Lecture 3

Question 1

Rheology

Answer 1

the study of how matter flows and its characteristics

Question 2

viscosity

Answer 2

resistance to motion of a liquid controlled by internal friction forces within the liquid
(low - water, high - hard)

Question 3

thixotropic

Answer 3

a liquid that become less viscous and more fluid under pressure (squeezing ketchup)

Question 4

creep

Answer 4

time-dependent plastic strain of material under constant pressure
(pressure dependent)
(glass window flowing down)

Question 5

sag

Answer 5

deformation potential of long span metal bridges during porcelain firing
(temperature-dependent)

Question 6

amorphous material

Answer 6

wax
does not have crystalline structure -> super cooled liquid
FLOW is used to describe deformation in such material

Question 7

rate of heat flow

Answer 7

dependent on area and temperature gradient across the structure.

Question 8

dentin as insulator

Answer 8

dentin is good insulater when its thick. When it thins place something that insulates.

Question 9

insulator

Answer 9

material with low thermal conductivity

Question 10

thermal diffusivity

Answer 10

controls the time rate of temperature change as heat passes through a material.

Question 11

coefficient of thermal expansion

Answer 11

change in length per unit of original length of material when temperature is raised be 1’C
(material should hv similar coefficient as tooth)

Question 12

resin

Answer 12

first layer on top of dentin to connect tooth to composite

Question 13

replacement of dentin or enamel

Answer 13

replace with composite or porcelain

Question 14

value

Answer 14

relative blackness or whiteness

o = white, 100 = black

Question 15

hue

Answer 15

basic color dominant wavelenth

basic color’s wavelenght

Question 16

chroma

Answer 16

brightess, intensity of color

Question 17

cone

Answer 17

color

Question 18

rod

Answer 18

light intesnsity

Question 19

ceramics

Answer 19

light penetrates and refracts

Question 20

metaerism

Answer 20

color looks different in other light

Question 21

fluorescence

Answer 21

object that absorb lights and convert them into longer wavelenth

Question 22

dentin vs enamel

Answer 22

Young’s modulus and Hardness number much lower in dentin

tensile strength higher on dentin

Question 23

strongest tooth

Answer 23

mesial buccal cusp

Question 24

materials used

Answer 24

plastic
metallic
ceramic

Question 25

hardness

Answer 25

ability of material to resist abrasion or wear

can only be compared between similar materials