Manual Definitions

Question 1

The maximum stress a material can endure before failure (fracture). It is an important property of any dental restorative material which is subject to significant stress.

Answer 1

Ultimate Tensile Strength (UTS)

Question 2

The stress that is required to permanently deform a material a specific amount (usually 0.1-0.2%). It is particularly important to consider in the selection of an alloy for FPDs. Not important in the discussion of ceramics because they are brittle.

Answer 2

Yield Strength

Question 3

The slope of the elastic region of the stress-strain curve. The measure of the material’s stiffness or resistance to deformation.

Answer 3

Modulus of Elasticity

Question 4

The amount of permanent strain or deformation which occurs in a material at the point of fracture. A measure of the alloy’s ductility.

Answer 4

Elongation

Question 5

The resistance of a material to withstand penetration or permanent indentation. This can influence potential wear characteristics.

Answer 5

Hardness

Question 6

The ratio of mass to volume of a material. It is of particular importance in the consideration of casting alloys during the casting procedure.

Answer 6

Density

Question 7

Characteristics that are of particular importance for biocompatibility.

Answer 7

Tarnish and Corrosion

Question 8

The change in length per unit of material for 1 degree change in temperature.

Answer 8

Thermal Expansion

Question 9

Color and translucency characteristics are the most important of this category.

Answer 9

Optical Properties

Question 10

Inlay Golds are Type ____ or Type ____ alloys.

Answer 10

Type I (soft) or Type II (medium)

Question 11

Crown and Bridge alloys are Type ____ or Type ____.

Answer 11

Type III (hard) or Type IV (extra hard)

Question 12

Metal Ceramic Alloys are either _____ or ______.

Answer 12

Hard or Extra-Hard

Question 13

Casting alloys are classified based on the noble metal (Au, Pd, Pt) content in what percentages?

Answer 13

> 80% Au = very high noble metal
60% noble metal (>40% Au) = high noble metal
25% noble metal (no Au requir.) = noble metal
below 25% noble (no Au requir.) = predom. base metal

Question 14

The noble metal alloy “Gold-Platinum-Palladium” would be considered a _________.

Answer 14

Very High Noble Metal

Question 15

Which properties would be ideal for an alloy in metal ceramic restorations?

Answer 15

1. High corrosion/tarnish resistance
2. High Strength
3. High Elastic Modulus
4. Closely matched thermal expansion
5. Bonding and wetability
6. Good Optical properties
7. Decent tensile strength

Question 16

How does a porcelain “wet the surface” of a metal?

Answer 16

By forming an oxide layer on the metal to facilitate the setting process. Chemical and mechanical mechanisms are involved.

Question 17

Are noble metals able to form an oxide layer for bonding?

Answer 17

No, pure noble metals must have other elements adding in small amounts in order to obtain an oxide layer and achieve good bonding.

Question 18

What are the two alloy systems used in the clinics for ceramo-metal single unit and FPD?

Answer 18

1. Freedom Plus (noble- 78%Pd)
2. Olympia (high noble- 51.5% Au)
   * these are not yellow*

Question 19

Do Freedom Plus and Olympia alloy systems have elements added in order to help form an oxide layer?

Answer 19

Yes: Copper (Cu), Indium (In), and Gallium (Ga)

Question 20

Which material in the clinic is classified as Very High Noble Metal, containing 90% gold?

Answer 20

Jelenko O

Question 21

Which alloy is used in the clinic for fabrication of CVCs and is classified as Noble (46%Au)? What does this product lack?

Answer 21

Midas

Lacks oxide-forming capabilities (cant bond porcelain)

Question 22

What is the primary reason for choosing porcelain?

Answer 22

esthetics

Question 23

True or False: Porcelain is the most biocompatible dental material in use due to its high corrosion resistance and low solubility in the oral cavity.

Answer 23

True

Question 24

Which property of porcelain can be related to “abrasion resistance”?

Answer 24

Hardness

Question 25

True or False: Natural tooth enamel is softer than porcelain and wear of opposing teeth must be considered.

Answer 25

True

Question 26

Ceramics have generally _____ thermal expansions compared to metals.

Answer 26

Lower

Question 27

The process of mixing feldspar, quartz, and kaolin at high temperatures and then rapidly cooled by quenching.

Answer 27

Fritting

Question 28

Porcelain is primarily _____ matrix with dispersed crystalline structures.

Answer 28

glass

Question 29

By controlling the percentage of ______ present in the final composition of porcelain, the thermal expansion can be made to approximately match the alloy.

Answer 29

Leucite

Question 30

The process by which the porcelain powders are drawn together and condensed under high temperatures as a result of viscous flow; leading to volumetric shrinkage.

Answer 30

Sintering

Question 31

There are generally at least ____ different porcelain layers which are veneered over the metal to produce a tooth-like appearance.

Answer 31

Three

Question 32

What are the three layers of porcelain that are layered to create a tooth-like appearance?

Answer 32

Opaque- aids bonding, highly reflective
Body (Dentin)- medium translucency, color
Incisal (Enamel)- high translucency