Class I & V Preparation Fundamentals Flashcards
Principles of tooth preparation for amalgam restorations include: (3)
- Visibility
- Access
- Moisture control
When doing an amalgam restoration, have a means for _____ of the site
Isolation
Modes of isolation include:
- Rubber dam (gold standard)
- Cotton rolls
- Retraction cord
- Isovac
Principles: Treatment of tooth structure-
All _____ must be removed from all margins
Undermined enamel
Enamel that is not supported by dentin underneath it:
Undermined enamel
_____ must support all surface enamel:
Dentin
Margins should be ____ at the cavosurface of all axial surfaves:
90 degrees
On the occlusal surface, margins may be _____ in some areas, but must NEVER BE ____ anywhere on the tooth
Slightly obtuse; Acute
What would occur if the margins of the cavosurface were acute?
Enamel would break
Ideal preparations are _____ to _____ into the dentin
0.2mm to 0.5mm
Ideal preparations must be prepared through the:
ENTIRE enamel layer
In a live patient the depth of an ideal preparation into the dentin is determined by:
Caries
The tradition teaching about the outline form of an amalgam preparation states that the preparation must NOT terminate in:
The bottom of a FISSURED pit or groove
On class II amalgams, contact is broken:
Facially & lingually
Preparations should encompass all carious & badly demineralized areas, this is called:
Extension for prevention
Term that refers to what holds a restoration in a tooth:
Retention form
Does amalgam bond to tooth structure?
no
Smaller amalgams are held in by ______ and/or ______ if no walls can converge
Convering walls; Retention grooves
Elements in the design of a tooth preparation that will help both restoration & tooth resist fracturing:
Resistance form
Maintaining as much tooth structure as possible makes the tooth:
Less likely to fracture
Having some areas on the floor of a multi-surface preparation that are _____ to the ____ make the restoration less likely to fracture
Perpendicular; occlusal forces
______ the internal line angles on a preparation (at least a little bit) make the tooth less likely to fracture
Rounding
Smoothly rounding the outline form makes the ____ less likely to fracture
Restoration
Preparing to _______ prevents weakness (resists fracture) in the restoration
Proper depth
Never leave ____ on the floor of a preparation
Enamel
Never leave a _____ on an enamel wall of an occlusal preparation, like a class I amalgam
Partial-depth ledge
Avoid leaving ____ under an amalgam that is subject to occlusal stress
Sharp external line angles
A buccal pit amalgam preparation can be classified as a:
Class I
A class I buccal pit amalgam occurs in the ______ tooth
Occlusal 2/3 of molar
A class I buccal pit amalgam restores a:
Developmental pit
Despite being on the axial surface, a buccal pit amalgam is NOT a:
Class V
For a buccal pit preparation, use the ____ bur. Its flutes are ____ top-to-bottom, so they area gauge for proper depth.
330; 1.5mm
The 330 bur is a ______ shape, so it will naturally ______
Inverted cone; converge walls
Describe whether the following should be converging or diverging:
- Buccal walls in isthmus area:
- Lingual walls in isthmus area:
- Distal wall:
- Lingual wall at lingual groove:
- Mesial wall:
- Wall at buccal groove:
- Converging
- Converging
- Diverging
- Diverging
- Diverging
- Diverging
Walls at the terminal ends of buccal & lingual groove should diverge ____ degrees
3 degrees
Walls in the isthmus area converge ____ degrees on each side of the preparation, & isthmus width is ____ minimum
3; 1mm
Walls adjacent to marginal ridges ____ by ___ degrees
Diverge; 3 degrees
Diverging the mesial or distal wall adjacent to the marginal ridge leaves ______ for the ridge in this area
Dentin support
Occlusal amalgam depth:
0.2mm inside the DEJ
Converging the wall adjacent to the marginal ridge risks _____ for the marginal ridge
Risks destruction of the dentin support
How can you avoid off-axis preparation?
Enter teeth parallel to the long axis of the crown, not the patien
Bur inclines more mesially in the ____ & more distally in the ____ the further posteriorly we go due to the ____-
mandible; maxilla; curve of spee
Bur inclines more lingually in the ____ and more buccally in the ____ the more posteriorly we go, due to the _____
mandible; maxilla; curve of wilson
If the preparation is still in the enamel it is:
Too shallow
Angular outline form could cause:
Areas of stress concentration
The 169 bur will give a slightly _______ prep since it is a _____ shaped bur
diverging; tapered fissure bur
The 169 bur flute measures _____ top-to-bottom
4 mm
Shape & depth of a 245 bur:
Inverted cone bur, with rounded edges on its flat end; 3mm
Restores caries on the gingival 3rd of the buccal and lingual surfaces of the teeth:
Class V preparation
Almost all caries starts _____ but often spreads ____ onto the root surface:
Supragingivally; subgingivally
In class V amalgam preparation, the axial wall is _____, and a _____ should be present
Convex; gingival retention groove
A gingival retention groove in a class V amalgam preparation is located:
In the dentin, just inside the DEJ
Enamel in the cervical is _____ compared to the occlusal area
thinner
In a class v preparation, since the prep is in a smooth area, the outline form is determined by ____
Extent of the caries (rather than following the anatomy)
In a class V amalgam preparation, since the prep is in a convex surface and all amalgam margins must be 90 degrees; all walls _____ & _____ are need for retention
Diverge; grooves
In a class V amalgam preparation, the axial wall is ____ when caries is minimal
Convex
When caries extend on the root surface/subgingival the rules for ____ may change
Depth
When caries extend onto the root surface/subgingival, the rules for depth may change:
A) when there is a minimum thickness of enamel:
B) When the margin is on the root:
A) 1mm depth
B) 0.75mm depth
Describe the placement of a retention groove in a class v buccal amalgam restoration:
What if is is in an extremely deep prep:
Entirely in dentin, just inside DEJ
The grooves still go just inside the DEJ
What is used to remove undermined enamel interproximally?
Gingival margin trimmer
