Lecture 2

Question 1

three basic principles of tooth preparation

Answer 1

biologic (conservation of tooth structure)
mechanical
esthetic

Question 2

the poor appearance of some metal-ceramic restorations is often due to what

Answer 2

insufficient porcelain thickness

Question 3

what are the parameters for the biologic width?

Answer 3

3mm btw restoration and bone

Question 4

the more accurately the restoration is adapted to the tooth, the less the chance for what?

Answer 4

recurrent caries or periodontal disease

Question 5

what is the recommended convergence angle of the axial walls?

Answer 5

6 degrees

Question 6

the location of the finish line for #21 should be ____ and #19 should be

Answer 6

.75mm (bc of the shoulder)

.5mm (typical chamfer)

Question 7

which POW should you choose when making an FPD?

Answer 7

always choose the molar POW

Question 8

the first plane grooves should be what?

Answer 8

parallel to the long axis of the tooth

Question 9

how many planes of reduction are there for a #21

Answer 9

3 (fxnal cusp, 1rst plane, second plane)

Question 10

the shoulder should be how long?

Answer 10

1.2-1.5 mm

Question 11

you should prepare all abutments at the same time to minimize what?

Answer 11

undercuts

Question 12

retention form

Answer 12

forces parallel to long axis

Question 13

resistance form

Answer 13

lateral forces (occlusal forces)

Question 14

what angle should the shoulder be?

Answer 14

120 degrees

Question 15

advantages of supra gingival margins

Answer 15

easily finished
impressions more easy
restoration can be more easily evaluated
more easily cleansed

Question 16

indications of sub gingival margins

Answer 16

• presence of caries, cervical lesions, or restorations that extend subgingivally
• need for additional retention
• root sensitivity
• need to hide the margin of a metal-ceramic crown for esthetics on anteriors