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Operative II > Week 2 - Class II Prep and Restorations > Flashcards

Week 2 - Class II Prep and Restorations Flashcards

1
Q

what is the purpose of the s curve

A
  • creates smoothly rounded form to improve resistance to fracture
  • keeps narrowest part of preparation away from axiopulpal line angle to improve resistance to fracture
  • allows preparation to break contact while allowing buccal wall to meet the tooth surface at a 90 degree exit angle
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2
Q

how big should the buccal contact, gingival contact and lingual contact be open in a class II amalgam

A
  • buccal: 0.2-0.5mm
  • gingival: at least 0.5mm
  • lingual: 0.2-0.5mm
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3
Q

what does the 0.5 mm open gingival contact ensure

A

the caries susceptibel area below the contact is clear

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4
Q

what should be the degree of convergence for each the buccal and lingual wall in class II

A

3-4 degree convergence

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5
Q

what should you use to remove undermined enamel hooks

A

enamel hatchet

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6
Q

what should you use to smooth the gingival floor

A

56 or 57 bur or 245

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7
Q

how are enamel rods inclined

A

gingivally

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8
Q

how should you smooth the gingival floor with a 56 o 57

A
  • bur has sharp edges that leave sharp internal line angles that must be rounded
  • remaining undermined enamel on gingival margin will need to be trimmed away with hand instrument
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9
Q

how should you smooth the gingival floor with a 245 bur

A
  • bur has slightly rounded edges leaving more roundness at the internal line angles
  • more difficult to smooth gingival floor with this than the 56 or 57
  • need to use hand instrument to remove undermined enamel
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10
Q

how should you bevel the axiopulpal line angle

A
  • use flat end of a 56 or 57 straight fissure bur to put a 45 degree bevel on the axiopulpal line angle
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11
Q

what is the benefit of approaching the axiopulpal line angle to bevel through an open portion of the box

A

less likely to nick the surrounding tooth structure compared to using the side of a 169 or 7902 flame bur

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12
Q

what does a reverse S curve starting too far distally cause

A

weakening cusp

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13
Q

what does no reverse S curve cause

A

weak amalgam

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14
Q

what does flare for reverse S curve starting too far mesially cause

A

amalgam prone to fracture

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15
Q

what does a concave axial wall cause

A

compromised resistance and retention form

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16
Q

what is the axial wall depth for a composite

A

1-1.5mm

17
Q

what should be beveled in a composite prep

A
  • lingual wall
  • gingival bevel
  • axiopulpal line angle
18
Q

what is the benefit of keeping margins in enamel

A

minimize microleakage and post op sensitivity

19
Q

what are the main differences between composite and amalgam preps

A
  • composite preps can be more conservative
  • bonding capability of composite may strengthen supporting tooth structure
20
Q

what are the contraindications to composite

A
  • occlusion
  • restorations extending to root surface
  • deep sub gingival margins
21
Q

what are the advantages of composite

A
  • esthetic
  • conserves tooth structure
  • bonding
  • no metal
  • can be economical
  • prep can be more forgiving
22
Q

what are the advantages of the bonding in composites

A

-reduced microleakage and recurrent decay
- increased retention

23
Q

what are the advatnages of no metal in composites

A
  • no mercury arguments from patients
  • no corrosion
  • no galvanic shock
24
Q

what are the disadvantages of composite

A
  • low modulus of elasticity
  • porous
  • more technique sensitivie placement
  • more time consuming placement
  • microleakage
  • may stick to instrument, resulting in voids
  • cant place in bulk
  • expensive compared to amalgam
25
Q

why should you not use a clear matrix band with composite

A
  • too much flash
  • poor contours
  • reservoir for moisture
  • overall terrible
26
Q

what can you do to avoid dessicating dentin

A

place a cotton pellet over it

27
Q

what is the oxygen inhibited layer

A

the sticky uncured layer left of the surface
- oxygen in the air interferes with polymerization on surface of composite
- this facilitates bonding to the next layer added

28
Q

what are the new things to be considered with composite

A
  • interproximal contacts
  • voids
    -light
    -polymerization stress
29
Q

how do you insert the band into the tofflemire retainer

A
  • turn the inner nut counterclockwise until slot vice is about 1/4 inch from the guide channels
  • hold the inner nut and turn the outer nut clockwise until the pointed end of the spindle is free of the slot in the slot vice
  • double the band back on itself forming a loop
  • insert into the slot vice and direct it through one of the three guide channels and tighten spindle
30
Q

where is the wider opening in the loop of the matrix band

A

toward the occlusal of the tooth

31
Q

where is the slot vice in relation to the tooth

A

toward the gingival of the tooth

32
Q

when is the retainer of the tofflemire on the lingual side of the tooth and what does it require

A
  • useful with missing buccal tooth structure
  • requires use of a contra angle retainer
33
Q

what is the purpose of the wooden wedge

A

to close the margin at the gingival of the box and prevent overhand

34
Q

when would double wedging be done

A

if you have a wide interproximal space and a gingivally deep box

35
Q

when would you vertically stack two wedges

A

in event of gingival recession and a proximal box of moderate depth

36
Q

when would you use interproximal fluting

A

root concavity

37
Q

where should the occlusal stop be in MI and why

A

bottom of the fosaa to put long axis forces on the teeth

38
Q

what happens if you carve grooves so deep that no stop is created in MI

A

the teeth may later erupt to re achieve contact but the forces may not be down the long axis of the teeth

39
Q
A

Operative II (10 decks)

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