Lec 1/12 Principle of Tooth Prep

Question 1

5 princ of tooth prep:

Answer 1

preserve tooth, retention/ resistnace, structural durability, marginal integrity, preservation of periodontium

Question 2

3 major groups to consider hen thinking about principles of tooth prep:

Answer 2

Biologic, mechanical, esthetics

Question 3

Mechanical principles:

Answer 3

provide retention and resistance, prevent deformation of resto

Question 4

This form prevent any movement of the resto under occlusal forces:

Answer 4

resistance

Question 5

6 factors influencing retention:

Answer 5

magnitude of force, geometry of tooth prep, roughness of intaglio surface, materials being cemented, luting agent used, film thickness of luting agent

Question 6

These forces tend to remove a resto along its POI:

Answer 6

dislodging, chewing sticky food

Question 7

Magnitude of dislodging forces depends on:

Answer 7

stickiness of food, sa of the resto, surface texture of the outer surface of resto

Question 8

Factors included in geometry of a prep:

Answer 8

diameter, taper, height/ length

Question 9

Does an inc in ht inc retention more or less than a greater inc in parallelism of the axial walls?

Answer 9

less

Question 10

How does an inc in diameter affect retention?

Answer 10

linear inc in retention

Question 11

Result of occ surface of prep not following unprepped tooth:

Answer 11

ht dec, sa dec (frictional dec)

Question 12

Type of crown, best to worst retention:

Answer 12

complete crown w no grooves, 7/8 crown w grooves, 3/4 crown w grooves, 7/8 crown, 3/4 crown (sa decreases)

Question 13

Luting agents, greatest % retention to least % retention of zinc phosphate:

Answer 13

adhesive resin, resin, GI, polycarboxylate

Question 14

Good resistance depends on these 3 things:

Answer 14

magnitude/ direction of forces, geometry of tooth prep, physical properties of luting agent

Question 15

Are boxes or grooves more retentive?

Answer 15

boxes

Question 16

Clinically acceptable range of prep ta[per:

Answer 16

5-22’

Question 17

Tooth prep w lowest resistance form:

Answer 17

short, large diameter, large taper

Question 18

Which require more parallel preps to get resistance form, molars or premolars?

Answer 18

molars

Question 19

Luting agents, can undergo greatest to least compressive strength:

Answer 19

adhesive resin, resin, resin ionomer, GI, polycarboxylate, zinc phosphate

Question 20

Biological consideration:

Answer 20

prevention of damage to tooth, adjacent teeth, soft tissue, pulp

Question 21

Causes of injury of biological concern:

Answer 21

temp, chemicals, bacterial action

Question 22

TF? Both air turbine water cooled, and low speed water cooled show less of a temp inc than either air turbine or low speed, dry.

Answer 22

T

Question 23

Biological consideration that affect health of oral tissues:

Answer 23

conservation of tooth structure, avoidance of overcontouring, supragingival margins, harmonious occlusion, protection against tooth fracture

Question 24

Margin design requires a design that can provide enough:

Answer 24

bulk of material to resist deformation

Question 25

TF? Feather edge margin provides enough bulk of gold alloy to withstand distortion.

Answer 25

F

Question 26

7 margin designs:

Answer 26

Feather edge, chisel, chamfer, Bevel, Shoulder, Sloped Shoulder, Beveled Shoulder (no modified shoulder!!)

Question 27

Is bevel margin essentially a sloped chamfer margin?

Answer 27

check

Question 28

Margin design most suitable for cast metal crowns ans the metal-only portion of a metal-ceramic crown:

Answer 28

chamfer

Question 29

Benefits of supragingival margins:

Answer 29

easily finished, easily cleaned, impressions easy to make, restos easily evaluated (adaptation of the margin?)

Question 30

Areas of critical reflectance that are esthetic concern:

Answer 30

most I & G portions of the PFM that have both metal and porcelain (doesn’t inc most F-G area that is all metal or area that is most incisal that is all porcelain