basics of tooth preparation

Question 1

remember
Tooth preparation is a balance between sufficient tooth reduction for restorative material and retention and preservation of tooth tissues

Question 2

why is it important during tooth preparation to conserve tooth structure 2

Answer 2

To maintain the tooth strength and protect the pulp

Maintain resistance and retention form

Question 3

what happens if you don’t prepare the tooth enough for a crown? 2

Answer 3

Thin crown -> poor aesthetics, inadequate strength

Overbuilt crown -> plaque retention, poor aesthetics

Question 4

what is retention form?

Answer 4

Ability to retain a restoration in an occlusal direction

Question 5

what is resistance form?

Answer 5

Ability to prevent dislodgement of a restoration to lateral and oblique forces

Question 6

why is a short tapered preparation bad?

Answer 6

increases shear force and chance of crown loss

Question 7

what is the ideal degree of taper of a crown prep?

Answer 7

6 degrees

Question 8

what are used in round preparations to prevent rotation?

Answer 8

grooves

Question 9

tooth prep for a metal crown
wall thickness: ?
occlusal thickness: ?
finishing margin:

Answer 9

0.5mm
1mm
any type

Question 10

tooth prep for metal ceramic crown
wall thickness: ?
occlusal thickness: ?
finishing margin: ?

Answer 10

1.5mm
1-2mm
shoulder for ceramic and chamfer for metal mm

Question 11

tooth prep for ceramic/composite crown
wall thickness: ?
occlusal thickness: ?
finishing margin: ?

Answer 11

0.6-1mm
1-1.5mm
chamfer margin - sharp angles can cause cracks in ceramic

Question 12

where should the finishing margins be located? 3

Answer 12

On sound tooth structure

Below the contact point

Not subgingival

Question 13

remember
Finishing margins should follow and be as close as possible to gingival margin without disrupting the periodontium