enamel development and function :)

Question 1

what is enamel derived from

Answer 1

ectodermal enamel organ

Question 2

what does enamel form

Answer 2

surface layer of anatomical crown

Question 3

minerlisation of enamel

Answer 3

96%

Question 4

what cells form enamel

Answer 4

ameloblasts

Question 5

what do ameloblasts come from

Answer 5

differentiate from the interla dental epithelium starting from the uppermost part

Question 6

what causes a signal to be sent to the IDE to differentiate into ameloblasts

Answer 6

dental papillary cells form odontoblasts

secrete dentine and signal is sent

Question 7

what forms first dentine or enamel

Answer 7

dentien

Question 8

what induces the differentiaion of IDE into emeloblasts

Answer 8

BMPs

secreted by odontoblasts into dentine matrix

Question 9

how do ameloblasts deposit enamel

Answer 9

from secretory end
move in an S shape
absorb protiens from enamel as it is mineralised

Question 10

phases of enamel formation

Answer 10

secretory
transition
maturation

Question 11

what % is mineralised when it is first secreted

Answer 11

30%

Question 12

what happens in the maturation phase

Answer 12

organic material is removed

Question 13

what happens in the transition phase

Answer 13

increased mineral content from30 to 96%

secretion of amelogenin

Question 14

how is the enamel deposited initially

Answer 14

prismatic

adjacent to the ADJ

Question 15

what happens during secretion of enamel steps

Answer 15

ameloblasts produce a pyrmatidal tomes process

HAP crystals are laid down at right angles to the cell surface (from to apex)

Question 16

where are rod boundaries

Answer 16

coincide with tomes process apex

Question 17

how do rod boundaries happen

Answer 17

HAP crystals are laid down at right angles to the cell surface so either side is opposite rods

Question 18

enamel maturaltion

Answer 18

crystals get thicker as the enamel becomes more mineralised

Question 19

enamel structure

Answer 19

keyhole shape - interlock to strength enamel

rods run parallel in layers

Question 20

what does the enamel structure have

Answer 20

shallow sinusoidal curvature

Question 21

what occurs during enamel formation

Answer 21

amelogenins are withdrawn and destroyed by enamelysins
enamelins left
space vacated is replaced by water
HAP grow in thickness displacing water

Question 22

what does fluoride to

Answer 22

strengthen enamel

Question 23

what can protein do to enamel if not removed

Answer 23

developmental defect

protein inhibit mineralisation by preventing crystal crystal fusion

Question 24

what is the reduced enamel epithelium

Answer 24

amelobalsts and EDE?

protects the enamel and forms part of the gingiva

Question 25

what are examples of defects of enamel development

Answer 25

``` hypoplasia hypominerlisation amelogensis imperfecta fluoride induced opacity intrinsic discolouration ```

Question 26

what is hypoplasia

Answer 26

thinner layer of enamel on crown

Question 27

what is hypominerlisation

Answer 27

less mineralised | occurs in maturation stage

Question 28

what is amelogensis imperfect

Answer 28

abnormalities in genes involved in enamel formation

Question 29

what does too much fluoride cause

Answer 29

less mineralisation as it affects protein degredation

Question 30

what cannot be presribed to pregnant women

Answer 30

tetracyclines | caused discoloured enamel to foetus

Question 31

what are optical artefacts of enamel

Answer 31

interference and diffraction(interaction and bending) | reflection and refraction(speed changes)

Question 32

where do enamel rods run

Answer 32

from ADJ to outer surface | in adjacent layers offset abut 2degress from eahc other

Question 33

what desgin features of enamel give strength

Answer 33

offset of enamel rods | keyhole shape

Question 34

what is enamel supported by

Answer 34

dentine and PDL

Question 35

what does the PDL do

Answer 35

absorbs masticatory loads

Question 36

properties of dentine

Answer 36

high tensile and compressional strenght

Question 37

how does enamel form

Answer 37

in increments | brown striae and dailty incrememtal lines

Question 38

what is the neonatal line

Answer 38

exaggerated incremental line in teeth mineralising at birhtas ameloblasts pause their activity

Question 39

what teeth have the neonatal line

Answer 39

the developing teeth at birth ie 6's

Question 40

what are enamle spindles

Answer 40

at ADJ | odontoblasts get trapped within the enamel

Question 41

what are enamel tufts

Answer 41

found at ADJ in transverse section | areas of hypomineralised rods

Question 42

what are enamel lamallae

Answer 42

cracks that run through enamel following lines of prism orientation may cause the tooth to fracture

Question 43

what happens once enamel is fomed

Answer 43

it cannot be reparied as the ameloblasts die

Question 44

how can remineralisation occur

Answer 44

saliva contains calcium and phosphate (ion exchange)

Question 45

how do carious lesions appear initially

Answer 45

white spots

Question 46

what is topical fluride

Answer 46

exchange of fluride for hydroxl ions in apatite crystals

Question 47

what type of surface will restorative materials adhere to and how is this done

Answer 47

roughened surface 'acid etch' applying acid to enamel surface and then washing off

Question 48

what does fluride do to calcified material

Answer 48

will decrease its acid solubility

Question 49

how can fluide be appliec

Answer 49

topically | systemically

Question 50

what can be seen in ground sections

Answer 50

``` brown striae(like tree trunk circle lines) light interfernece lines ```

Question 51

what forms the reduced enamel epithelium

Answer 51

the enamel organ reduces in thickness and forms the REE

Question 52

what provides nutrients for amelobalsts

Answer 52

stellate reticulum

Question 53

what is the matrix of enamel in the secretory phase

Answer 53

matrix consists of amelogenin and enamelin proteins ratio 20:1