GOOD MORNING

PRENATAL AND POSTNATAL GROWTH AND DEVELOPMENT

OF NASOMAXILLARY COMPLEX

PRESENTING BYB.NITIN KUMAR

PG 1ST Yr student

CONTENTS:  1.INTRODUCTION 2.ANATOMY3.DEFINITIONS4.PRENATAL GROWTH PERIOD OF OVUM PERIOD OF EMBRYO PERIOD OF FETUS DEVELOPMENT OF PERIORAL REGION GROWTH OF PALATE5.POSTNATAL GROWTH NASOMAXILLARY COMPLEX MAXILLARY TUBEROSITY MAXILLA PALATE KEY RIDGE MAXILLARY SUTURES ZYGOMATIC BONE NASAL CAVITY ORBIT6.CONCLUSION7.BIBILOGRAPHY 

INTRODUCTION Growth increments and development progress rates

vary considerably during the two major periods of human being i.e. prenatal and postnatal

With the increasing importance of orthopedic concepts and growth guidance, the clinical application of this information is quite apparent

A thorough knowledge of postnatal growth particularly is essential for the dentist, pediatrician, endocrinologist, psychologist, teacher or whoever works with growing child, if he is to make significant clinical application of this information

 

ANATOMY

ORBIT

• SIX BONES COMPRISE EACH ORBIT• Sphenoid, ethmoid, lacrimal, frontal, zygomatic and maxilla• The optic foramen is opening for the optic nerve and ophthalmic

artery• Through the superior orbital fissure the oculomotor nerve, trochlear,

ophthalmic branch of trigeminal nerve, the abducent enter the orbit • The inferior orbital fissure is the entrance to the orbit for infraorbital

nerve• ETHMOID BONE: forms a part of nasal cavity, nasal septum and orbit• It is located anteriorly at the base of cranium and perpendicular to

cribriform plate• LACRIMAL BONE: these are small and fragile. They are located

anterior portion of the medial orbital wall• ZYGOMATIC BONE: forms the cheek

NASAL• NASAL BONE: the nasal bones are oblong bones that form

the bridge of nose• VOMER: form the in posterior and inferior part of nasal

septum• INFERIOR NASAL CHONCHA: lies in the nasal cavity and

articulates with the maxilla

MAXILLA• The maxilla is comprised of two portions joined by a

median suture. It consists of a body and four process.• The frontal process and the zygomatic (malar) process join

the frontal and zygomatic bones.• The alveolar process surrounds and supports the maxillary

teeth, and the palatine process forms the major portion of the hard palate.

• Posterior to maxillary 3rd molar is the bulging of bone known as the maxillary tuberosity.

• The median palatine sutures marks the articulation of right and left palatine process

DEFINITIONS GROWTHTODD - GROWTH IS AN INCREASE IN SIZE, DEVELOPMENT IN

PROGRESS TOWARDS MATURITY

MOYERS – GROWTH MAY BE DEFINED AS NATURAL CHANGES IN THE LIVING SUBSTANCES

KROGMAN – INCRESE IN SIZE, CHANGE IN PROPORTION AND PROGRESSIVE COMPLEXITY

JS HUXLEY- SELF MULTIPLICATION OF LIVING SUBSTANCE

DEVELOPMENT:

TODD: DEVELOPMENT IS PROGRESS TOWARDS MATURITY.

MOYERS: ALL 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 TO DEATH

PRENATAL GROWTHPrenatal life is arbitrarily divided into 3 periods The period of ovum

The period of embryo

The period of fetus

1.THE PERIOD OF OVUM

It is the period from fertilization to the end of the 14th day almost 2 weeks

This period consists primarily of cleavage of the ovum and its attachment to the uterine wall

At the end of this period the ovum is only 1.5mm

2.THE PERIOD OF EMBRYOIt is from 14thday-56th day

As early as 21 days after conception when the human embryo is little more than 3 mm in length the head begins to take shape

The head is primarily made up of prosencephalon

The most inferior portion of the prosencephalon is to become the frontal prominence which overhangs the developing oral groove

Bounding the oral groove laterally are the rudimentary maxillary process

Below the oral groove is broad mandibular arch

The primitive oral cavity (bounded by the frontal process), the 2 maxillary process and the mandibular arch are together called as stomodeum

During 4th week the maxillary process grow forward and unite with frontonasal process to form the maxillary jaw since the median nasal process grow downward more rapidly than the lateral nasal process, the latter do not contribute to the structures which ultimately form the upper limb

3mm EMBRYOA. FRONTAL B.LATERAL VIEW

MIDSAGITTAL SECTION OF 3mm EMBRYO

The depression that forms in the mid line of upper lip is called philtrum. It indicates the line of fusion of the median nasal and maxillary process

Those primordia responsible for facial

development are readily observed by the 5th week of life

Inferior or caudal to the stomodeum

Maxillary process which are growing towards the midline to form lateral parts of upper jaw

The medial nasal process and the maxillary process grow towards each other

In 7th week fusion of maxillary process occur

In 8th week nasal septum has narrowed further the nose is more prominent and external ear may be seen forming.

The nasal pits are broken through in to the upper part of the oral cavity and may now be called nostrils

It is also noted that there is a sharp demarcation between the lateral nasal and the maxillary process ( the nasolacrimal groove)as it close over it is converted in to naso lacrimal duct

3.THE PERIOD OF FETUS

Between 8th and 12th week the fetus triples in length the eye lids and nostrils form and close.

There is relatively greater increase in mandibular

size and anterioposterior maxilla mandibular relationship approaches that of a new born infant.

Tremendous acceleration is seen

12TH WEEK EMBRYOMAXILLOMANDIBULAR RELATION NORMAL, NOSTRILS CLOSED, EYELIDS

FORMED AND CLOSED, FACE APPROACHES HUMAN PROPORTIONS

DEVELOPMENT OF PERIORAL REGION

The face at the 5th week is almost as thick as the sheet of paper

At this time the oral pit is bonded above the frontal area and

below the mandibular arch which appears shovel shape.

At around 6th week two small oval, raised areas appear just above the lateral aspect of future mouth

In next 48 hours the centers of the raised areas become depression as the tissues around them continue to grow anteriorly

The depression deepens in to pits that will become future nostrils

The tissue between the nasal pits is termed

median nasal process and those lateral are called lateral nasal process

The maxillary process fuse with the median nasal

process to form the floor of the nostril.

The lateral nasal process enlarge to form the sides of the nose.

GROWTH OF THE PALATEThe palate begins to develop early in week 6 but

the process is not completed until week 12.

The most critical period during palatal development is the end of 6th week to the begening of 9th week

Entire palate develops from 2 structures primary palate secondary palate

The primary palate is the triangular shaped part of the palate anterior to the incisive foramen

The origin of the primary palate is the deep portion of the intermaxillary segment which arises from the fusion of two median nasal prominences

The secondary palate gives rise to hard and soft palate posterior to incisive foramen

The secondary palate arises from paired lateral palatal shelves of the maxilla

As the nasal septum proliferates downwards and backwards the shelf like palatal ridge take advantage of rapid mandibular growth

With the tongue mass no longer interposed between the palatal process the oral nasal communication is narrowed down

The palatine process continue to grow towards

each other anteriorly and unit with the downward proliferating nasal septum to form the hard palate

This fusion progresses from anterior to posterior

and reaches the soft palate

POSTNATAL GROWTHNASOMAXILLARY COMPLEX There are two basic movements drift and

displacement

Drift is otherwise called cortical remodelling

It is achieved by selective apposition and resorption of cortical surfaces ( both endosteal and periosteal)

Displacement movement of the entire bone it is classified as primary and secondary displacement

Primary displacement( translation) is the movement of bone due to its own growth

Many bones of craniofacial skeleton grow accordingly to enlow expanding v principle

Bone apposition takes place on the inner side of v and resorption on the outer surface

As the v expands the inner and outer portions not only come to occupy new positions but also the bone as a whole has increased in size

During bone growth by primary displacement the entire bone is relocated to a new position but resorbed at the surface in the direction of growth ( anterior surface of maxilla) there is bone apposition at the posterior end to maintain contact with adjacent bone

This is explained using the schematic diagram by Enlow and Bang

Enlow- as bone grow by surface deposition in one direction it is simultaneously displaced in the opposite direction

Maxilla cannot be considered as a separate bone instead its growth is best studied taken into account the whole nasomaxillary complex or midface it is a complex system of sutures through which all the bones are in contact

The sutures are zygomatic maxillaryZygomatic temporalZygomatic frontalFronto maxillaryNasomaxillary etc

The nasomaxillary complex consists of zygomatic bone, maxilla( with palate) , nasal bone, part of frontal ( orbital roof) bone

Motive force behind the growth of maxilla has been attributed to primary displacement, growth at synchondroses, sutures , septal cartilage etc

Primary displacement of maxilla is due to growth of maxillary tuberosity

The tuberosity is considered as a major growth site

Cortical deposition at this site pushes against the posterior structures with a counter anterior thrust that leads to primary displacement

As the cranial base grows anteriorly and superiorly the midface grows anteriorly and inferiorly this is termed secondary displacement

Sutural theory proposes that the sutures of the nasomaxillary complex are the centres of growth

Nasal septal cartilage growth can lead to the anterior growth shift of the complex

The theory of SCOTT that claims nasal septal cartilage to be growth centre has been accepted

MAXILLARY TUBEROSITY AND ARCH LENGTHENING

The horizontal lengthening of the bony maxillary arch is produced by remodeling at the maxillary tuberosity. It is depository field in which the backward facing periosteal surface of the tuberosity receives continued deposits of new bone as long as growth in this part of the face continues

Maxillary tuberosity is a major site of maxillary growth. it does not however, provide for the growth of whole maxilla but relates only to that area associated with the posterior part of the lengthening arch.

The position of maxillary tuberosity is actually established by the posterior boundary of the anterior cranial fossa and any clinically induced deviation could result in a developmental rebound

The whole maxilla undergoes a simultaneous process of primary displacement in an anterior and inferior direction as it grows and lengthens posteriorly

In the growth of the bony maxillary arch tuberosity is moving in 3 directions by bone deposition on the external surface

it lengthens posteriorly by deposition on the posterior facing maxillary tuberosity

it grows laterally by deposits on the buccal surface

it grows downward by deposition of bone along the alveolar ridges and also on the lateral side

MAXILLA• The maxilla develops postnatal entirely by intramembranous ossification. Since there is no cartilage replacement.• Growth occurs in two ways1.By apposition of bone at the sutures that connect the maxilla to the cranium and cranial base2.By surface remodelling

Maxilla grows downwards and forwards in response to various forces. It is surprising fact that as maxilla grows forwards the posterior end is depository to maintain contact with adjacent bones but the entire anterior surface of the maxilla becomes resorptive to maintain the shape and configuration

Bone deposition is seen at the entire inner aspect of the maxillary arch and at the tuberosity

At the anterior concave surface of maxilla the periosteal concavity from ANS to point A is depository and the periosteal surface from point a to alveolar margin is resorptive

The anterior surface of the maxilla till the region of key ridge is resorptive and is concave facing downwards and growing inferiorly

Expanding v principle implies that maxilla grows inferiorly due to deposition on the inner aspect of maxillary arch and palate and resorptive in the outer aspect

The frontal process of maxilla and nasal bone that form the bridge of the nose are depository in the anterior aspect

PALATEDownward drift of palate is extensive

The shallow palate of the new born is not retained in the adult. there is enormous change in both size and shape of the palate with growth

The newborns palate is shallow and the horse shoe shaped dental arch has equal length and width

As age advances the palate receives extensive deposition at the root.

The nasal floor is resorptive, nasal roof is depository

Palatal growth can be explained with the help of expanding v principle deposition on the inner aspect of v ( palatal roof) and resorption on the outer aspect ( nasal floor) expands the v in the direction of open end

The eruption of teeth increases the vertical height of the alveolar bone and depth of palate it increases the width of the bone laterally, according to v principle palate grows in height and width with the leading surface towards growth undergoing deposition

KEY RIDGEVertical crest just below the malar protuberance.

The crest is key ridge

A reversal occurs here

It is important growth site

key ridge is an important site of reversal and remodelling

Although a range of variations occurs in the exact placement of the reversal line, anterior to it most of the external surface of the maxillary arch is resorptive

This is because that part of the bony arch is concave

MAXILLARY SUTURESMost sutures in the facial complex do not simply

grow in the direction perpendicular to the plane of suture itself because of the multidirectional mode of primary displacement and the differential extents of growth among the various bones , a slide or slippage of bones along the plane of interface can be involved

A suture is just another regional site of growth adapted to its own localized, specialized circumstances, just as all the other parts of the bone have their own regional growth processes

It is not possible for a bone to grow just at its sutures as was sometimes implied in years past. Nor is it possible for above to have generalized surface growth without sutural involvement

Another old but invalid idea is that the suture growth system closes down at a given age but the bone continues to enlarge simply by generalized surface deposition

To dispel this notion bone addition on surface x enlarge the surface area of the bone but addition must also be made by deposits at sutural surface y in order to maintain morphologic form

It is apparent that it would not be possible for the bone to enlarge in surface area without corresponding additions at sutural contacts

ZYGOMATIC BONEAs the maxilla is displaced anteriorly, its anterior

surface is resorptive, the zygomatic bone shifts posteriorly

The anterior surface of the zygomatic bone and the medial surface (temporal) are resoptive just like maxilla

The posterior and lateral surfaces are depositoryThis expands the zygomatic bone bilaterally and

bizygomatic width increases with age

NASAL CAVITYThe floor and the lateral walls of nasal cavity are

resorptive with deposition in the medial wall of maxillary sinus

This expands the nasal cavityThe portion of roof near the olfactory fossa is

depository because endocranial surface is resorptive

This remodeling pattern lowers the roof of the nose

The maxillary sinus is resorptive in the lateral wall and depository in the medial wall

ORBITThe orbit is a complex congregation of bones

The orbit has medial and lateral walls, roof and floor. In the medial wall of the orbit, lacrimal and ethmoidal bones are present

As the nasal cavity elongates, medial wall of orbit receives deposition; it also expands laterally

The roof of the orbit is floor of the anterior cranial fossa and this endocranial surface is resorptive to accommodate the growing frontal lobe

Compensatory deposition occurs in the orbital roof to keep this already thin bone intact

Orbit expands by V principle

There is deposition on the inner aspect and resorption on the outer aspect

The supraorbital ridges are depository but the area below and lateral to it, the anterolateral rim of supraorbital rim is resorptive.

The lower border of orbit is almost in line with the nasal floor vertically at birth.

All the bones of the face are secondarily displaced in downward and forward direction.

Though displaced downward, orbit is simultaneously moving away by deposits in the floor.

Thus, different parts of the same bone, orbital surface of maxilla and nasal floor are moving in the opposite directions with growth.

CONCLUSION• Study of prenatal and postnatal growth of

nasomaxillary complex is important in diagnosing the defects associated with it and application of required method to correct the various defects.

BIBILOGRAPHY Orthodontics principles and practice -- GRABER T.M Hand book of orthodontics 4th edition -- ROBERT E MOYERS Essentials of Facial Growth -- DONALD H. ENLOW Textbook of craniofacial growth -- SRIDHAR PREMKUMAR Textbook of orthodontics -- SAMIR E. BISHARA Contemporary orthodontics -- WILLIAM R. PROFFIT Head, neck and dental anatomy -- MARJORIE J. SHORT, DEBORAH LEVIN GOLDSTEIN

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