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29 July 20141
Dr. Akash Ardeshana 1st MDS Department of paedodontics &
Preventive 2 The Mandible (Growth And Development) 29 July
2014
Contents 3 Introduction History and background Prenatal
development of mandible Postnatal development of mandible
Development of mandible in relation to various theory of growth
Anatomy of mandible Muscle attachment Age changes Developmental
anomalies 29 July 2014
4 MANDIBL E Largest and strongest bone of the face 1st
pharyngeal arch Articulation with skull shape and Function
INTRODUCTION 29 July 2014
Some historical events JOHN HUNTER (1771) compared a series of
dried mandibles and concluded that in order 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 29 July 20145
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. 29 July 20146
The Evolution of Human Jaw 7 The jaws and teeth of Homo sapiens
have evolved, from the last common ancestor of chimpanzee. Many
factors such as the foods eaten and the processing of foods by fire
and tools have effected this evolution course. ON THE EVOLUTION OF
HUMAN JAWS AND TEETH: A REVIEW, YUSUF EMES , BUKET AYBAR, SERHAT
YALCIN , BULL INT ASSOC PALEODONT. 2011;5(1):37-47 29 July
2014
8 29 July 2014
PRENATAL DEVELOPMENT OF MANDIBLE 9 Start abouth 4th week of
intara- uterine life. Developing brain and the pericardium form two
prominent bulges on the ventral aspect of the embryo. These bulges
are separated by primitive oral cavity or stomodaeum The floor of
the stomodaeum is formed by the bucco-pharyngeal membrane, which
separates it from the 29 July 2014
10 Mesoderm of foregut comes to arranged in the form of six
bars that run dorsoventrally in the side wall of the foregut. These
are called pharyngeal arches. 29 July 2014
11 Coronal section through cranial part of foregut before
formation of pharyngeal arches. 29 July 2014 (Human embryology-
Inderbir Sing Eight edition)
12 Formation of pharyngeal arches 29 July 2014 (Human
embryology- Inderbir Sing Eight edition)
13 First Branchial arch called MANDIBULAR ARCH. Mandibular arch
gives off a bud from its dorsal end called maxillary process. It
grows ventro-medially cranial to main part of the arch which is
called mandibular process. . 29 July 2014
14 Mandibular process of each side grow towards each other.
fuse in midline give rise to mandible. First structure develop in
lower jaw : - Mandibular division of Trigeminal nerve. -
Neurotrophic factor produced by nerve induce osteogenesis. 29 July
2014 (Ten Cates Oral Histology Sixth Edition)
MECKEL'S CARTILAGE 15 It is the cartilage of the first arch In
human beings the Meckel's cartilage has a close positional
relationship to the developing mandible but makes no contribution
to it. At 6 weeks of development this cartilage extends as a solid
hyaline cartilaginous rod, surrounded by a fibrocellular capsule,
from the developing ear region to the midline of the fused
mandibular processes. 29 July 2014
16 The Mandibular branch of trigeminal nerve has close
relationship to Meckels cartilage 29 July 2014
17 On lateral aspect of Meckels cartilage, during the 6th week
of embryonic development, a condensation of mesenchyme occurs in
the angle formed by the division of the inferior alveolar nerve and
its incisor and mental branches. (Ten Cates Oral Histology Sixth
Edition) 29 July 2014
Centre of ossification Intramembraneou s Ossification starts at
the division of mental and incisive branch of inferior alveolar
nerve lateral to meckels cartilage around 7th week IUL. 18 29 July
2014
. 19 From center of ossification bone formation spreads:
Anteriorly - midline Posteriorly - where mandibular nerve divided
into lingual and inferior alveolar branch. Bone formation spreads
rapidly and surrounds the inferior alveolar nerve to form
mandibular canal. Intra-membranous ossification spreads in anterior
and posterior direction forms the Body & Ramus of the mandible.
29 July 2014 Grays Anatomy Fortieth edition
20 Anteriorly bone extends towards midline and comes in
approximation with similar bone forming on opposite side. These two
bones remain separated by fibrous tissue mental symphysis untill
shortly after birth. Continued bone formation increases size of
mandible with development of alveolar process to surround the
developing tooth germ. 29 July 2014
. 21 Ossification spread posteriorly to form ramus of mandible,
turning away from meckels cartilage. This point of divergence is
marked by lingula in adult mandible. 29 July 2014
22 Thus by 10 weeks the rudimentary mandible is formed almost
entirely by membranous ossification with little direct involvement
of Meckels cartilage (Ten Cates Oral Histology Sixth Edition) 29
July 2014
NOW.. What is the fate of the Meckels cartilage? 23 29 July
2014
24 Incus and malleus Spine of sphenoid bone Anterior ligament
of malleus Spheno-mandibular ligament 29 July 2014
SECONDARY CARTILAGES IN MANDIBULAR DEVELOPMENT 25 Further
growth until birth influenced by appearance of secondary cartilage
Condylar cartilage: Coronoid cartilage: Symphyseal cartilage: 29
July 2014
CONDYLAR CARTILAGE 26 appear during 12th week of IUL Rapidly
form cone shape mass which is converted quickly to bone by
endochondral ossification. At the end of 20th week only a thin
layer remains on the condylar head ,persist until the end of the
second decade of life ,providing a further growth 29 July 2014 (Ten
Cates Oral Histology Sixth Edition)
Cartilage fuses with mandibular ramus around 4th month. 27 29
July 2014 (Contemporary orthodontics Williams R. proffit fifth
edition)
CORONOID CARTILAGE 28 Appears at about 4 month of development.
Coronoid cartilage is transient growth cartilage and disappears
long before birth. Cartilage grow as a response of developing
temporalis muscle. Coronoid cartilage become incorporated into
expanding intra-membranous bone of ramus. 29 July 2014 (Ten Cates
Oral Histology Sixth Edition)
SYMPHYSEAL CARTILAGE 29 Two in number Appear in between the two
end of Meckels cartilage. They are obliterated within the first
year after birth. 29 July 2014 (Ten Cates Oral Histology Sixth
Edition)
POST NATAL DEVELOPMENT OF MANDIBLE 30 Right & left
mandibular body fuses at midline symphysis one year after birth.
Mandible appears as single bone. 29 July 2014
29 July 201431 (Contemporary orthodontics Williams R. proffit
fifth edition)
According to MOSS while mandible appears in the adult as a
single bone, it is divisible into several skeleton subunits
Condylar process Coronoid process Angular process Ramus Lingual
tuberosity Body of mandible Alveolar process chin. 29 July 201432
(Facial Growth Donald H. Enlow third ed
The Mandibular Condyle It is a major site of growth
Historically, the condyle has been regarded as a kind of cornucopia
from which the whole mandible itself pours forth. The condyle
functions as regional field of growth that provides an adaptation
for its own localized growth circumstances 29 July 201433
The condylar growth mechanism itself is a clear-cut process.
Cartilage is a special non-vascular tissue and is involved because
variable levels of compression An endochondral growth mechanism is
required for this part of the mandible Endochondral growth occurs
only at the articular contact part of the condyle In Figure the
endochondral bone tissue (b) formed in association with the
condylar cartilage (a) The enclosing bony cortices (c) are produced
by periosteal-endosteal osteogenic activity 29 July 201434
The lingual and buccal sides of neck characteristically have a
resorptive surface. This is because condyle is quite broad and neck
is narrow 29 July 201435
The neck is progressively relocated into areas previously held
by the much wider condyle What used to be condyle in turn becomes
the neck as one is remodeled from the other . This is done by
periosteal resorption combined with endosteal deposition. 29 July
201436
Explained another way, the endosteal surface of the neck
actually faces the growth direction; the periosteal side points
away from the course of growth. This is another example of the V
principle, with the V- shaped cone of the condylar neck growing
toward its wide end. 29 July 201437
The condylar question What is the physical force that produces
the forward and downward primary displacement of mandible ?
proliferation of cartilage towards its contact thereby pushes the
whole mandible away from it. bilaterally condyle lacking mandibles
occupy an essentially normal anatomic position. 29 July 201438
These observations suggested conclusions. First the condyles
may not play the kingpin role of a master center. Second the whole
mandible can become displaced anteriorly and inferiorly into its
functional position without a "push" against the basicranium 29
July 201439
Functional matrix Mandible is carried forward and downward, in
conjunction with the growth expansion of the soft tissue matrix
associated with it It is a passive type of carrying The condyle and
whole ramus secondarily remodels toward it thereby closing the
potential space without an actual gap being created 29 July
201440
Role of condyle It is directly involved as a unique, regional
growth site. It provides an indispensable latitude for adaptive
growth. It provides movable articulation. It is pressure tolerant
and provides a means for bone growth (endochondral) in a situation
in which ordinary periosteal (intramembranous) growth would not be
possible It can also, all too frequently, become involved in TMJ
pathology and distress. 29 July 201441
Clinical Implication 42 Condylar cartilage dose have some
measure of intrinsic, genetic programming, This , however, appears
to be restricted to capacity for continued cellular proliferation .
Cartilage cells are coded and geared to divide and continue to
divide by extra condylar biomechanical forces. So overall
mandibular length be clinically increase or decrease for class II
and class III individuals if this were done during the period of
active condylar growth. 29 July 2014 (Facial Growth Donald H. Enlow
third edition)
Coronoid process 43 The coronoid process has propeller like
twist, so that its lingual side faces three general directions all
at once posteriorly, superiorly and medially. 29 July 2014
When bone is added onto the lingual side of the coronoid
process , growth thereby precedes superiorly and this part of ramus
increased in vertical direction. 29 July 201444
The same deposits of bone on the lingual side also bring about
a posterior direction of growth movement . produces backward
movement of two coronoid process even though deposits on the inside
(lingual) surface. 29 July 201445
These same deposits on the lingual side also bring about medial
direction of growth in order to lengthen corpus area occupied by
anterior part of ramus in mandible 1 becomes relocated and
remodeled into posterior part of corpus in mandible 2. 29 July
201446 (Facial Growth Donald H. Enlow third edition)
Growth at Ramus 47 Resorption occurs on the anterior part of
the ramus while bone deposition occur on posterior region. This
results in a drift of the ramus in a posterior direction. 29 July
2014
Ramus is important as it positions the lower arch in occlusion
It is continuous adaptive to the multitude of changing craniofacial
conditions. increasing mass of masticatory muscle inserted into it.
Bridges the pharyngeal compartment. determines the anteroposterior
positioning of lower arch. accommodates the vertical of face. give
space to accommodate erupting permanent molar. 29 July 201448
(Facial Growth Donald H. Enlow third edition)
Body of the mandible 49 The displacement of former ramal bone
into the posterior part of the body of mandible. In this manner the
body of mandible lengthens. 29 July 2014 (Contemporary orthodontics
Williams R. proffit fifth edition)
Angle of mandible 50 Buccal surface Bone deposition -
postero-inferior surface Bone resorption - antero-superior surface
Lingual surface Bone deposition antero-superior surface Bone
resorption postero-inferior surface 29 July 2014
MANDIBULAR FORAMEN The mandibular foramen likewise drift
backward and upward by deposition on the anterior and resorption on
the posterior part of its rim. The foramen presents a constant
position about midway between the anterior and posterior border of
ramus. 29 July 201451 (Facial Growth Donald H. Enlow third
edition
52 Title Relative position of the mandibular foramen in
different age groups of children: A radiographic study. Author
Poonacha, K. S. Shigli, A. L. Indushekar, K. R. Journal Journal of
the Indian Society of Pedodontics & Preventive Dentistry. Jul-
Aug2010, Vol. 28 Issue 3, p173-178. 6p. 2 Diagrams, 4 Charts. Level
of evidence III Objectives: To assess the relative position of the
mandibular foramen (MF) and to evaluate the measurement of gonial
angle (GoA) and its relationship with distances between different
mandibular borders in growing children between 3 and 13years of
dental age Materials and Methods : The radiographs were traced to
arrive at six linear and two angular measurements from which the
relative position of the MF was assessed and compared in different
age groups to determine the growth pattern of the mandible and
changes in the location of the MF. Result The distances between the
MF and the anterior plane of the ramus were greater than that
between MF and posterior plane of the ramus through all stages.
There was a maximum increase in the vertical dimensions of the
mandible compared with the horizontal dimensions, particularly in
the late mixed dentition period.
ANTEGONIAL NOTCH A single field of surface resorption is
present on the inferior edge of mandible at the ramus corpus
junction. This forms the antegonial notch In vertical growth it is
deep and horizontal growth shallow 29 July 201453 (Facial Growth
Donald H. Enlow third edition)
The lingual tuberosity Grows posteriorly by deposits on the
posterior facing surface. The prominence of tuberosity is increased
by presence of large resorptive fields just below it which produces
a sizable depression, the lingual fossa. 29 July 201454 (Facial
Growth Donald H. Enlow third edition
The alveolar process 55 As teeth erupt the alveolar process
develops and increase in height by bone deposition at the margins.
29 July 2014
The chin 56 In infancy, the chin is usually under developed. As
age advances the growth of chin become significant. The mental
protuberance formed by bone deposition during childhood. Its
prominence is accentuated by resorption that occrus in the alveolar
region above it. 29 July 2014 (Facial Growth Donald H. Enlow third
edition)
Development of mandible in relation to various theory of growth
57 Genetic theory - BRODIE (1941) Cartilaginous theory- JAMES SCOTT
Functional matrix concept- MELVIN MOSS Enlows expanding V principle
29 July 2014
GENETIC THEORY:- This theory states that all growth is
compelled by genetic influence ie: genetic encoding of mandible
determines its growth. 29 July 201458 (Contemporary orthodontics
Williams R. proffit fifth edition)
CARTILAGENOUS THEORY This theory states that the cartilage is
the primary determinant of skeletal growth while bone responds
secondarily & passively. According to this theory, the condyle
by means of endochondral ossification deposits bone, which tends to
grow the mandible. 29 July 201459 (Contemporary orthodontics
Williams R. proffit fifth edition)
29 July 201460 Gilhuus-Moe and Lund k. demonstrated that after
fracture of mandibular condyle in a child ,there was an excellent
chance that condylar process would regenerate to approximately its
original size and a small chance that it would overgrow after the
injury. (Gilhuus-Moe , fractures of the Mandibular condyle in the
Growth period.stockholm: Scandinavian university
book,Universitatsforlaget 1969 Lund k. Mandibular growth and
remodling process after mandibular fracture , odontol Scand
32(64):3-117, 1974)
THE FUNCTIONAL MATRIX CONCEPT 61 If neither bone nor cartilage
was the determinant for growth of the craniofacial skeleton, it
would appear that the control would have to lie in the soft tissue.
View was introduced formally in the 1960s by moss. He theorized
that growth of the face occurs as response to functional needs and
neurotrophic influences and is mediated by the soft tissue in which
the jows are embedded. 29 July 2014
62 Which means the muscles, connective tissues etc. carries the
entire mandible away from the cranial base . The bone follows
secondarily at the condyle to maintain constant contact with the
glenoid fossa. 29 July 2014 (Contemporary orthodontics Williams R.
proffit fifth edition)
63 FUNCTIONAL MATRIX - carries out functions. ex : muscle,
nerve , gland , vessels - There is periosteal capsule and capsular
matrices. SKELETAL UNITS - supports & protects the relative
functional matrices - divided in to macroskeletal &
microskeletal units. 29 July 2014
29 July 201464
ENLOWS EXPANDING V PRINCIPLE This theory states that many
facial bones or a part of the bone follows a v pattern of
enlargement. Deposition is in the inner surface of of v .
Resorption is seen along the outer surface of v. CORONOID PROCESS:
Deposition lingual surface, Resorption-buccal CONDYLE PROCESS:
Deposition-ant. & post. Margins, Resorption-buccal &
lingual surfaces. 29 July 201465 (Facial Growth Donald H. Enlow
third edition)
COUNTERPART PRINCIPLE This principle states that growth of any
given facial or cranial part relates specifically to other
structural & geometric counterpart in the face & cranium
Eg;- The maxillary arch is the counter part of the mandibular arch.
29 July 201466
Anatomy of the mandible 67 It has horseshoe shaped body which
lodges the teeth, and pair of rami which project upwards from the
posterior ends of the body and provide attachment to muscle. 29
July 2014
68 The body: Body has outer and inner surfaces and upper and
lower border. The ramus: Quadrilateral in shape, has two surfaces,
lateral and medial, four borders and the coronoid and condyloid
process. 29 July 2014
LATERAL SURFACE PRESENTS THE FOLLOWING FEATURES 69 1. Symphisis
menti 2. Mental foramen 3. Mental protuberance 4. Mental tubercle
5. The oblique line 6. Condylar process 7. Coronoid process 8.
Mandibular notch 9. Alveolar process29 July 2014
The Medial surface presents the following features 1. Mental
spine 2. Mylohyoid line 3. Submandibular fossa 4. Sublingual fossa
5. Mylohyoid groove 6. Mandibular foramen 70 29 July 2014
71 (Grays Anatomy Fortieth edition) 29 July 2014
72 Attachments and relations of the mandible 29 July 2014
73 Lateral surface (Grays Anatomy Fortieth edition) 29 July
2014
74 Medial surface: (Grays Anatomy Fortieth edition)29 July
2014
TMJ 75 29 July 2014
29 July 201476 Lateral Aspect Medial aspect
AGE CHANGES IN THE MANDIBLE 77 29 July 2014 Human anatomy-BD
Chaurasia Forth Edition
At birth 78 At the birth the mental foramen, opens below the
sockets for the two deciduous molar teeth near the lower border.
The mandibular canal runs near the lower border. The angle is
obtuse. It is 175. 29 July 2014
At Childhood 79 The two halves of the mandible fuse during the
first year of the life. The body becomes elongated in its whole
length, but more especially behind the mental foramen, to provide
space for the three additional teeth developed in this part.
Mandibular foramen slightly above the occlusal plane The angle
becomes less obtuse around 140. 29 July 2014
In adult 80 The mental foramen opens midway between the upper
and lower borders. The mandibular canal runs parallel with the
mylohyoid line. Mandibular foramen 7 mm above the occlusal plane
The angle reduces about 110 or 120 degrees. 29 July 2014
In old age 81 Alveolar border is absorbed, so that height of
the body is markedly reduced. The mental foramen and mandibular
canal are close to the alveolar border. The angle again becomes
obtuse about 140 degrees . 29 July 2014
DEVELOPMENTAL DEFECTS OF THE MANDIBLE 82 29 July 2014
Agnathia 83 Hypoplasia or absent of mandible with abnormally
positioned ears. Autosomal recessive . It is probably due to
failure of neural crest mesenchyme into the maxillary prominence.
29 July 2014 (ShafersTextbook of Oral pathology sixth edit
micrognathia 84 Small jow either the maxilla or the mandible
may be affected. True or aqcuired. Severe retrusion of chin , a
steep mandibular plane angle. 29 July 2014 (ShafersTextbook of Oral
pathology sixth edition )
Macrognathia 85 Abnormally large jow E.g. pagets disease of
bone Acromegaly Fibrous dysplasia 29 July 2014 (ShafersTextbook of
Oral pathology sixth edition )
CORONOID HYPERPLASIA 86 Rare developmental anomaly Result in
limited mandibular movement Unknown etiology. M:F ratio 5:1 May be
unilateral or bilateral Bilateral is more common 29 July 2014 (Oral
and maxillofacial Pathology- Neville third edition)
Condylar hyperplasia 87 Excessive growth of one of the condyles
Cause is unknown, but local circulating problems, endocrine
disturbances, and trauma have been suggested as possible etiologic
factors. 29 July 2014 (Oral and maxillofacial Pathology- Neville
third edition)
Condylar hypoplasia 88 Congenital or acquired congenital:
mandibulofacial dysostosis goldenhar syndrome hemifecial microsomia
29 July 2014
89 Acquired: disturbances of the growth center of the condyle.
29 July 2014 (Oral and maxillofacial Pathology- Neville third
edition)
Bifid condyle 90 Rare Most of have medial and lateral head
divided by an antero posterior grooves. Some condyles may be
divided into an anterior and posterior head Cause is uncertain
Antero-posterior may be traumatic origin. 29 July 2014 (Oral and
maxillofacial Pathology- Neville third edition)
Torus mandibularis 91 Develops along the lingual aspect of the
mandible. Probably multifactorial, including both genetics and
environmental influences. 29 July 2014 (Oral and maxillofacial
Pathology- Neville third edition)
Bibliography 29 July 201492 Ten Cates Oral Histology Sixth
Edition Human embryology- Inderbir Sing Eight edition Contemporary
orthodontics Williams R. proffit fifth edition Facial Growth Donald
H. Enlow third edition Grays Anatomy Fortieth edition Human
anatomy-BD Chaurasia Forth Edition ShafersTextbook of Oral
pathology sixth edition Oral and maxillofacial Pathology- Neville
third edition