Intro To Cast Restorations and book info (Kerby) Flashcards
What are contraindications for a crown?
- esthetics
- less than max retention necessary
What are indications for a crown?
- extensive destruction from caries or trauma
- endo treated teeth
- correction of occlusal plane
- provide contours to receive a removable partial denture
What are advantages of a crown?
High strength and good retentive qualities
What is retention form?
Apical or oblique forces to a tooth
What are disadvantages of a crown?
- removal of a large amount of tooth structure
- adverse effects on tissue
- display of metal
- vitality testing not feasible
Whenever possible, where should the margin be placed?
Supragingival
What are advantages of supragingival margins?
- They can be easily finished without associated soft tissue damage
- They are more easily kept plaque free
- Impressions are more easily made
- Restorations cal be easily evaluated at the time of appointment
When is a subgingival margin justified?
- Dental caries, cervical erosion, or restorations extend subgingivally, and a crown lengthening procedure is not included
- The proximal contact area extends to gingival crest
- Additional retention and or resistance is needed
- The margin of a metal ceramic crown is to be hidden behind the labiogingival crest
- Root sensitivity can’t be controlled by more conservative procedures
- Modification of axial contour is indicated, such as to provide an undercut to provide retention.
Which hand piece situation creates the highest pulp temp?
Low speed and no water.
T or f: it’s ok to use the hand piece without water.
False. Water is needed so that the pulp does not over heat
What is the temp of critical pulp temp?
6-10 degree C increase
How many seconds does it take for a low speed with no water to reach pulp temp critical temp
About 20 seconds
What is the safe range for pulp temp?
-10 to 6 degrees C
T or f: retention becomes less as taper increases
True
T or f: a slight increase in axial wall taper significantly reduces retention?
True
