Development of mandible

1. Development of
Mandible
Presented by
Dr. Shweta Yadav
(Junior Resident)
Guided by
Dr. Kshitij Bang
(Asso.Prof. & Guide)
Guided by
Dr. S.R.Shenoi
(Prof. & HOD)
Department of Oral & Maxillofacial Surgery
VSPM Dental College, Nagpur

2. INTRODUCTION
• Mandible – Largest and Strongest bone of the face
• Greek word ‘mandere’- to masticate
• Latin word ‘mandibula’-lower jaw

3. History and Background
• JOHN HUNTER (1771) compared a series of dried mandibles and
concluded that to attain space for permanent molar teeth the mandible
must grow by posterior apposition of ramus accompanied by anterior
ramus resorption.
• HUMPHRY (1866) studied growth of mandible by inserting metal
wires in the mandible of young pigs.
• BELCHIE (1936) fed pigs the madder plant root which labeled
appositional growth

4. • BJORK (1955): conducted implant studies on jaws to determine the
growth pattern & rotation ,when subjected to serial cephalometric
methods.
• DONALD ENLOW : proposed the V principle of growth and
counterpart principle.

5. Prenatal Growth and Development

6. In sixth week ,a single ossification Centre for each half arises in
the bifurcation of inferior alveolar nerve into mental and incisive
7th week-bone begin to develop lateral to Meckels cartilage and
continues until the posterior aspect is covered with bone
Between 8th & 12th week ,mandibular growth accelerate ,as a
result mandibular length increases

7. Ossification stops at a point , which later become lingula , the
remaining part of meckels cartilage continues to form
sphenomandibular ligament & spinous process of sphenoid
Secondary accessory cartilage appears between 10th & 14th week
to form head of condyle , part of coronoid process & mental
protuberance

8. SECONDARY CARTILAGES IN
MANDIBULAR DEVELOPMENT
CONDYLAR PROCESS
• About 5th week of I.U.L. area of mesenchymal
condensation above the ventral part of developing
mandible
• About 10th week develops into cone shaped cartilage
• By 14th week starts ossification
• By 4 months migrates inferiorly and fuses with ramus
• 4th month onwards replaced by bone but proximal end
persists into adulthood acting as Growth cartilage &
Articular cartilage

9. CORONOID PROCESS
• By 10th to 14th week of I.U.L. secondary cartilages seen in region
of coronoid
• Cartilage becomes incorporated into expanding intramembranous
bone of ramus and disappears before birth
MENTAL REGION
• Secondary cartilages seen on both sides -- ossify by 7th week
I.U.L.
• They ossify to form mental ossicles in fibrous tissue of
symphysis.

10. Postnatal Growth and Development
MANDIBLE AT BIRTH
• Ascending ramus- low and wide
• Coronoid process- relatively large
• Body – containing buds and partial crowns
of deciduous teeth
• Mandibular canal- runs low in the body

11. MANDIBULAR GROWTH DURING FIRST
YEAR
Appositional growth especially active at
• Alveolar border
• Distal and superior surface of ramus
• Condyle
• Lower border of mandible
• Lateral surface of mandible
By the end of first year mandible appears
as a single bone.

12. GROWTH PROGRESSION AFTER FIRST
YEAR- MECHANISM & SITE
Ramal remodeling is important
1. Positions the lower arch in co-ordination with
the growth of upper arch
2. Adaptive to changing cranio facial conditions
Hunterian Concept
• The principal vectors of mandibular growth are
posterior and superior
• Mandible as a whole becomes displaced
antero-inferiorly.

13. MANDIBULAR FORAMEN
• Relocates backward and upward
by deposition on the anterior and
resorption from the posterior part of
the rim
• From childhood throughout the old
age maintains a constant position
about midway between the anterior
and posterior borders of the ramus.

14. RAMUS TO BODY REMODELING CONVERSION
In general the arch length is increased
and body has been lengthened by
1. Deposits on the posterior surface of
lingual tuberosity and the contiguous
lingual side of ramus
2. A resultant lingual shift of anterior part
of the ramus to become added to the
body

15. Condyle and mandibular growth

16. Theories of mandibular growth
GENETIC THEORY: states that all growth is compelled by genetic
influence ie: genetic encoding of mandible determines its growth.
CARTILAGENOUS THEORY: states that the cartilage is the primary
determinant of skeletal growth while bone responds secondarily & passively.
ENLOW’S EXPANDING ‘V’ PRINCIPLE: states that many facial bones
or a part of the bone follows a ‘v’ pattern of enlargement.
FUNCTIONAL MATRIX THEORY: mandible as a group of microskeletal
units and a basal core part related to the growth of macroskeletal unit.

17. THANK YOU