calcium, sodium, phosphate when in contact with water
• Forms hydroxyapatite layer on tooth surface
• Used in toothpastes (Sensodyne Repair & Protect)

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15. CARIES RISK ASSESSMENT (CRA) - CAMBRA PROTOCOL

• Low risk: Preventive measures + annual recall
• Moderate risk: Fluoride varnish + dietary advice + 6-monthly recall
• High risk: SDF + ART + intensive fluoride + 3-monthly recall

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16. HISTORICAL TIMELINE OF MID

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17. COMPARISON TABLE: Conventional vs. Minimally Invasive Approach

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18. ADHESIVE DENTISTRY - Foundation of MID

• Modern MID relies entirely on adhesive (bonded) restorations
• Composites and GICs bond chemically/micromechanically to enamel and dentine
• No need for mechanical retention (no undercuts, no resistance/retention form)
• This allows very small, conservative cavity designs
• Total-etch, self-etch, and universal adhesives used based on substrate

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EXAMINER'S TIPS - How to score full 25 marks:

1. Definition - must include FDI's definition (2 marks)
2. Principles - ICDAS, remineralization, CRA, repair vs replace (4 marks)
3. Procedures - min. 6-8 procedures with mechanisms + diagrams (12 marks)
4. Biomaterials - GIC, CPP-ACP, SDF, ICON (4 marks)
5. Comparison table - conventional vs MID (2 marks)
6. Neat presentation - diagrams, labels, arrows (1 mark)