6. Class II Amalgam Preparation Flashcards
Class II Lesion
Found on the ____ surfaces of ____ teeth (sides of teeth)
____ surface cavity
Found mesially and distally usually just below the ____
(where the teeth touch each other)
proximal
posterior
smooth
contact points
Classification by Surface \_\_\_\_ surface Take the name of both surfaces Examples Mesio-occlusal (MO) Disto-occlusal (DO)
Classification by Complexity
____
Prepared cavities
that involve ____ tooth surfaces
two
compound
two
Begins with a broad decalcification of enamel
See a ____ of decay progressing through enamel towards dentin on an x-ray
At DEJ, decay spreads out then forms a ____ of decay towards the pulp
Cones of decay are ____ to ____ at DEJ
Once the lesion reaches dentin, it flares at the DEJ
Proximal surface is still intact
Only see lesion on an ____
Eventually the surface breaks down and explorer can penetrate
Then, the lesion progresses toward pulp
cone cone apex base x-ray
Clinical appearance
May not have a clincal appearance, or
____ over the marginal ridge if the cavity has progressed and undermined the enamel
opacity
Noncavitated: \_\_\_\_ intact \_\_\_\_ of proximal surface may be present Superficial radiolucency may be present Marginal ridge is not \_\_\_\_
■ Cavitated: Surface broken, detected visually or possibly tactilely Marginal ridge may be discolored /shadow \_\_\_\_ area in dentin on transillumination Radiolucency is present beyond the \_\_\_\_
surface opacity discolored opaque DEJ
Class II Preparation
Considerations:
An extension of Class I
Occlusal surface is normally included Convenience form
Extension for prevention
Lesion is removed by creating a box shaped preparation around the caries
Anatomic Considerations: Some areas are not included in the preparation:
Intact ____ on maxillary molars are not normally included in the preparation outline
This is avoided because the ____ of the crown is significantly greater when this ridge is left intact
oblique ridges
strength
____ in the mandibular first premolars do not usually have a deep connecting fissure between the mesial and distal pits and not normally included in the preparation to avoid weakening the small lingual cusp
Some cases may be limited to a proximal
box preparation only – ____ PREP (usually for ____ preparations)
transverse
slot
composite
B and G: ____ to occlusal table and ____ to long axis of the tooth)
P and A: ____ external surface and pulpal chamber and ____ to long axis of the tooth
parallel
perpendicular
parallel
perpendicular
Class II Outline Forms
Man First Premolar
When preparing, tilt bur slightly ____ to establish correct pulpal wall direction
Pulpal wall will slope ____
Gingival wall is ____ to long axis of tooth
lingually
occlusally
perpendicular
Class II Outline Forms
Max/Man Premolars
Finished outline form including the ____, lingual extension (mand ____) , proximal box and ____ curve
Man Molars
Finished outline form including the buccal and lingual extensions, proximal box reverse S curve
No ____
dovetail
2nd
reverse S
dovetail
Class II Outline Forms
Max Molars
Due to oblique ridge
MO: Only mesial portion of occlusal surface is included
DO: Only distal portion of the tooth is involved
If oblique ridge is undermined, then ____
If distal caries and undermined oblique ridge, then ____ cavity will be prepared
If the oblique ridge is undermined, and the lingual groove has caries, then continue through ____ and ____
continue
MOD
ridge
groove
Principles of cavity design and preparation
External Outline Form Part I - Occlusal As in Class I Outline:
All carious ____
All ____ enamel
All ____ enamel
Molar Occlusal Outline: Extend into the major developmental grooves ____mm
pits and fissures
decalcified
undermined
1
External Outline Form - Occlusal
Try to keep isthmus width equal to or less than ____ the distance between the cuspal line angles
Occlusal Preparation
As in Class I Outline: Use 330 bur
____ mm into dentin (____ in the shallowest area)
Pulpal floor flat, smooth, and level
1/4
- 5
- 5
Principles of cavity design and preparation
External Outline Form Part II - Proximal
Opening is extended buccolingually and gingivally with 330 bur. As the box area deepens beyond depth of 330 bur, switch to the 245 bur.
____ motion
Proximal portion will be wider buccolingually at the ____ level and narrower at occlusal portion (retention)
A wooden wedge can be placed gingival to contact area:
Slightly opens the interproximal space and aids in preventing damage to the adjacent teeth
Aids in preventing injury to soft tissues *Also can place a matix band interproximally
pendulum
gingival
Proximal box placement and size is dictated by the ____
Clearance between the teeth is ____ mm, measured with the tip of the explorer along the entire buccal, lingual and gingival walls of the box
contact
0.5
Principles of cavity design and preparation
Outline Form - Proximal
May use a fissure 245 or 55 bur
Clinically, go gingivally until you break contact
Want at least ____mm long axial wall occlusogingivally
1
Principles of cavity design and preparation
External Outline Form Part III – S/Reverse S
Blend the occlusal outline and the proximal box outline
There is a very ____ angle at the junction
of the occlusal outline and proximal box
This is part of the outline but done to the outline to satisfy ____
Resistance Form – S/Reverse S
Want proper blending of box with occlusal part
Place a S-curve or reverse S where ever indicated
Besides blending Occlusal and Proximal outline forms, it allows “____” 90 degree angle of proximal walls
acute
resistance form
butt joint
Principles of cavity design and preparation
What determines where the reverse curve will be? PROXIMAL ____
It is often easy to break contact ____(embrasure spaces are larger) and a butt joint will be achieved without a reverse S curve
Most often ____
contact
lingually
buccally
Principles of cavity design and preparation
Internal Outline Form and Resistance Form
Pulpal wall
- developed ____ to long axis of tooth
- depth just into dentin
- perfectly flat
- where it joins axial wall, forms sharp axiopulpal line angle
Refinement
____ the axiopulpal line angle with ginigval margin trimmer
Plane gingival wall with gingival margin trimmer to remove unsupported enamel rods
Use a 169 or 170 bur to flare the occlusal wall bordering the marginal ridge by ____ degrees
perpendicular
round
3
Principles of cavity design and preparation
Internal Outline Form and Resistance Form
Gingival Wall
____ to long axis of tooth
____ mm in width M-D for premolars
____ mm in width M-D for molars
The Axial wall
____ with long axis of the tooth – Vertical wall
At least ____ mm deep O/G and M/D
Curves ____, parallel with the proximal surface of the tooth
The finished axial wall is just inside the____ (M-D orientation)
perpendicular 1.0 1.5 parallel 1 faciolingually DEJ
Principles of cavity design and preparation
Internal Outline Form and Retention Form
Convergent walls
Prevents occlusal ____ of amalgam
Dovetail on premolars:
Occlusal portion is widened in the opposing fossa toward the facial to include the ____ of the triangular fossa
Slightly ____ than the isthmus
Prevents proximal ____ of amalgam
Extensions into grooves on molars – no ____ needed
dislodgement fissures wider dislodgement dovetail
Principles of cavity design and preparation
Finishing margins
The cavity preparation is now refined with hand instruments
Facial and lingual walls form a 90 angle with the proximal surface of the tooth – ____ joint
Finish lateral proximal walls into smooth, flat surfaces with hatchets
Proximal facial and lingual walls are smoothed to blend with the facial and lingual walls of occlusal preparation
The Gingivocavosurface angle is planed to remove ____ enamel
The Axiopulpal line angle is smoothed
The Gingivocavosurface angle is ____ slightly to blend with facial
and lingual walls
butt
unsupported
rounded
20 DO
Preparations Completed in the GRD I Laboratory
Isthmus and lingual
extension is measured with the large end of the 1P condenser (isthmus – slightly ____, extension - ____)
Axial wall is ____ mm deep O/G
Gingival wall is ____ mm in width mesiodistally, and measured with the small hatchet
Isthmus is measured with the large end of the 1P condenser
(slightly ____)
Extension in Buccal and Lingual grooves ____ mm measured with the large end of the 1P condenser (____)
Axial wall is ____ mm deep O/G
Gingival wall is ____ mm in width M-D, and measured with the large hatchet
loose
snug
1.5
1
loose 1 snug 1 1.5
