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Paper A RevisionUpdated 202610 min read

Operative & Restorative Dentistry for ORE Part 1

Essential review of composite resins, dental amalgam, glass ionomer cements, bonding agents, and SDCEP caries guidelines.

Key Syllabus Concepts Tested in Operative & Restorative Dentistry

  • Composite resin fillers (Barium/Strontium radiopacity) and C-factor polymerization shrinkage stress
  • Dental amalgam phases: High-copper amalgams eliminating corrosion-prone Gamma-2 (Sn8Hg) phase
  • 10-MDP universal adhesive monomer chemical bonding to hydroxyapatite and zirconia
  • SDCEP selective caries removal guidelines preserving pulpal vitality in asymptomatic teeth

Sample SBA Practice Questions

Sample Question 1 (Paper A)

In adhesive dentin bonding, the hybrid layer is formed by the penetration of resin monomers into which acid-etched dentinal structure?

  1. Hypermineralised peritubular dentine cuff
  2. Resin-tag-filled dentinal tubule lumens
  3. Partially dissolved smear layer debris
  4. Demineralised intertubular collagen fibre network

Correct Answer: Demineralised intertubular collagen fibre network
Explanation: Phosphoric acid etching demineralizes intertubular dentin and exposes a delicate network of type I collagen fibers forming the hybrid layer.
Clinical Pearl: Parotid gland is purely serous, producing alpha-amylase rich saliva.

Sample Question 2 (Paper A)

Which cavity preparation feature provides resistance form against displacement of an amalgam restoration under occlusal forces?

  1. Buccal and lingual walls converging towards the occlusal surface
  2. Retention grooves cut into the proximal box line angles
  3. Flat pulpal floor cut perpendicular to the occlusal forces
  4. Dovetail extension of the occlusal outline form

Correct Answer: Flat pulpal floor cut perpendicular to the occlusal forces
Explanation: A flat pulpal floor perpendicular to masticatory forces prevents tipping and wedging forces.
Clinical Pearl: Fluorapatite lowers enamel critical pH for demineralization from 5.5 down to 4.5.

Sample Question 3 (Paper A)

What is the principal component of glass ionomer cements (GIC) responsible for chemical adhesion to hydroxyapatite?

  1. (+)-Tartaric acid, the setting reaction modifier
  2. Polyacrylic acid, the ionisable polymer in the liquid
  3. Fluoroaluminosilicate glass, the ion-leachable powder
  4. 2-hydroxyethyl methacrylate, the hydrophilic resin monomer

Correct Answer: Polyacrylic acid, the ionisable polymer in the liquid
Explanation: Polyacrylic acid carboxyl groups form ionic chelation bonds with calcium ions in enamel and dentin hydroxyapatite.
Clinical Pearl: Carbonic acid/bicarbonate (HCO3-) is the primary buffer system in stimulated saliva.

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