dentin ^_^
Post on 02-Jul-2015
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DENTINDentin
Dentin is a crystalline material that enclose the pulp , formed by odontoblast and it is mesenchymal in origin.Dentin is coverd by enamel on the chrown and cementum on the root.
Dentin is the most voluminous mineralized conective tissue of the tooth.Forms the hard tissue portion of the dentino-pulp complex.
COMPOSITION
Hard tissue forming the bulk of the tooth.
Softer than enamel but harder than bone and cementum.
It has a yellow color.It has a rough surface texture
than the enamel.
PHYSICAL PROPERTIES
Vital and has nerve fibers but avascular.
Less dense than enamel on radiograph and appear radiolucent.
It is permeable.
Has elastic quality.
PHYSICAL PROPERTIES
1. DENTINAL TUBULES A long tubule extend from DEJ in
the crown or DCJ in the root to outer wall of the pulp.
Follow a gentle ,S, -shaped curve in the tooth crown and are straight in the incisal edges, cusps and root areas.COMPONENTS OF DENTINAL TUBULEa. Odontoblastic cytoplasmic process.b. Dentinal fluid. c. Nerve fibers.
BASIC COMPONENTS
{
Dentinal tubules
Cross section
Longitudinal section
2. PERITUBULAR DENTIN
Immediately surround and forms the wall of detinaltubules
More highly calcified than intertubular dentin
3.INTERTUBULAR DENTIN
-Is the dentin found
between the peritubulardentin and it forms the most bulk of dentin.
BASIC COMPONENTS
PRIMARY DENTIN
Formed before root completion.
Formed by primary odontoblast.
Formed in faster rate.
Gives initial shape of the tooth.
It continues to grow till 3 years after tooth eruption.
It is more permeability.
a. Mantle dentin.
b. Circumpulpal dentin
TYPES OF DENTIN
{Circumpulpal dentin
Irregular Secondary dentin
Secondary dentin
Predentin
Mentledentin
Primary dentin
SECONDARY DENTIN (Regular secondary dentin) Formed after completion of root formation. Formed at a slower rate than primary dentin. Thickness increase with advacing age. Formed by primary odontoblast. Less permeability.
TERTIARY DENTINKnown as (Irregular secondary or Reparative or sclerotic dentin) -Frequently formed as a response to external
stimuli such as (dental caries, attrition). -Formed only at the site of odontoblast activation. Formed by secondary odontoblast. Thickness increase with advacing age. The least permeability of dentin, therefore
helping in prevention of diffusion of noxious agent from the tubules.
1. Protection of the pulp.
2. Affects the color of enamel.
3. Shoch absorber and prevent fracture of enamel.
4. Determine the shap of the crown.
FUNCTIONS OF DENTIN
1. Imbrication line of Von Ebner,s
2. Counter line of Owen
3. DEJ
4.CEJ
5.Neonatal line
6.Tome,s granular layers
7.Interglobular dentin
8.Age changes
Microscopic feature Of Dentin
{
Lines of Owen Neonatal line
{
Incremental lines
{
Tomes granular layer
Tomes granular layer
Age changes
sclerotic dentin
Dead tract
1. As dentin is known to provide strength and rigidity to the tooth,care should be taken during tooth preparation.
2. Tooth preparation should be done under constant air water spray to avoid build up of heat formation.
CLINICAL CONSIDERATION OF DENTIN
3. Dentin should always be protected by liners,bases or dentin bonding agents.
4. Smear layer is formed as a result of tooth cutting(quantities of cutting debris) for bonding of restorative materials to tooth structue,this smear layer has to be removed by etching process.
.
CLINICAL CONSIDERATION OF
DENTIN
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