Week 7 Class II Preps

Question 1

where are initial caries located

Answer 1

entirely in enamel

Question 2

where are moderate caries located

Answer 2

lesion entering dentin

Question 3

where are advanced caries located

Answer 3

well into dentin- approaching pulp
- or if root caries: lesion entering dentin

Question 4

where do caries start in interproximal caries

Answer 4

below the contact

Question 5

what is the dentists goal in interproximal caries

Answer 5

-remove carious tooth structure
- remove the least amount of tooth structure possible
- prepare the tooth in a way that resists fracture and retains the restoration

Question 6

where is the S curve placed

Answer 6

on the buccal side

Question 7

what is the purpose of the S curve in amalgam preps

Answer 7

• improves resistance to amalgam fracture
• keeps narrowest part of preparation away from axiopulpal line angle

Question 8

how much should the buccal and lingual contact be open

Answer 8

0.02-0.5 mm

Question 9

how much should gingival contact be open and why

Answer 9

• at least 0.5mm to ensure the caries susceptible area below the contact is clear

Question 10

what are the steps in a class II amalgam prep

Answer 10

1. complete a class 1 amalgam prep
2. widen the dovetail faciolingually and thin the marginal ridge to about 0.5-0.8mm mesiodistally
   3.ditch for the box with 3-4 degree convergence
3. break through the thin enamel wall
4. remove undermined enamel hooks
5. smooth the gingival floor
6. bevel the axiopulpal line angle
7. remove undermined enamel from the gingival margin
8. smooth walls, perfect outline, and finish the prep
9. place retention grooves

Question 11

what burs could you use to smooth the gingival floor

Answer 11

56,57, or 245

Question 12

what should you use to bevel the axiopulpal line angle

Answer 12

flat end of a 56 or 57

Question 13

what is the purpose of the retention grooves

Answer 13

to retain the amalgam segment that fills the box against interproximal displacement

Question 14

how deep should the retention grooves be

Answer 14

just inside the DEJ entirely in dentin or about .5mm

Question 15

where should the retention grooves be

Answer 15

buccal axial and lingual axial and gingival axial

Question 16

what tooth is the exception for path of entry

Answer 16

-mandibular first premolar- the long axis of the crown of this tooth tilts lingually relative to long axis of the tooth root
- a class I or II prep should enter parallel to the long axis of the tooth crown to preserve strength in the small lingual cusp

Question 17

what are the properties of composite

Answer 17

-preps can be more conservative
-bonding capability of the composite may strengthen supporting tooth structure
- composite is a good insulator

Question 18

what are indications for composite

Answer 18

-esthetics
-light occlusal contacts
-smaller restorations
-isolation

Question 19

why must composite use be for light occlusal contacts

Answer 19

-must have centric tooth supported occlusion on marginal ridges and cusp tips because composite does not support occlusion

Question 20

what type of small restorations are indications for composite

Answer 20

-class 1 occlusal, buccal pits and lingual pits: low stress areas and premolars > molars
- small class 2 restorations
-margins must be kept in enamel and beveled
- minimize microleakage and post op sensitivity

Question 21

what are the special situations for indications for composite

Answer 21

-crown foundation- “buildup”
- very large restorations- to strengthen remaining weakened tooth structure for economic reasons or temporarily
- conservative or preventative restorations- sealants
- temperature sensitivity with metal restorations
-cross reaction between nickel allergy and silver

Question 22

what is not an indication for composite

Answer 22

-mercury fear
- ALS and MS patients

Question 23

what are contraindications to composite

Answer 23

-heavy occlusal forces
- occlusal contacts entirely on composite
- restorations extending to root surface
-deep subgingival margins
-diet (high acidic environment, high alcohol consumption)
- poor oral hygiene
- unable to isolate

Question 24

why does composite fail

Answer 24

-dentin tubules - as preps get deeper theres more fluid in tubules
- adhesives-water based adhesives undergo phase separation
- etch- operator error, if etch too long tubules collapse
- orientation of enamel vs dentin
- polymerization shrinkage

Question 25

what are the advantages to composite

Answer 25

-esthetic
- conserves tooth structure
- bonding
-no metal
- economical
- preparations may be more forgiving (although restorations are not)

Question 26

what is the advantage about bonding with composite

Answer 26

-reduced microleakage and recurrent decay
-increased retention

Question 27

what is the advantage of no metal with composite

Answer 27

-no mercury agruments
- no corrosion
- no galvanic shock

Question 28

what are the disadvantages of composite

Answer 28

-low modulus of elasticity
- porous
- more technique sensitive placement
- more time consuming placement
- microleakage
- may stick to instrument resulting in voids
- cant place in bulk
- expensive compared to amalgam

Question 29

where should the bevels be placed in a composite restoration

Answer 29

• lingual wall bevel
• gingival bevel
• axial-pulpal line angle bevel

Question 30

when should you not do a bevel

Answer 30

if gingival floor is in dentin or cementum