Week3

Question 1

What is the objective of restorative dentistry

Answer 1

To replace diseased or lost tooth structure; restore tooth for function and appearance

Question 2

Dental materials in oral environment must be? (6)

Answer 2

Biocompatible
Durable
Nonreactive in acid or alkaline conditions
Compatible with other materials
Esthetically acceptable
Tolerable to differing temp & forces

Question 3

Dental materials are classified by their use which includes (3)

Answer 3

Preventive/ therapeutic materials
Restorative materials
Auxiliary materials

Question 4

What are examples of preventive /therapeutic materials

Answer 4

Pit and fissure sealants
Mouth guards
Fluoride

Question 5

What is a direct restoration

Answer 5

Placed immediately and directly into the prepared tooth in a pliable state then sets to harden

Question 6

What is an indirect restoration

Answer 6

Customized tooth replacements, fabricated in the lab

Question 7

What are examples of auxiliary materials

Answer 7

Impression materials
Gypsum
Dental waxes
Finishing and polishing materials

Question 8

What is a nickel allergy

Answer 8

Adverse response from breakdown of the materials components (nickel) in oral environment

Question 9

What is force

Answer 9

Push pull or twist or a combination of these

Question 10

What is stress

Answer 10

The force (weight) applied at the surface will create stress within the object that tries to resist the weight

Question 11

What is strain

Answer 11

The amount of change that the force has produced on the object

Question 12

What is normal Masticatory forces on the occlusal surface of molar teeth

Answer 12

28,000 lbs/square inch on a cusp tip

Question 13

What are the 3 basic types of forces

Answer 13

Compressive (pushing together)
Tensile (pulls and stretches)
Shearing (slice apart)

Question 14

Compressive forces deal with which teeth

Answer 14

Posterior teeth

Question 15

Torsion force is aka

Answer 15

Torque

Question 16

Describe torsion force (torque)

Answer 16

Twisting force that has tensile and compressive forces
-descriptive of normal Masticatory events

Question 17

What is flexural stress

Answer 17

Bending stress
Combo of tension and compression

Question 18

What is more likely to fracture under compressive stresses

Answer 18

Porcelain

Question 19

Desirable materials should have ___ solubility

Answer 19

Low solubility

Question 20

What are examples of materials with low solubility

Answer 20

Gold and porcelain

Question 21

What is galvanism

Answer 21

Phenomenon of electrical current being transmitted between two dissimilar metals

Question 22

What is the current that may result in stimulation to the pulp

Answer 22

Galvanic shock

Question 23

What are excellent thermal conductors

Answer 23

Metals

Question 24

What are poor thermal conductors

Answer 24

Non metals (ceramics, composite resins)

Question 25

Dental materials in the mouth are subjected to temperature changes which can result in

Answer 25

Thermal expansion

Question 26

If the thermal expansion of the restoration does not match the expansion of the tooth what may occur

Answer 26

Microleakage

Question 27

What is percolation

Answer 27

The space between the tooth and the restoration

Question 28

What is interface

Answer 28

The space between the walls of the preparation and the restoration

Question 29

Mechanical retention involves the use of

Answer 29

Undercuts or other projections into which the material is locked in place

Question 30

The surface of composite resins may have

Answer 30

A rougher surface than enamel

Question 31

What aids in the identification/detection of restorative materials

Answer 31

Illumination and air

Question 32

For a restorative material to function properly it must be (3)

Answer 32

Hard (hardness) Strong (yield strength) Stiff (modulus)

Question 33

What are the three basic forms that materials may take on

Answer 33

Solid Liquid Gas

Question 34

What is a defining characteristic of a solid

Answer 34

Is has shape and volume

Question 35

If the pattern are arranged in a random form with no pattern the solid is less

Answer 35

Stable (amorphous)

Question 36

The denser the material is the less

Answer 36

Air or spacing there is between atoms

Question 37

Which tooth structure is described as being the most dense

Answer 37

Enamel

Question 38

Which restorative material is classified as being the most dense

Answer 38

Gold

Question 39

Hardness is used to define a materials resistance to

Answer 39

Wear and abrasion

Question 40

Tooth structure and biomaterial that are classified as the hardest materials and more resistant to being scratched

Answer 40

Enamel Porcelain

Question 41

What tests can be done to test hardness

Answer 41

Knoop test Rockwell test

Question 42

What is ultimate strength

Answer 42

Max amount of stress a material can withstand without breaking

Question 43

If the deformation is not permanent and the material recovers from the force completely then

Answer 43

It has good elasticity

Question 44

What is stiffness and what is it measured by

Answer 44

Resistance to deformation of a biomaterial and is measured by young’s elastic modulus

Question 45

Suffer materials have a _____ modulus

Answer 45

Higher

Question 46

High value (modulus elastic value) indicates that the material is

Answer 46

Very rigid (enamel)

Question 47

Low value (modulus elastic value) indicates the material is

Answer 47

Flexible

Question 48

What is proportional limit

Answer 48

The greatest stress a structure can withstand without permanent deformation

Question 49

When stress exceeds this point called the proportional limit the object

Answer 49

Does not return to its original shape

Question 50

What is resilience Example?

Answer 50

The resistance of a biomaterial to permanently deform (Ortho arch wire)

Question 51

What is toughness

Answer 51

Ability of a biomaterial to resist fracture

Question 52

What is malleability

Answer 52

Ability for a material to be compressed without breaking

Question 53

Ductility is the

Answer 53

Amount of dimensional change a material can withstand without breaking -materials with poor ductility are classified as brittle

Question 54

What is fatigue in terms of dental materials

Answer 54

Occurs within a material when it is subjected to repeat stresses; can result in sudden failure or fracture of the material

Question 55

Viscosity refers to

Answer 55

The resistance of a liquid to flow

Question 56

Thin fluids have

Answer 56

Low viscosity

Question 57

Thick fluid have

Answer 57

High viscosity

Question 58

The viscosity of a liquid usually _____ as the temp increases

Answer 58

Decreases

Question 59

What are thixotropic materials

Answer 59

Liquids that flow more easily under mechanical forces (Ex. Fluoride gel)

Question 60

What are examples of direct restorations

Answer 60

Amalgam Composite Sealants

Question 61

What are examples of indirect restorations

Answer 61

Inlays Onlays Crowns Bridges Implants

Question 62

What is the manipulation stage

Answer 62

Mixing and working time

Question 63

What is reaction stage

Answer 63

Initial and final set

Question 64

Mixing time refers to

Answer 64

Length of time from beginning of mixing time to the beginning of working time

Question 65

Working time refers to

Answer 65

Time permitted to manipulate the material in the mouth

Question 66

Initial set time refers to

Answer 66

Time begins when the dental material no longer can be manipulated in the mouth

Question 67

Final set time refers to

Answer 67

Material has reached its ultimate state

Question 68

High temperatures and humidity will accelerate the

Answer 68

Reaction of the material