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Dental Materials > Testing of Dental materials > Flashcards

Testing of Dental materials Flashcards

1
Q

compression strength in test

A

shear forces along the cone-shaped area at each end
tensile forces central portion of the mass
compression forces on the ends

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2
Q

permanent bending

A

used to measure the number of bends the specimen will withstand and to compare different composition and dimensions as well as its treatment in fabrication.
eg. orthodontic wires and removable denture clasps

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3
Q

Diametral tensile strength test

A

test for tensile strength that is only used for materials that exhibit predominantly elastic deformation and little or no plastic deformation.
basically not for brittle materials

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4
Q

shear strength

A

the max stress that a material can withstand before failure in a shear mode load
eg. a metal bracket used for braces

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5
Q

fatigue strength

A

the stress level at which a material fails under repeated loading

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6
Q

fatigue strength testing

A

subjecting a specimen to alternating stress applications below its yield strength until fracture occurs.
stress may be: tensile, compressive, shear, bending, and torsion

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7
Q

what fractographic analysis

A

the study of fracture surfaces of materials.

helps to define the cause of failures and aid in the structural design, as well as to improve existing materials

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8
Q

what is tear strength

A

the measure of resistance of a material to tearing forces

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9
Q

what is hardness

A

the resistance of a material to suffer indentation, scratching, or bending

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10
Q

how is hardness tested?

A

applying a standardized force or weight to an indenter

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11
Q

Brinell Hardness test

A

using a spherical indenter to penetrate the material.

after hitting the material the diameter is measured of the dent.

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12
Q

Knoop Hardness test

A

a material is indented with a diamond shape and then the height and length of the indentation is measured

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13
Q

Vickers Hardness test

A

measure of the surface area of the pyramid indentation on the material

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14
Q

The resistant to wear of the composite resins to abrasion depends on what?

A

the nature of the filler particles(glass or quartz) and on silanation of the filler

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15
Q

How many more times is enamel resistant to abrasion than dentin?

A

5 to 20

cementum is the least resistant to abrasion

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16
Q

After how long can prophylaxis fluoride be removed?

A

30 seconds

17
Q

how much enamel can be removed due to abrasion

A

0.6 to 4 micrometers

18
Q

what is working time

A

time after which the material cannot be manipulated without creating distortion in the final product

19
Q

final setting time?

A

the time at which a material can be withdrawn without distortion or tearing.
eg. alginate

20
Q

initial setting time

A

the time at which a certain arbitrary stage of firmness is reached in the setting process

21
Q

Dynamic mechanical analysis

A

allows us to predict the strength and structure of the tested materials and applicability in the clinical setting

22
Q

what is rheology

A

the study of deformation and flow of materials

23
Q

What does the differential scanning calorimetry tool do?

A

determines temperature transitions in materials

eg. glass transition temperature and melting temperature

24
Q

Spectrometric technique

A

Fourier-transformed infrared (FTIR) spectroscopy is used for molecular characterization and for following chemical reactions

25
Q

Pycnometry

A

a technique used to determine material density

26
Q

Bond strength test methods

macroshear

A

typical dentin bond strength values are 10-50 MPa. Cohesive and mixed failure 55% of specimens

27
Q

Bond strength test methods

macrotensile

A

typical bond strength values are 10 MPa. Cohesive and mixed failure 35% of specimens

28
Q

Bond strength test methods

Microtensile

A

typical bond strength values are 30-50 MPa. Cohesive and mixed failure less than 20% of specimens

29
Q

Bond strength test methods

Microshear

A

typical bond strength values are 20 MPa. Cohesive and mixed failure 50% of specimens

30
Q

Polymerization Stress Test

A

was developed to evaluate the stresses developed at the bonded interface due to resin composite polymerization while bonded to cavity walls.

31
Q

What are the two committees that have to pass a product?

A

American National Standards Institute (ANSI)
American Association Standards Committee of Dental Products
Then approval is reviewed by the Council of scientific affairs of the ADA

32
Q

What is the program for international specifications?

A

FDI World Dental Federation and the International Organization for Standardization (ISO)

Dental Materials (7 decks)

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