Layers Dentin

Question 1

Which is the must abundant tissue in the oral cavity and what’s mechanical and optical function ?

Answer 1

Dentin
Provide elasticity , resistant to dental complex .
Highly flurecent tissue due to photochrome ( protein)

Question 2

What’s dentin color ?

Answer 2

Reddish-yelllow
High chroma and opacity

Question 3

What’s primary and secondary dentin ?

Answer 3

Primary since formation of tooth germ
Secondary at the moment of contact opposing teeth continue through life

Question 4

Along the tooth structure describe the differences between dentin saturation and chromacity :

Answer 4

Center of tooth more chromatic
Close to surface become less saturated
A2 tooth , bear pulp A3

Deep dentin become closer too pulp , pulp located more cervically so in cervical area chromacity and opacity are more ( where the tooth is thicker )
As we go incisally chroma decrease

Question 5

What’s happen to dentin color with aging ?

Answer 5

Slow increase in red-orange component of tooth , become more chromatic .

Question 6

Why does dentin changes color by time that make the transition from originally white opaque dentin to darker and more translucent ?

• there is thickness changes + color both related to

Answer 6

1. By decreased pulp size that get replaced by apposition of secondary dentin & sclerosis of dentinal tubules making it less permeable .
2. Hydration of tooth and addition of pigments to dentin structure ( more hydration = more dark (low value) for both dentin and enamel ) .
3. Mineralization , let dentin loss opacity over the time and become more transparent ( min process near DEJ ).
4. Physiological wear of enamel makes dentin more visible

Question 7

What’s the relation between mineralization and chroma and permeability and chroma ?

Answer 7

Explain from sour sea

Question 8

Does the dentin only opaque ?

Answer 8

No it’s also translucent cause it contain its organic and non organic parts

Question 9

When we restore small restoration in which translucency level of material we will interast ?

Answer 9

Small resto means that healthy surround tooth structure will be present to choose more translucent material to display and reflect the underlying tooth structure .

Question 10

When we restore large restoration in which translucency level of material we will interast ?

Answer 10

Opaque material for build up , cause if it translucent it would be unable to mask the black ground of oral cavity .

Question 11

What’s the thickness of 1mm human dentin and enamel and composite ?

Answer 11

Human : 16.4 & 18.4
Composite : 6.3 & 17.2

Higher numbers for translucency
Opaque is 0.0

Question 12

What’s young teeth dentin chroma , enamel value ?

Answer 12

Low chroma
High value

The value of enamel hides the dentin and increase tooth value.

Question 13

What’s adult teeth dentin chroma , enamel value ?

Answer 13

Chroma : moderate
Value : medium

Enamel is slightly increase tooth value

Question 14

What’s old teeth dentin chroma , enamel value ?

Answer 14

Chroma : high
Value : low

Enamel increase tooth value very little

Question 15

What’s cooperation between chroma and value ?

Answer 15

Chroma for dentin as it increase it will decrease value ( tooth brightness )
There is several factors the affect the enamel by age which leading to enamel loss or discoloration decreasing it value and increase chroma
Or by increasing the chroma the value decrease

So as we grow chroma grow , less years remain mean less value

Question 16

Explain dentin elasticity and how give it strength

Answer 16

Dentin the most resistant human tissue , but not the hardest ( it’s related to high elasticity ) and responsible for enamel support and pulp protection .

In absence of dentin enamel can’t withstand cause its substrate .

Its has resistance to traction , compression , shear forces .

Enamel and dentin they are different composite when we need dentin replace it by dentin .

Question 17

Explain dentin elasticity and how give it strength

Answer 17

Dentin the most resistant human tissue , but not the hardest ( it’s related to high elasticity ) and responsible for enamel support and pulp protection .

In absence of dentin enamel can’t withstand cause its substrate .

Its has resistance to traction , compression , shear forces .

Enamel and dentin they are different composite when we need dentin replace it by dentin .

Question 18

Large percentage of light that hits the dentin is reflected back , this light returned with more energy than original what’s explain these ?

Answer 18

Fluorescent of tissue that posses photochrome and fluorophore

Question 19

What’s the must fluorescence part of our body ?

Answer 19

Dentin layer and it’s proteins that bind to the enamel the most in our body , even enamel fluorescence is in less degree .

Question 20

Under which type of light fluorescence is evident , how it appear under natural light ?

Answer 20

Evedent under fluorescent light , but can seen but less obviously under natural light .
Cause some invisible light is bounced back from the teeth with higher energy (visible light ) it impair ( ينعم ينعش) vitality of natural teeth.

Question 21

What does. Lack of fluorescence mean ?

Answer 21

Devitalized teeth
Pathological condition
Prosthetic teeth

Question 22

There is some thing called fluorescent material ?

Answer 22

Yes , any resto material lack it not considered to be an optimal esthetic material .

Question 23

In Endo teeth what’s the considerations in layering ?

Answer 23

These teeth lost fluorescent , so is appropriate to restore some layers of these teeth with more fluorescent material than would normally be used.

Question 24

What’s inner glow ?

Answer 24

The vital appearance of teeth due to fluorescence that light emission from inside .

Question 25

Does dark chroma has high fluorescence ?

Answer 25

No the lighter the chroma the more fluorescent the material becomes

Question 26

How ages decrease fluorescence of dentin , how it also noticed on old composite ?

Answer 26

Protein loss , tissue meneralization , pigmentation .
Aged Composite also lose fluorescence but slightly .

Question 27

What’s DEJ ?

Answer 27

Thin layer consitututed of partially mineralized collagen protein fiber bundles that penetrate enamel and dentin .

Question 28

What’s DEJ function optically ?

Answer 28

To increase fluorescence and natural appearance , increase value .

Highly fluorescent layer , very high value ( white ) , highly translucent at same time .
Acts as light transmitter and scatter toward the dentin provide appearance of depth and vitality .

Question 29

What’s DEJ function mechanically ?

Answer 29

Shock absorber against stress forces
Prevent propagation of fractures into the enamel

Question 30

How DEJ provide appearance of depth and vitality OF TEETH ?

Answer 30

Acts as light transmitter and scatter toward the dentin

Question 31

Does DEJ must be produced ?

Answer 31

Yes between enamel and dentin ( glass connnector enamel plus HFO , micerium , DE connector , ultra dent ).

Nowdays doesn’t require to reproduce cause modern composite have there high fluorescence .

Question 32

About what fluorescence depends on does it UV light or any kind of light or material thickness ?

Answer 32

No it depends on photochemistry , sometimes like jellyfish we can see fluorescence in UV .

Question 33

How devitalized tooth loss their fluorescence ?

Answer 33

Dehydration , loss of internal dentin value ( Carie’s , access cavity ) , break down of proteins by chemicals such as sodium hypochlorite .

Question 34

Devital teeth , Endo teeth does DEJ has to be produced ?

Answer 34

This teeth need. Fluoresnce more than others .
It’s important to restore them with the inside layer DEJ , that serve as a source of luminous energy to recover value and fluorescence .

In Endo teeth restored with non fluorescent , or semi fluorescent will have non vital appearance .

Question 35

Does highly fluorescent layer enough to restore Endo treated teeth ?

Answer 35

No also use high fluorescent dentin and if post needed should be highly fluorescent as well .

Question 36

Where does the highly fluorescent dentin found in?

Answer 36

Surround pulp
It’s why Endo is probomatic

Question 37

What’s happen to dentin fluresnce after enamel placemat ?

Answer 37

Decrease

Question 38

Explain light scattering and its relation with tooth structure components ?

Answer 38

Dissemination (انتشار) of light into the dentinal results from the interaction between inorganic and organic matter.

For example : hydoxyapatitie is transparent and collagen is opaque
Tubules are full of fluid and proteins , that make light alter the trajectory ( مسار ) when passing through this structure .

Question 39

Opacity of dentin vary along tooth this depend on what ?

Answer 39

On the area and arrangement of dentin