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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