Wk 6: Onlay Prep #4

Question 1

Reduction for Ceramic MOD onlay #4 prep:

Answer 1

1.5mm at lingual cusp, 1.5mm more axial at the margin, 1mm L margin using 6847KR-016, extended past the CG about 2mm at CG, 1mm from CEJ at D contact, 6-10’ divergence of B and L internal walls (angulation of tip of bur), 0.5mm proximal clearance, 2mm B-L width for proximal box, 1.5mm depth at proximal areas, 1.5mm BL width at center of isthmus

Question 2

Bur for prep occlusal outline:

Answer 2

KR-018, green diamond

Question 3

KR-018, green diamond width at tip:

Answer 3

1.3mm

Question 4

Depth to reduce occlusally with green diamond:

Answer 4

1.8mm, 0.2mm for finishing check

Question 5

Orientation of bur for prepping proximal boxes:

Answer 5

advance bur G then B and L, in the precise POI of the prep

Question 6

Why is a 0.5mm clearance required?

Answer 6

for impression making

Question 7

What does correct G, B, and L extension of the prep depend upon?

Answer 7

the contact area w the adjacent tooth

Question 8

How to create additional clearance at the cusp tip:

Answer 8

bur more horizontal than intended resto cusp

Question 9

Depth of depth grooves for lingual cusp:

Answer 9

1.3mm leaving 0.2mm for finishing

Question 10

Depth of depth groove for the nonfunctional cusp:

Answer 10

0.8mm leaving 0.2mm for smoothing

Question 11

Orientation of bur when reducing nonfunctional cusps:

Answer 11

parallel to the cusp inclines

Question 12

Axial wall on functional cusp:

Answer 12

1mm functional cusp ledge

Question 13

Bur for functional cusp ledge prep:

Answer 13

cylindrical carbide bur

Question 14

Fxn of functional cusp ledge

Answer 14

gives restoration bulk in a high-stress area preventing deformation during function

Question 15

Placement of functional cusp ledge in relation to opposing central contacts:

Answer 15

1mm apical to it

Question 16

How far does axial wall on functional cusp extend?

Answer 16

into the proximal box, not too far apical

Question 17

What would happen if the axial wall on functional cusp is placed too far apically?

Answer 17

resistance form from the boxes will be lost

Question 18

Bur to refine outline form:

Answer 18

8845KR

Question 19

Cavosurface angle should be:

Answer 19

90’

Question 20

How much hygienic (at proximal contacts?) clearance is necessary?

Answer 20

0.5mm

Question 21

Place where sharp angles are likely:

Answer 21

junction of the ledge and occlusal surface

Question 22

how to check occlusal reduction:

Answer 22

Have pt close into GC pattern and measure w a thickness gauge

Question 23

Is the internal outline curved more on the B or L?

Answer 23

B

Question 24

Easy way to remember reductions:

Answer 24

3 1.5mm steps

Question 25

Orientation of bur when shaping proximal box:

Answer 25

bur parallel to long axis

Question 26

The proximal axial walls should be convex/ concave. B-L

Answer 26

concave

Question 27

The internal form of the B wall of the prep should be concave/convex in the MD direction:

Answer 27

convex

Question 28

To where should the occlusal depth extend:

Answer 28

just beyond enamel-dentin junction

Question 29

Onlay boxes are preppe din the same manner s:

Answer 29

inlay preps

Question 30

TF? nonfunctional cusp must always be reduced for onlays.

Answer 30

F

Question 31

The axial wall on functional cusp extend to here:

Answer 31

into the proximal boxes