Operative Flashcards
What are the principles of cavity preparation?
Cavity preparation follows physical and mechanical principles based on tooth and restorative material properties. It begins with a conservative, ideal preparation, adjusted based on clinical needs.
What guides modifications in cavity preparation?
Critical thinking and clinical judgment guide modifications to adapt to each clinical situation.
What is the composition of enamel?
Enamel is 95-98% inorganic, making it brittle and prone to fractures along rods. It requires support from underlying dentin.
What is the composition of dentin?
Dentin is 75% inorganic, providing compressive strength and supporting enamel.
What are the requirements for amalgam in cavity preparation?
Amalgam requires a depth of 1.5–2.0 mm for strength, with 90-degree margins and undercuts for retention.
How does composite bond to tooth structure?
Composite bonds to enamel and dentin via micromechanical bonding using the acid-etch technique. Cavosurface margins can be butt-joint or beveled.
What are the initial stages of cavity preparation (Black’s Steps)?
- Outline Form and Initial Depth: Create external margins to remove decayed tissue. 2. Primary Resistance Form: Prevent fracture by ensuring correct depth, isthmus width, and removing unsupported enamel. 3. Primary Retention Form: Ensure retention with undercuts for amalgam and bonding for composite. 4. Convenience Form: Ensure adequate observation and access.
What are the final stages of cavity preparation (Black’s Steps)?
- Remove infected dentin or old restorative material. 2. Check for the need for pulp protection (liners for deep preparations). 3. Secondary retention (e.g., grooves, bevels). 4. Finish external walls (beveling or smoothing). 5. Clean, inspect, varnish, or condition the preparation.
What is the outline form in cavity design considerations?
Maintain sound tooth structure while removing decay. Amalgam requires an initial depth that penetrates 0.5 mm into dentin and a minimum isthmus width of 1 mm.
What is the primary resistance form in cavity design considerations?
Prevent fractures by avoiding sharp internal/external angles and recognizing and removing unsupported enamel at the cavosurface margins.
What is the primary retention form in cavity design considerations?
Mechanical undercuts are required for amalgam, while micromechanical retention for composite is achieved using bonding agents.
What is the convenience form in cavity design considerations?
Modify preparation to allow visibility and ease of instrument use.
What is the location for decay removal?
Remove decay from lateral walls and pulpal/axial walls last to avoid pulp exposure.
How can color and texture help in identifying decay?
Not all staining is decay. Infected dentin is soft and moist and must be removed, while affected dentin is leathery and dry and can remain and remineralize.
What is the purpose of pulp protection?
Bases provide thermal protection, while liners protect freshly cut dentin. Minimal use of bases is needed under composite since it doesn’t require thermal protection.
What are secondary resistance and retention forms?
Macro-mechanical forms include grooves, slots, pins, and boxes, while micromechanical forms involve acid etching for composite bonding.
What are the finishing requirements for external walls?
Amalgam requires butt joint margins (90° angle), while composite can use beveled or butt joint margins. Ceramic restorations require precise 90° margins.
What are the final procedures in cavity preparation?
Avoid desiccating the preparation, remove unsupported enamel unless using bonding materials, and apply varnishes and bonding agents to reduce leakage and sensitivity.
How does acid etching improve bonding strength?
Acid etch improves bonding strength for composite restorations.
