Quiz #1: Principles of Crown Preparations Flashcards
1
Q
Why demand such extreme detail when preparing teeth?
A
- irreversible
- patients demand thoughtful precision
- careful preparation = future health of tooth
2
Q
When do you plan for a crown?
A
- gross caries
- fracture
- trauma
- wear
- large existing restoration
3
Q
What are the 7 key principles of crown preparation?
A
- Conservation of tooth structure
- Retention form
- Resistance form
- Structural durability
- Marginal integrity
- Preservation of the periodontium
- Aesthetics
4
Q
A
5
Q
What is conservation of tooth structure?
A
- removes enough tooth for material strength and optimal contours
- remove all caries and decay
- stay above gingiva
- avoid vital pulp tissue
6
Q
What is retention form?
A
- quality of prep that prevents the restoration from becoming dislodged by forced parallel to path of placement
- usually fracture and caries cause failure of crowns rather than lack of retention
7
Q
Retention relies on what 5 things?
A
- stickiness of food (dislodging force)
- roughness of fitting surface
- materials being cemented
- film thickens and properties of luting agents
- geometry of tooth prep
8
Q
What is the geometry of the prep?
A
- cylindrical/tapered
- proper taper for retention
- tapered axial walls should converge
- may have seating issues with temporary/final restoration
9
Q
What is undercut?
A
irregularities in wall of prepped tooth that prevents withdrawal or seating of crown
10
Q
What is undercut?
A
irregularities in wall of prepped tooth that prevents withdrawal or seating of crown
11
Q
What is the purpose of the resistance form?
A
- prevent dislodgment in horizontal forces
12
Q
What happens when you have too much taper?
A
Convergence
retention will decrease
13
Q
What determines the structural durability of a crown?
A
- reduced adequately
- proper anatomical contours
- material choice
14
Q
What is the diameter of the 878k-16 bur?
A
1 mm diameter
15
Q
What is the diameter of the 878k-16 bur?
A
1 mm diameter
