Loading presentation...

Present Remotely

Send the link below via email or IM

Copy

Present to your audience

Start remote presentation

  • Invited audience members will follow you as you navigate and present
  • People invited to a presentation do not need a Prezi account
  • This link expires 10 minutes after you close the presentation
  • A maximum of 30 users can follow your presentation
  • Learn more about this feature in our knowledge base article

Do you really want to delete this prezi?

Neither you, nor the coeditors you shared it with will be able to recover it again.

DeleteCancel

Make your likes visible on Facebook?

Connect your Facebook account to Prezi and let your likes appear on your timeline.
You can change this under Settings & Account at any time.

No, thanks

The development of cementum

No description
by

Afeef Zaqout

on 30 April 2014

Comments (0)

Please log in to add your comment.

Report abuse

Transcript of The development of cementum

Contents:
Cementum
Cementum is a hard, a vascular connective tissue that covers the roots of teeth.

Cementum
It begin from CEJ continues to apical foramen , that cover the dentin in the root portion .

The thickest part is at the root apex and in the inter-radicular areas of multirooted teeth (50-200um) .

Thinnest at the CEJ (10-50um).

Cementum is considered One of components of periodontium
The development of cementum

Hard Tissue Of Teeth
Oral Histology
Introduction
Structure of cementum .
Function & Properties of cementum
Tooth Develpoment
Root Formation
Cementogenesis .
Type Of Cementum .
Incremental line of salter
the Pathology

Properties of cementum
Hardness is less than that of dentin

Chemical Composition
45-50 % Inorganic substances

Hydroxyapatite crystals

50-55% Organic substances & water

Collagen
protein
Polysaccharides
Trace elements

Cementum contains the greatest amount of fluoride in all mineralized tissues

Function of cementum
attachment site for the periodontal ligament.
Protects the underneath tissues.
the loss of cementum will expose dentin to the oral environment.
Assists in maintaining the length and width of periodontal ligament space by apposition of new cementum.
Assists in repairing fractures by restoration of the root by apposition of new cementum.

Tooth development

Root Formation & Cementogenesis
the Cervical lobe begins to grow down into the dental sac –elongates and moves away from the dental papilla

it forms a Hertwig's root sheath
Types Of Cementum
1-By the location
 Radicular cementum:
The cementum that is found on the root surface







2- By cellularity
   Cellular cementum:
Cementum containing cementocytes in lacunae within the cementum matrix.

3- by presence of collagen fibrils 
 Fibrillar cementum:  
Cementum with a matrix that contains well-defined fibrils of type I collagen.


 Afibrillar cementum: 
Cementum that has a matrix devoid of detectable type I collagen fibrils. .


4- By the origin of the matrix fibers
The collagen fibrils of cementum are of three kinds:
extrinsic group ( sharpey's fibers ).
intrinsic group.
Mixed group.

are formed by the cementoblasts
It generally corresponds to secondary cellular cementum
found between the sharpey's fibers.

Intrinsic fibre cementum
Its is derived as Sharpey’s fibres .
They are formed by the fibroblasts of the periodontal ligament
This type of cementum corresponds with primary cementum

Extrinsic fibre cementum
Mixed Fiber
the collagen fibres of the organic matrix are derived from both extrinsic fibres and intrinsic fibres

Not :
There is another classification

Acellular extrinsic fibre cementum
Cellular intrinsic fibre cementum
Acellular Afibrilar cementum
Incremental lines of Salter
The appearance of incremental lines in cementum is mainly due to differences in the degree of mineralization, but these must also reflect differences in composition of the underlying matrix


Cemento-dentinal junction
The dentin surface upon which cementum is deposited is relatively smooth in permanent teeth.


The cementodentinal junction in deciduous teeth, however, is sometimes scalloped

Cemento-Enamel Junction

Cemento-Enamel Junction

In about 10% of the teeth, enamel and cementum do not meet.

In approximately 30% of all teeth, cementum meets the cervical end of enamel in a relatively sharp line.

In approximately 60% of the teeth, cementum overlaps the cervical end of enamel for a short distance.

Pathology of cementum
Root resorption :
in the apical portion of the root may occur, however, if orthodontic pressures are excessive and movement is too fast

Pathology of cementum
Hypercementosis
The excessive build up of cementum on the roots of a tooth
Pathology of cementum
Cemental Caries :
 it increases in older adults as gingival recession occurs from either trauma or periodontal disease
Pathology of cementum
Cementilcle :
 are mineralized bodies of cementum found either attached to the cemental root surface or lying free in the periodontal ligament .
Pathology of cementum
Ankylosis : is the fusion of cementum and alveolar bone with obliteration of the periodental ligament

epithelial diaphragm–encloses the developing primary apical foramen


The function of this sheath is determination of the root shape


Cementum formation in the developing tooth is show by the deposition of dentin along the inner aspect of Hertwig‘s sheath .

the undifferentiated mesenchymal cells derived from the dental sac differentiate into cementoblasts .

These cells have the ultrastructural characteristics typical of cells actively synthesis protein and polysaccharide .








Growth of cementum is a rhythmic process and as a new cementoid is formed, the old one is calcified .

A thin layer of cementoid can be observed on cemental surface which is covered by cementoblasts .

cementoid :the cementum matrix produced by the cementoblasts

The mineralization begins after forming the first layer of matrix.



During matrix formation fibroblasts form collagen fibers (sharpey`s fibers), which become embedded in the matrix to provide attachment of the root to the surrounding bone.

cementoblasts become entrapped in the forming matrix and then known cementocytes .

Cementocytes

Cementocytes are seen located in lacunae in cementum matrix and typically have numerous processes lying in canaliculi .

References
Oral Anatomy, Histology And Embryology Book
(Ten Cate 8th Edition )
Wikipedia

Light yellow in color
Semi-permeable to variety of material
Can be distinguished from enamel by it’s lack of luster and it’s darker hue.
Properties of cementum
Properties of cementum
Properties of cementum
cementogenesis
cementogenesis
Matrix formation

Mineralization
Collagen fiber type I

Ground substance

Hydroxy apatite crystals

There are 3 cell types responsible for the cementogenesis:
Cementoblasts
Cementocytes
Fibroblasts

Cementogenesis

Cementum formation in the developing tooth is shown by deposition of dentin along the inner aspect of Hertwig‘s sheath .
the undifferentiated mesenchymal cells derived from the dental sac differentiate into cementoblasts

Growth of cementum is a rhythmic process and as a new cementoid is formed, the old one is calcified .

A thin layer of cementoid can be observed on cemental surface which is covered by cementoblasts .

cementoid :the cementum matrix produced by the cementoblasts

The mineralization begins after forming the first layer of matrix.

Coronal cementum: 
The cementum that forms on the enamel covering the crown
Acellular cementum:
Cementum without any cells in its matrix
The Types of Cementum
Root Formation & Cementogenesis
Full transcript