Class I & V Preparation Fundamentals Flashcards
Principles of tooth preparation for amalgam restorations include:
- 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 on all axial surfaces
90 degrees
On the occlusal surface, margins may be ____ in some areas but must NEVER BE ____ anywhere on the tooth
slightly obtuse; never be acute
What would occur if the margins at the cavosurface were acute?
enamel would break
Ideal preparations are ____ to ____ into the dentin:
0.2mm-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 traditional 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 and lingually
Preparations should encompass all carious and 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 heading by ____ and/or _____ if no walls can converge
converging walls and/or retention grooves
Elements in the design of a tooth preparation that will help both restoration and tooth resist fracturing:
resistance form
Retaining as much tooth structure as possible makes the 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
_____ internal line angles on a preparation (at least a little bit) make the tooth less likely to fracture
rounding
Smoothing 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 the 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 can be classified as:
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 axial surface, a buccal pit amalgam is NOT a:
class V
For a buccal pit preparation, use the ____ bur. It flutes are _____ top-to-bottom so they are a gauge for the proper depth
330; 1.5mm
The 330 bur is a ____ shape so it 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 of lingual groove:
- mesial wall:
- Wall at buccal groove:
- converging
- converging
- diverging
- diverging
- diverging
- diverging
Walls at the terminal ends of the buccal and lingual grooves should diverge ____ degrees
3
Walls in the isthmus areas converge ___ degrees on each side of the preparation, isthmus width is ___ minimum
3 degrees; 1 mm
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:
.3 mm inside the DEJ
Converging the wall adjacent to the marginal ridge risks ____ for the marginal ridge
destruction of the dentin support
How can you avoid an off-axis preparation?
Enter teeth parallel to the long axis of the crown, not the patient
Bur inclines more medially in the ____ and more distal in the ___ the further posterior we go, do to the ___
mandible; maxilla; curve of Spee
Bur inclines more lingually in the ____ and more bucally 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
The #169 bur flute measures ____ top to bottom
4mm
Shape and depth of 245 bur:
inverted cone w/ rounded edges on its flat end; 3mm
Restores caries on the gingival 3rd of the buccal and lingual surfaces of teeth
Class V preparation
Almost all caries start ___, but often spreads ___ onto the root surface
supragingivally; subgingivally
In a 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 on the cervical area is ____ compared to the occlusal area
thinner
In class V preparation, since the prep is in a smooth area, the outline form is determined by:
extent of caries (rather than following anatomy)
In a class V amalgam prep, since the prep is in a convex surface and all amalgam margins must be 90 degree; all walls ____ and ____ are needed for retention.
diverge; grooves
In a class V amalgam prep, the axial wall is ___ when caries is minimal
convex
When caries extend on to the root surface/subgingival, the rules for ____ may change
depth
When caries extend on to the root surface/subgingival the rules for depth may change:
A- When there is a minimum thickness of enamel:
B- When 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 prep:
What if its an extremely deep prep?
Entirely in dentin just inside DEJ
the groove still go just inside the DEJ
What is used to remove undermined enamel inter proximally?
gingival margin trimmer
