Growth and development of mandible /certified fixed orthodontic courses by Indian dental academy

GROWTH AND DEVELOPMENT
OF MANDIBLE

www.indiandentalacademy.com

INDIAN DENTAL ACADEMY
Leader in continuing dental education


CONTENTS









DEFINITIONS
PRENATAL GROWTH
POSTNATAL GROWTH
FACTORS AFFECTING GROWTH
AGE CHANGES IN MANDIBLE
ANOMOLIES IN DEVELOPMENT
MANDIBLE
REFERENCES

What is Growth?







Growth refers to increase in size- Todd
Growth usually refers to an increase in size
and number – Proffit
Self multiplication of living substance –
J.S. Huxley
Entire series of sequential anatomic and
physiologic changes taking place from the
beginning of prenatal life to senility Meridith

What is Development?




It is the progress towards maturity –
Todd
Development refers to all the naturally
occurring unidirectional changes in the life
of an individual from its existence as a
single cell to its elaboration as a
multifunctional unit terminating in death Moyers

•PRENATAL
•POSTNATAL


Prenatal Growth


It’s the most dynamic phase and is divided
as

•Preimplantation period
•Embryonic period
•Fetal period


Formation of the Pharyngeal Arches


The mesoderm of the lateral plate of
the ventral foregut becomes
segmented to form a series of five
distinct bilateral mesenchymal
swelling called as the Pharyngeal
Arches.


th
4www.indiandentalacademy.com
week

4 www.indiandentalacademy.com
week embryo

Contents of each arch






Skeletal element
Striated muscle
Nerve
Artery


Internal view of pharyngeal floor and cut arches

Mandibular Arch






Meckel’s cartilage
Musculature
Mandibular nerve
Artery- maxillary and external carotid


Meckel’s cartilage




41th- 45th day of I.U.L
Provides a template
Extends from Otic capsule –Midline
or Symphysis


Ossification of Meckel’s
cartilage


Mandibular division of trigrminal
nerve

Neurotrophic
factor

Osteogenesis


Ossification of Meckel’s cartilage


In 6th week IU


Trough for dev. teeth
Trough for dev. teeth

1°centre of ossification
1°centre of ossification
below

Infr alv. Nerve &
Infr alv. Nerve &
Incisive branch
Incisive branch

around





Ossification spreads dorsally and
ventrally
•Body
•Ramus
Ossification stops at the site that
will become mandibular lingula

Fate of Meckel’s cartilage









Meckel’s cartilage lacks enzyme phosphatase
It disappears by 24th week of conception
A small part transforms into sphenomandibular and
anterior malleolor ligaments
Ventral end forms accessory endochondral ossicles
Meckel’s cartilage dorsal to mental foramen gets
resorbed on the lateral surface.
Immediately lateral to resorbing
cartilage,intramembranus bony trabeculae are
being formed.


Woven bone
Woven bone
5th month
5th month

Lamellar bone + haversian system
Lamellar bone + haversian system

Coronoid cartilage

Condylar cartilage

10th & 14th week
Sec. accessory
cartilage

Angular cartilage
Mental ossicle




Secondary cartilage of coronoid process



Develop within temporalis muscle





Incorporated into intramembranus bone
of ramus
Disappear before birth







Secondary cartilage at Mental region
1 or 2 small cartilage ossify mental
ossicles(7th month) in fibrous tissue of
symphysis
It gets incorporated into intramembranous
bone
symphysis
menti
1st postnatal year

synostosis
syndesmosis www.indiandentalacademy.com

Condylar cartilage








Serves as a growth site
Brings changes in the mandibular position
and form
Growth increases during puberty
Peak 12 – 14 years
Ceases by 20 years

Types Of Ossification




Mandible is the first bone to be
ossified (6th week)
There are two types of ossification :



INTRAMEMBRANOUS



ENDOCHONDRAL

Intramembranous bone formation
Mesenchyme

Collagen fibre

Osteoblast

Osteoid matrix
Calcium salts

Osteoblasts
Bone lamella

Intramembranous bone
formation


Endochondral bone formation
Mesenchymal cells

Hyaline cartilage
Alkaline
phosphatase

Primary areolae

Calcified
Blood vessels

Secondary areolae

osteoid

Lamella of bone

Endochondral bone
formation


ENDOCHONDRAL


Cartilage template is
replaced by
endochondrial bone

INTRAMEMBRANOUS


Direct deposition of
osseous tissue in
periosteal membrane



Indirect bone growth



Direct bone growt



Slow expansion



Rapid expansion


Parts Of Mandible Derived From
1. INTRAMEMBRANOUS OSSIFICATION
i.

Whole body of mandible except the anterior part

ii. Ramus of mandible as far as mandibular foramen

2 . ENDOCHONDRAL OSSIFICATION
i. Anterior portion of the mandible (symphysis)
ii. Part of ramus above the mandibular foramen
iii. Coronoid process
iv. Condylar process

Neonatal mandible






Ascending Ramus low and wide
Large Coronoid process
Body – open shell containing tooth
buds and partially formed deciduous
teeth
Mandibular canal that runs low in
the body

Neonatal mandible

Differential growth
During fetal life
During fetal life
8 weeks -- mandible > maxilla
8 weeks
mandible > maxilla
11 weeks -- mandible = maxilla
11 weeks
mandible = maxilla
13 – 20 weeks maxilla > mandible
13 – 20 weeks maxilla > mandible
At Birth
At Birth
Mandible tends to be retrognathic
Mandible tends to be retrognathic
Early post natal life -- orthognathic
Early post natal life orthognathic

Post Natal Growth


Mechanism of bone growth



Theories of growth



Anatomy

Mechanisms Of Bone Growth
Growth Of The Mandible Primarily Involve

1. Bone remodeling
Process Of Bone Deposition And Resorption

2. Cortical drift
Combination of bone deposition and resorption resulting in
growth movement towards deposition surface

3. Displacement
Movement of whole bone as a unit

I) Primary displacement
II) Secondary displacement

Theories of growth


Other theories for growth




ENLOW’S “V”
PRINCIPLE
The growth and
enlargement of bones
occur towards wide
end of ‘V’ due to
differential deposition
and resorption

Enlow’s Counterpart
Principle




‘The growth of any given facial or cranial part
relates specifically to other structural and
geometric “counter” parts in the face and
cranium’.
Eg. Maxillary arch is counter part of mandibular
arch.

Regional part
Regional part

counter part
counter part

Balanced growth
Balanced growth


Anatomy


Growth timings




The overall growth of mandible takes
place at different stages.
First there is increase in its
 Width
 Length
 Height

Width






Growth in width is completed before
adolescent growth spurt
Intercanine width does increase after
12 years
Both molar and bicondylar width shows
small increase until growth in length
ends

Growth in length





Growth in length continues through
puberty
Girls - 14-15 years
Boys - 18-19 years


Growth in height




CONTINUES IN BOTH THE SEXES FOR A
LONGER PERIOD
GROWTH INCREASE OCCURS WITH
CONCOMITANT ERUPTION OF TEETH
AND CONTINUES TO INCREASE
THROUGH OUT LIFE AND DECREASES IN
ADULT LIFE


Main sites of post natal growth in the
Mandible


Condylar cartilage



Posterior border of the Rami



Alveolar ridges


Condylar cartilage
Site of growth for ramus and body of mandible
Dual function
articular
articular

growth
growth
Not a primary Centre of growth but rather site of growth
2° in evolution
2° in evolution
2° in embryonic origin
2° in embryonic origin
2°to adaptive changes www.indiandentalacademy.com
2°to adaptive changes

Is the Condylar cartilage the principle
force that produces the displacement of
the mandible ?

For many years considered primary growth
center
Condyle absent yet mandible positioned
normally
Considered secondary cartilage -no intrinsic
growth potential www.indiandentalacademy.com







Condylar cartilage and functioning muscles
translate the mandible and in the absence
of one the other does best to compensate
Integrity of periosteum is important
When environment changes compensatory
contributions are enhanced

Current Concept




Condylar cartilage does have a measure of intrinsic
genetic programming
But extra condylar factors are needed to sustain this
activity
Physiologic
inductors

Intrinsic and extrinsic
biomechanical forces

ENLOW :
Increase pressure – growth inhibition
Decrease pressure – stimulates growth

based mainly on animal
experiments


Age changes in mandible


Ramus






Moves progressively
posterior by:POSTERIOR PART
Deposition
Resorption

ANTERIOR PART


Ramus
Superior part of ramus
below sigmoid notch

lingual-deposition

Buccal-resorption

Lower part of ramus
below the Coronoid
process

Buccal-deposition

Lingual-resorption

Ramus


Coronoid process


Deposition on lingual side



Resorption on buccal surface


Coronoid process
‘’V’ PRINCIPLE OF ENLOW

Lingual surface


Body of mandible






The increase in width of the mandible
occurs primarily due to resorption on the
inside and deposition on the outside
Increase in length occurs due to drift of
the ramus posteriorly
Increase in height occurs due to eruption
of the teeth

Body of mandible


Ramus corpus junction




Inferior Border of
junction - resorption
Forms Antegonial notch


Antegonial notch
Size depends upon ramus – corpus angle


Lingual Tuberosity




Grows posterior
and medial by
deposition

Resorptive field
belowLingual fossa

Alveolar Process






Adds to the height
and thickness of
the mandibular
body
Teeth absent fails
to develop
Teeth extracted
resorbs

Alveolar Process




Maintain occlusal relationship during
differential mandibular & midfacial
growth– buffer zones

Maintains vertical height


Alveolar Process
Lingual movement of anteriors
Lingual movement of anteriors


Mental Protuberance




Formed by mental ossicles from
accessory cartilage and ventral
end of Meckel’s cartilage
Poorly developed in infants


Mental Protuberance




Forms by osseous
deposition during
childhood
Prominence is
accentuated by
bone resorption
above it


Mental Protuberance






Reversal between 2
growth fields
Concave  convex
Reversal line could
be High or low

Chin


Protrusive chin is unique human trait



More prominent in male



Less prominent in female


Symphysis Menti




Limited growth till
fusion

No widening after
fusion

Mental Foramen


Growth rotation


The ramus
undergoes
remodeling rotation
this produces
displacement
rotation as a whole


Rotation is of two type


Internal rotation
Intramatrix



External rotation

Matrix

Growth rotation










The rotation is considered forward if
growth is more posteriorly than anteriorly.
The rotation is considered backward if
growth is more anteriorly than posteriorly.
Short face -forward growth
Long face -backward growth
Males-slight forward growth
Females-slight backward growth

Factors Affecting Growth
A) Systemic Factors
1. Genetic
2. Hormonal imbalance
3. Nutrition
4. Systemic illness or chronic illness
5. Localized alteration/ diseases of uterus
6. Systemic illness in mother

B) Local factors
1. Vascular abnormality

2. Lymphatic disturbance
3. Neurologic disease
4. Local infection
5. Ear infection or mastoiditis
6. Ankylosis
7. Trauma or fracture
8. Birth injury

Radiographs of midsagital
section’s of mandible
Pre-extraction

High well-rounded

Post-extraction


Knife edge

Low well rounded
With out cortical layer
on crest

Low well rounded
with cortical layer on crest


ANOMALIES OF MANDIBLE


Syndromes associated with mandibular
abnormality
•Pierre-Robin’s syndrome
•Treacher-collins syndrome


Pierre-Robin’s syndrome


Treacher-collins syndrome




Congenital
•Agnathia
•Micrognathia
•Macrognathia




Developmental
•Torus Mandibularis
•Achondroplasia
•Stafne’s cyst
•Odontogenic cyst


Torus mandibularis

Stafne’s cyst

REFERENCES










Oral histology, development, structure and
function – A.R. Ten Cate, 4th Edition
The essentials of facial growth – Enlow and Hans,
1st Edition.
Orthodontics principles and practice – Graber,
3rd edition
Craniofacial Embryology- GH Sperber, 4th
edition
Textbook of oral pathology– William Shafer, 5th
Edition

REFERENCES




Orthodontics art and science-

Bhalajhi,3rd edition
Human embryology- Inderbir singh,7th
edition


Thank you
Leader in continuing dental education


Growth and development of mandible /certified fixed orthodontic courses by Indian dental academy

Recomendados

Recomendados

Mais conteúdo relacionado

Mais procurados

Mais procurados (20)

Destaque

Destaque (20)

Semelhante a Growth and development of mandible /certified fixed orthodontic courses by Indian dental academy

Semelhante a Growth and development of mandible /certified fixed orthodontic courses by Indian dental academy (20)

Mais de Indian dental academy

Mais de Indian dental academy (20)

Último

Último (20)

Growth and development of mandible /certified fixed orthodontic courses by Indian dental academy

Notas do Editor