38. Primary phases of cavity preparation, definition of each phases

Question 1

Primary phase of cavity preparation
1. What are the 3 steps of primary phase of cavity preparation?

Answer 1

1/ Opening of the cavity
2/ Making outline form with initial depth
3/ Primary retention and resistance form are prepared together

Question 2

Primary phase of cavity preparation
2. How does step 2: outline form, initial depth occur?

Answer 2

Outline form and initial depth are prepared together, high speed, watercooling, diamond burs

Question 3

Primary phase of cavity preparation
3. Characteristics of primary retention form?

Answer 3

1/ Preparation resists displacement or removal of the restoration from tipping or lifting forces

2/ Retention is influenced by the contact between the restorative material and tooth
- mechanical contact:
+) macromechanical: amalgam
+) micromechanical: composite
- chemical: rare, glassionomer
- electrical: weak

Question 4

Primary phase of cavity preparation
4. Characteristics of primary resistance form ~ convinience form?

Answer 4

• Both the tooth and restoration can withstand the masticatory forces without fracture
• Primary retention and resistance form are prepared together
• Principles: box shape, flat floor, slightly rounded line angles, thickness of restorative material, walls: parallel, divergent or convergent

Question 5

Primary phase of cavity preparation
5. What are principles of primary resistance form ~ convenience form?

Answer 5

1/ box shape, flat floor, slightly rounded line angles, thickness of restorative material
2/ walls: parallel, divergent or convergent