Week 2 Class I and V Preparations Flashcards
what are tools you can use for isolation
-rubber dam
- cotton rolls
- retraction cord
- isovac
how deep are ideal preparations into dentin
0.2-0.5 mm
what is the traditional teaching technique about the outline form of an amalgam preparation
the prep must not terminate in the bottom of a fissured pit or groove
where is contact broken on class II amalgams
facially and lingually
what is retention form
what retains the restoration
what is amalgam held in by
converging walls and/or retention grooves
what is resistance form
elements in the design of a tooth prep that will help restoration and tooth resist fracturing
what makes a restored tooth less likely to fracture
- maintaining as much tooth structure as possible
- having some areas on the floor of a multi surface preparation that are perpendicular to occlusal forces
- rounding internal line angles
- smoothly rounding outline form
what factors are important to keep in mind when preparing to proper depth
-never leave enamel on the floor of a prep
- never leave a partial depth ledge on the enamel wall of an occlusal prep
where is a buccal pit amalgam class 1 located
in occlusal 2/3 of molar tooth
what depth should a buccal pit class 1 be
1.8 mm
how much do walls at the terminal ends of buccal and lingual grooves in a class 1 diverge
3 degrees
how much do walls in the isthmus area converge
3 degrees on each side
how big is the isthmus width on a class 1 prep
1 mm minumum
how much do walls adjacent to marginal ridges diverse
3 degrees
why diverge the mesial/ distal wall adjacent to the marginal ridge
leaves dentin support for the ridge in this area
what should the occlusal amalgam depth be in relation to DEJ
.2 mm inside DEJ
what should the occlusal amalgam depth of plastic molars be? premolars?
molars: 2 mm total
premolars: 1.5-2 mm total
what would be the risk of converging walls adjacent to the marginal ridges on a class 1
destruction of the dentin support for the marginal ridge
which direction M/D does the bur incline more in the mandible? maxilla?
mandible: mesially
maxillar: distally
why does the bur incline differently M/D in each arch
curve of spee
what direction (B/L) does the bur incline more in the mandible? maxilla?
mandible: lingually
maxilla: buccally
why does the bur incline differently B/L in each arch
curve of wilson
how deep should the prep be for a class 1 occlusal amalgam prep
1.5 mm
what walls does a 330 bur give you? 169?
330: converging
169- diverging
how long is the 169 bur
4 mm
what type of bur is a 169
tapered fissure bur
how long is a 330 bur
1.8 mm
at 1.5 mm depth prep on occlusal surface of molar have you reached the dentin
NO
what type of bur is a 245 bur and how long is it
-inverted cone bur
- 3 mm
what will a 245 bur do if held in one plane
can an undercut prep with rounded internal line angles
what will a 169 bur do to line angles
make them sharp
what should the walls look like on a class I occlusal amalgam prep
diverge
what is a class V
gingival 3rd of the buccal and lingual surfaces of teeth
where do almost all carries start
supragingivally
what is the outline form determined by in a class V amalgam prep
the extent of the caries rather than the anatomy
what degree and angle do the margins in a class V amalgam prep need to be
90 degrees, diverging
how deep should the class V buccal amalgam prep be
1.5 mm
what burs should you use for the class V buccal amalgam prep
-#2 round bur on slow speed to excavate caries
- #169 at high speed to refine internal line angles and cavosurface margins
how deep do you drill when there is minimal thickness of enaml in a class V buccal amalgam prep
1 mm
how deep do you drill when the margin is on the root in a class V buccal amalgam prep
0.75 mm
where is the retention groove and what bur do you use for a class 5 amalgam prep
entirely in dentin just inside the DEJ, use a 1/4 round bur
where do retention grooves go inside deep preps
still go just inside the DEJ
how do you remove caries that extend into the interproximal embrasures
-excavate caries with #2 round bur
- use a gingival margin trimmer to remove undermined enamel interproximally
- use end of 169 bur to define internal line angles interproximally
