Enamel

Question 1

describe features of enamel?

Answer 1

hardest tissue in body
resists abrasion
brittle
supported by dentine
covers tooth crown
translucent
transparency increases with mineralisation

Question 2

what is abrasion of tooth?

Answer 2

based on physical contact
- physiological wear of tooth

Question 3

what is attrition of tooth?

Answer 3

pathological wear of tooth
(grinding)

Question 4

what supports enamel to make it less brittle?

Answer 4

dentine
will chip if unsupported

Question 5

enamel varies in thickness. explain

Answer 5

thicker at inscisal edge
ocluso plate of molars is thicker than incised edge for function

Question 6

describe the transparency and translucency of the tooth?

Answer 6

transparency = see through
translucency = light can pass through but not see through

Question 7

where does the colour of teeth come from?

Answer 7

dentine

Question 8

what happens when a tooth is developing?

Answer 8

starts soft and becomes hard while it takes shape (matrix formation)

Question 9

what is the space between tooth and gum called?

Answer 9

vestibule

Question 10

how are teeth formed?

Answer 10

buds positioned where they are going to erupt

Question 11

how many deciduous teeth and how many permanent teeth?

Answer 11

20 and 32

Question 12

2 features of deciduous

Question 13

2 features of deciduous teeth.

Answer 13

already completely formed
no molars

Question 14

when is crystallite orientation determined?
what is the orientation?

Answer 14

-during enamel formation
-some are parallel and some perpendicular to the enamel rod

Question 15

how are crystallites in enamel positioned with the ameloblast membrane?

Answer 15

at right angles

Question 16

what makes the template of crystallites?

Answer 16

ameloblasts

Question 17

what tooth has wider roots? permanent or deciduous?
and why?

Answer 17

deciduous because permanent tooth is under it

Question 18

where is the enamel more mineralised and harder in the tooth?

Answer 18

at the surface
- hardness decreases from cusp tip/ incised edge to cervical region

Question 19

as tooth is in mouth for long period of time does it become more or less mineralised?

Answer 19

more mineralised

Question 20

what is the enamel rod (prism)?

Answer 20

basic unit

Question 21

where do rods run?

Answer 21

amelo-dentinal junction to surface

Question 22

what do rods contain?

Answer 22

Hydroxyapatite crystals

Question 23

how does the orientation of a rod vary?

Answer 23

within and along the rod

Question 24

what is the content of enamel? (%weight and %volume)

Answer 24

Hydroxyapatite 95% and 90%
water 4% and 5-10%
organic matrix 1% and 1/2%

Question 25

what does the organic matrix is enamel contain?

Answer 25

proteins, amelogenins
enamelling, peptides and amino acids

Question 26

what does the organic matrix is enamel contain?

Answer 26

proteins, amelogenins
enamelling, peptides and amino acids

Question 27

what is the shape of a HA crystal?

Answer 27

spiral

Question 28

describe the enamel surface?

Answer 28

smooth
has pits and fissures

Question 29

what is a fissure?

Answer 29

valley on the tooth
upper lateral