6 mandible dr sherif hassan
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MANDIBLE
د شريف حسن 1
ORIGIN OF THE MANDIBLEFirst Branchial Arch
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TYPES OF OSSIFICATION
1- INTRAMEMBRANOUS
2- ENDOCHONDRAL
FLAT BONES LONG BONES
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* Starts at : 6 WIU* Develops: Intramembranous ossification* Site of ossification center of the mandible:At branching of mental and incisive from inferior alveolar nerve.•Gives rise to: 1. Body of the mandible.2. Ramus of the mandible under the inferior alveolar canal.
Development Of Body Of The Mandible
Ossification Center
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DEVELOPMENT OF CONDYLE
Time of origin: 14 WIU. ❑ Site: Condylar head. ❑ Life span: Continue until 20 years of age. ❑ Type of ossification: Endochondral type. ❑ Gives rise to: 1- Head and neck of condyle. 2- Posterior part of ramus above mandibular foramen.
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DEVELOPMENT OF CORONOID
Time of origin: 4 MIU. ❑ Site: Anterior border of Coronoid. ❑ Life span: Continue until first years of age. ❑ Type of ossification: Endochondral type. ❑ Gives rise to: 1- Coronoid process. 2- Anterior part of ramus above mandibular foramen.
DEVELOPMENT OF SYMPHYSIS
❑Site: At the midline of the mandible. ❑Life span: Continue until first year of age. ❑Type of ossification: Endochondral type. ❑Gives rise to: 1- Symphysis menti. 2- Increase the width of the mandible.
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❑ Condylar growth leads to:
1- Increase Ramus Height.
2- Increase Mandible’s Length.
3- Increase Inter-condylar Distance.
* Growth of the mandible is obtained by the following:
1.Growth by condylar cartilage.
2.Development of alveolar process and tooth eruption.
3.Subperiosteal bone deposition and resorption
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❑ Growth of Alveolar Process:1. Increase height Of Alveolar Process. 2.Increase height Of The Body of mandible.
❑ Growth by Subperiosteal Bone Deposition and Resorption: 1. Increase The Body Length and Height. 2. Widening Of The Mandible. 3. Increase The Distance Between Mandibular Canal And Roots.
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** IMPORTANT NOTE **
Growth Of Condyle ceased At :
20-25 Years Of Age.
Growth Of Lower Border Of Mandible Stopped At :
7 Years Of Age.
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AGE CHANGES OF THE MANDIBLE
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AGE CHANGES OF THE MANDIBLE
Stages of growth: 1. At birth. 2. Child. 3. Adult. 4. Old age after teeth extraction.
Study point: 1. Angle of the mandible. 2. Condyloid and coronoid processes. 3. Mental foramen level. 4. Tooth number.
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AT BIRTH:1. Angle of the mandible: 165o
2. Coronoid process: at higher
level in relation to condyle.
3. Mental foramen: at lower level
4. Deciduous teeth: no teeth.
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CHILD: 1. Angle of the mandible: 140o
2. Coronoid process: at higher level in
relation to condyle.
3. Mental foramen: at higher level than in
infant but not reach to the middle of the
vertical height
4. Deciduous teeth: fully erupted
5. The condyle: contain cartilage for growth.
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ADULT:1. Angle of the mandible: 110o
2. Coronoid process: at lower level in
relation to condyle.
3. Mental foramen: above the level of
middle of the vertical height
4. Permanent teeth: fully erupted and
alveolar bone are fully developed.
5. The condyle: contain cartilage for
growth until the second decade ( 20 year).16
OLD AGE:1. Angle of the mandible: 140o
2. Coronoid process: at higher
level in relation to condyle.
3. Mental foramen: become near
the upper border of the mandible.
4. Permanent teeth: are extracted
with alveolar bone degeneration.
5. The condyle: not contain
cartilage.17
THANK YOU
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