Inlays, Onlays and Crowns Revision Questions

Question 1

Ceramic inlay prep

Answer 1

1.5mm - 2mm = isthmus
1.5mm depth
1.5mm-2mm = proximal bonx
1mm shoulder/chamfer margin

Question 2

Gold inlay prep

Answer 2

1mm = isthmus
1.5mm depth
1mm proximal box
0.5mm chamfer margin

Question 3

Key things to prep of inlay

Answer 3

Dovetail/occlusal key to improve retention
4-6 degree tapered walls and round internal line angles
Grooves for additional retention

Question 4

Procelain onlays prep

Answer 4

1.5mm reduction = non working cusp
2mm reduction = working cusp
1mm = shoudler/chamfer margin

Question 5

Gold onlays prep

Answer 5

0.5mm reduction = non working cusp
1mm reduction = working cusp
0.5mm = chamfer margin

Question 6

What is gingival retraction cord?

Answer 6

Expresses tissue fluid from gingival compressing allowing exposure of cavosurface margins to allow impression to be injected into area in mositure free
Placed for 2mins