Development of maxilla/ dental crown & bridge courses

INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

BIBLIOGRAPHY
• Orban’s oral histology & embryology
• Ten cate’s oral histology –Antonio Nanci
• Orthodontics ,The art and science-Dr bhalajhi
• Contemptory orthodontics 2nd edition -Dr Williams Profitt
• Essentials of facial growth-Enlow D H
• A color atlas of oral anatomy, histology & embryology-B.K.B.
Berkovitz
• Color Atlas of clinical oral pathology 2ndedition ;Neville,
Damm, White
• Oral development and histology 2nd edition ; James K Averywww.indiandentalacademy.com

CONTENTS
• Introduction.
• Molecular Genetics of Development.
• Development.
• Osteology.
• Blood Supply to Maxilla.
• Age changes in Maxilla.
• Influence of habit on development.
• Applied Aspect Of Maxilla.

MAXILLA
• Either of a pair of
irregularly shaped
bones of the
skull, fusing in
the midline,
supporting the
upper teeth, and
forming part of
the eye sockets,
hard palate, and
nasal cavity;
upper jaw.

Anterior Aspects of the Skull
Parietal bone
Frontal squama
of frontal bone
Nasal bone
Sphenoid bone
(greater wing)
Temporal bone
Ethmoid bone
Lacrimal bone
Zygomatic bone
Maxilla
Mandible
Infraorbital foramen
Mental
foramen
Mandibular symphysis
Frontal bone
Glabella
Frontonasal suture
Supraorbital foramen
(notch)
Supraorbital margin
Superior orbital
fissure
Inferior orbital
fissure
Middle nasal concha
Perpendicular plate
Inferior nasal concha
Vomer bone
Optic canal
Ethmoid
bone

• Second largest bone of the face
• Paired bone
• Forms the upper jaw, roof of mouth, part of the nasal
cavity floor, and much of the face
• Houses the teeth of the upper jaw
• Contains a large sinus cavity – the maxillary sinus
Maxilla

//
MOLECULAR GENETICS
OF
DEVELOPMENT OF
MAXILLA

HOMEOBOX GENES
• CRANIOFACIAL DEVELOPMENT:
MUSCLE SEGMENT- Msx1 Msx2
DISTALLESS- Dlx
ORTHODONTICAL- Otx
GOOSECOID- Gsc
SONIC HEDGEHOG- Shh

DEVELOPMENT
OF MAXILLA

Growth
• “Growth refers to increase in size” - Todd
• “Growth may be defined as the normal
change in the amount of living substance”-
Moyers
• “Growth usually refers to an increase in
size and number” – Profitt

Growth
•“Growth is entire series of sequential
anatomic and physiologic changes taking
place from the beginning of prenatal
life to senility” - Meridith

Development
• “Development is a progress towards
maturity” – Todd
• “Development refers to all naturally
occurring progressive, unidirectional,
sequential changes in the life of an
individual from it’s existence as a single
cell to it’s elaboration as a multifunctional
unit terminating in death” – Moyers

Development
• “Development connotes a maturational
process involving progressive differentiation
at the cellular and tissue levels” - Enlow

Growth and development of an individual Maxilla
can be divided into PRENATAL & the
POSTNATAL periods. The pre-natal period of
development is a dynamic phase in the
development of a human being. During this
period, the height increases by almost 5000
times as compared to only a threefold increase
during the post-natal period. The pre-natal
life can be arbitrarily divided into three
periods.
1. Period of the Ovum
2. Period of the Embryo
3. Period of the Fetus

"It is not birth, marriage, or
death, but gastrulation, which is
truly the most important time in
your life."
Lewis Wolpert (1986)

• During the pre –Embryonic period, the cells
that will eventually give rise to all
structures of the body differentiate into
three germ layers.
• During this stage (Gastrulation), cell
movements result in a massive
reorganization of the embryo from a simple
spherical ball of cells, the blastula, into a
multi-layered organism.
• Many of the cells at or near the surface
of the embryo move to a new, more
interior location.

• The cells of the embryo form three tissue (germinal) layers
(16 day) :
- Ectoderm (outside layer),
- Mesoderm (middle layer),
- Endoderm (inside layer).
• This is one of the most crucial points in development where
a great deal of differentiation occurs.
Ectoderm
Mesoderm
Endoderm

Prenatal development of maxilla
• The cartilages and bones of the maxillary
skeleton form from neural crest cells that
originated in the mid and hindbrain of the
neural folds. These cells migrate ventrally to
form the mandibular and maxillary facial
prominences where they differentiate into
bones and connective tissue.

The building
blocks for
cephalogenesis

The source and
pattern of neural
crest migration to
the developing face
and branchial arch
system. The
midbrain and
rhombomeres 1 & 2
contribute to the
face and first
branchial arch.

• Initially there are six pharyngeal arches, but 6th one
disappears as soon as it forms leaving only five. They
are separated by branchial grooves.
• The first four branchial arches are well developed in
humans, only first and the second arches extends to
the midline and not interrupted in midline by heart.
• The first arch is called mandibular arch and second is
hyoid arch.

Prenatal Growth Of Maxilla
Around the fourth week of intra-uterine life, a
prominent bulge appears on the ventral aspect of the
embryo corresponding to the developing brain.
Below the bulge a shallow depression which corresponds
to the primitive mouth appears called “
STOMODEUM”.
The floor of the stomodeum is formed by the
buccopharyngeal membrane which separates the
stomodeum from the foregut.

By around the 4th week of intra-uterine life, five
branchial arches form in the region of the future head
& neck. Each of these arches gives rise to muscles,
connective tissue, vasculature, skeletal components,&
neural components of the future face.

The first branchial arch is called the mandibular arch &
plays an important role in the development of the
nasomaxillary region.
The mesoderm covering the developing forebrain
proliferates & forms a downward projection that
overlaps the upper part of stomodeum .This downward
projection is called “FRONTO-NASAL PROCESS”.

The stomodeum is thus overlapped superiorly by the
fronto-nasal process. The mandibular arches of both
the sides form the lateral walls of the stomodeum.
The mandibular arch gives off a bud from its dorsal end
called the “MAXILLARY PROCESS”.

The ectoderm overlying the fronto-nasal process shows
bilateral localized thickenings above the stomodeum.
These are called the “NASAL PLACODES”. These
placodes soon sink and form the nasal pits.
The formation of these nasal pits divides the fronto-
nasal process into two parts:
a) The medial nasal process &
b) The lateral nasal process

The medial nasal processes of both sides,
together with the frontonasal process, give
rise to middle portion of nose, anterior
portion of maxilla & primary palate.
As the maxillary processes become narrow so
that the two nasal pits come closer. The line
of fusion of the maxillary process & the
medial nasal process corresponds to the naso-
lacrimal duct.

The maxillary process grows medially &
approaches the lateral & medial nasal
process but remains separated from them
by distinct grooves. {Naso-optic groove &
bucco-nasal groove.}

• Face develops between the 24 day & 34
day of gestation. By this time, on the
inferior border of maxillary process &
superior border of mandibular arch, the
odontogenic epithelium begins to proliferate
& thicken.
• Thus, the primary epithelial band is an arch
shaped continuous plate of odontogenic
epithelium, that forms in the upper jaw.

Coronal section of embryo showing
membranous bone deposition with formation
of maxilla.In association with cartilage ,
nerve & tooth germ.

OSSIFICATION SITES OF MEMBRANOUS SKULL
BONE

Skeletal units of maxilla

 The maxilla was formerly described as ossifying
from six centers, viz.,
1. One, the orbitonasal, forms that portion of the body of
the bone which lies medial to the infraorbital canal,
including the medial part of the floor of the orbit and
the lateral wall of the nasal cavity;
2. A second, the zygomatic, gives origin to the portion
which lies lateral to the infraorbital canal, including the
zygomatic process;
3. A third, the palatine, is developed the palatine process
posterior to the incisive canal together with the
adjoining part of the nasal wall

4 . A fourth, the pre-maxillary, forms the
incisive bone which carries the incisor teeth
and corresponds to the premaxilla of the
lower vertebrates
5 . A fifth, the nasal, gives rise to the frontal
process and the portion above the canine
tooth; and
6 . A sixth, the infravomerine, lies between the
palatine and pre-maxillary centers and
beneath the vomer; this center, together with
the corresponding center of the opposite bone,
separates the incisive canals from each other.

Post Natal Growth
of Maxilla
• As Maxilla is attached to cranial base it is
influenced by growth of cranium
• Growth of maxilla has four contributing
factors as follows
• Surface remodeling
• Translation or Displacement
• Sutural
• Cartilaginous
Apposition Resorption

Post Natal Growth of
Maxilla
• Growth of Maxilla by displacement
Displacement of maxilla are of two
types
• Primary Displacement
• Secondary Displacement

Post Natal Growth
of Maxilla
• Primary Displacement
• Primary displacement of maxilla occurs by deposition
of bone at maxillary tuberosity
• Although tuberosity grows in posterior direction,
maxilla is displaced in anteriorly
• Secondary Displacement
• As nasomaxillary complex is attached to cranial
base, growth occurring at cranial base displaces
the nasomaxillay complex downwards and forwards.
This is Secondary displacement

Post Natal Growth
of Maxilla
• Growth of Maxilla by displacement
• Primary Displacement •Secondary Displacement

The naso-maxillary complex as it emerges
from beneath the cranium

Maxilla
• Growth of Maxilla by Surface remodeling
• Nasomaxillary complex increase in size by selective
deposition and resorption on its surfaces such that overall
size of nasomaxillary complex increases in all three
dimensions, viz. transverse, vertical, and horizontal

Maxilla
• Growth of Maxilla by Surface remodeling

Growth of the palate exhibiting V
pattern of growth

Maxilla
• Growth of Maxilla at Sutures
• Maxilla is attached to cranium by various sutures
such as
• Frontomaxillary
• Frontonasal
• Zygomatico-temporal
• Zygomatico-maxillary
• Pterygopalatine
• Growth at these sutures, that are oblique and
parallel, causes forward and downward displacement
of nasomaxillary complex

Post Natal Growth
of Maxilla
Growth of
Maxilla
by
Sutures

Post Natal Growth of Maxilla
• Growth of Maxilla by Cartilage
• Nasal septal cartilage plays a role in mid facial
development
• Growth at cartilage pushes maxilla forwards and there
occurs secondary bone formation within various
maxillary sutures

AT BIRTH
Hard palate : length = width
maxillary sinus : not visible
radiographically
1 – 2 years
Extensive remodeling
descent of palate /enlargement of
nasal cavity
Mid palatine suture
growth ceases
Maxilla
No synostosis

Moss Cites three types of bone growth changes
to be observed in the maxilla
1) Those changes that are associated with compensations
for the passive motions of the bone brought about by
the primary expansions of the orofacial capsule.
2) There are changes in bone morphology associated with
alterations in the absolute volume, size shape or
spatial position of any or all the several relatively
independent maxillary functional matrices, such as
orbital mass.
3) There are bone changes associated with the
maintenance of the form of the bone itself.
All these changes do not occur simultaneously but rather
differentially or sequentially.

1) Bone deposition occurs along the posterior margin of
maxillary tuberosity, causes lengthening of the dental
arch & enlargement of antero-posrerior dimension of
entire maxillary body. Thus, helps to accommodate
erupting molars.
2) Bone resorption is seen on nasal cavity & bone
deposition on palatal side, thus a downward shift
occurs, leading to increase in maxillary height.
3) As teeth starts erupting, bone deposition occurs at
alveolar margins. Thus increase in maxillary height &
depth of palate.
4) The entire wall of sinus except the mesial wall
undergoes resorption.This leads to increase in size of
maxillary antrum.

Blood Supply Of
Maxilla

• Maxilla is supply by branches:
i) Maxillary A & N.
ii) Facial A & N.
iii) Infraorbital N.

AGE
CHANGES
IN
MAXILLA

At birth the transverse and antero-
posterior diameters of the bone are
each greater than the vertical.
The frontal process is well-marked and
the body of the bone consists of little
more than the alveolar process, the
teeth sockets reaching almost to the
floor of the orbit.
The maxillary sinus presents the
appearance of a furrow on the lateral
wall of the nose.

In the adult the vertical diameter is
the greatest, owing to the
development of the alveolar process
and the increase in size of the sinus.
In old age the bone reverts in some
measure to the infantile condition; its
height is diminished, and after the
loss of the teeth the alveolar process
is rebsorbed, and the lower part of
the bone contracted and reduced in
thickness.

Influence of functional patterns
and habits on development
1.Sucking habit :
Habits persist beyond the time that the permanent teeth begin to
erupt, may leads to malocclusion like
- Flared maxillary incisors
- Lingually positioned lower incisors
- Anterior open bite

• (The sucking of the cheeks inward around the finger,
squeezes the upper jaw and makes the jaw abnormally
narrow. The presence of the finger between the front teeth
prevents the upper and lower front teeth from growing
towards each other)

2.Mouth breathing :
It could result in different head,
tongue & jaw postures.
To breath through the mouth three
postural changes are required:
1.Lowering the mandible.
2.Positioning the tongue downward
& forward
3.Extending the head.

Therefore this habit may be result in
 long face syndrome, comprising
downward & backward mandibular
growth rotation, excessive posterior
tooth eruption, tendency to maxillary
constriction, excessive overjet &
anterior overbite.

• Applied aspects of development of
maxilla
Most teratogenic agents leading to facial & dental
malformations.
Types of clefts :-
1) Oblique facial cleft (results from lack of fusion
between maxillary process & lateral nasal process).

2)Bilateral cleft lip (lack of fusion between
maxillary process & median nasal process).
3)Microstomia,(excessive merging of maxillary &
mandibular processes).
4)Macrostomia,(faliure of maxillary & mandibular
processes to fuse).

2)Binder syndrome :- (Frontonasal dysplasia)
1) Flattened nose with depressed alar base area
& flattening of maxillary base.

2) Radiograph showing thinnes
of labial plate of alveolar bone
over upper incisors & increase in
nasomaxillary angle.
3)Typical facies,frontal &
lateral views.

3)Maxillofacial dystosis :-
Maxillary hypoplasia, downslanting palpebral
fissures, minor ear anomalies.

4) Orofacial digital syndrome :-
-Pseudocleft in midline of upper lip, widely spaced
eyes.
-Down turned mouth, frontal boosing, hypoplastic
ear cartilages.

-Maxilla is divided into an anterior segment & 2
posterior segment.
-Clefting & division of maxilla.

- Irregular cleft palate.
Malposition of maxillary canine& supernummery
deciduous canine & premolars are common.

Development of maxilla/ dental crown & bridge courses

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