1/25: Class I and Class V Prep. Fundamentals Flashcards
Having a means for isolation of the site does what three things?
- Visibility
- Access
- Moisture control (especially when restoring composite resin)
What are 4 principles of isolation?
- Rubber dam (gold standard)
- Retraction cord
- Cotton rolls
- Isovac
All undermined enamel must be ________ from all margins
Removed
What is undermined enamel?
Enamel that is not supported by dentin under it
*Dentin MUST be supported by all surface enamel
Margins should be ______ degrees at the cavosurface on all axial surfaces
90*
On the occlusal surface, margins may be slightly _______ in some areas, but must NEVER be ________ anywhere on the tooth
obtuse; acute
*enamel would break
Ideal preparations are ______ to _______ into the dentin
0.2mm to 0.5mm
*must prepare through the ENTIRE enamel layer
*in a live patient, this is determined by caries
A prep of 0.2mm to 0.5mm into the dentin means that?
Different depths in different places on the tooth
*it will depend on the thickness of the enamel in the area
What does retention form mean?
Holds a restoration in a tooth (RETAINS the restoration)
Amalgam doesn’t bond to _______
Tooth structure
Smaller amalgams are held in by _____________ if no walls can converge
Converging walls and/or by retention grooves
What are elements in the design of a tooth preparation that will help both restoration and tooth resist fracturing?
Resistance form
What makes the tooth less likely to fracture?
- Maintaining as much tooth structure as possible
- Rounding internal line angle on a preparation (a little bit)
Preparing to PROPER DEPTH prevents ___________ in the restoration
Weakness (resists fractures)
- NEVER leave enamel on the floor of an amalgam preparation
- NEVER leave a partial-depth ledge on the enamel wall of an occlusal preparation like a class I amalgam
Avoid leaving _________ under an amalgam that is subject to occlusal stress
Sharp external line angles
- This could result in fracture of the RESTORATION
ex: axial wall of class II prep
What makes a restoration less likely to fracture?
- Having some areas on the floor of a multi-surface preparation that are perpendicular to occlusal forces
- Smoothly rounding outline forms
What classification is a buccal pit amalgam?
Class I
*NOT a class V desite being on axial surface
Where does a class I buccal pit amalgam occur?
2/3 of molar tooth
What does a class I buccal pit restoration restore?
Developmental pit
The walls at the terminal ends of the buccal and lingual grooves ______ _______ degrees
Diverge 3 degrees
Walls in the isthmus areas ___________ on each side of the preparation
Converge 3 degrees
Isthmus width is _______ minimum
1mm
Walls adjacent to marginal ridges ____________
Diverge 3 degrees
_________ the mesial or distal wall adjacent to the marginal ridge leaves _________ for the ridge in this area
Diverging; dentin support
