GROWTH AND DEVELOPMENT OF MAXILLA AND MANDIBLE

Piyush verma MDS 1ST year Dept of PEDODONTICS

CONTENTS

• Introduction

• Growth

• Development

• Pre natal growth of maxilla

• Development of palate

• Pre natal growth of mandible

• Post natal growth of maxilla

• Post natal growth of mandible

INTRODUCTION

The study of head form in man has always been of The study of head form in man has always been of considerable interest to anthropologist, anatomists, & other considerable interest to anthropologist, anatomists, & other students of human growth. In fact, the wide array of students students of human growth. In fact, the wide array of students involved in solving the complex phenomenon of “GROWTH” involved in solving the complex phenomenon of “GROWTH” have been aptly described by Krogman as early as 1943 in have been aptly described by Krogman as early as 1943 in these golden words:-these golden words:-

“ “ Growth was conceived by an anatomist Growth was conceived by an anatomist ,born to a biologist ,delivered by a phyisician,left on a ,born to a biologist ,delivered by a phyisician,left on a chemist’s doorstep & adopted by a physiologist. At an early chemist’s doorstep & adopted by a physiologist. At an early age she eloped with a statistician, divorced him for a age she eloped with a statistician, divorced him for a psychologist & is now being wooed , alternately & psychologist & is now being wooed , alternately & concurrently by an endocrinologist, a pediatrician , a concurrently by an endocrinologist, a pediatrician , a physical anthropologist, an educationalist , a biochemist , a physical anthropologist, an educationalist , a biochemist , a physicist , a mathematician , an orthodontist , a eugenicist & physicist , a mathematician , an orthodontist , a eugenicist & the children’s bureau”.the children’s bureau”.

“GROWTH”

According to “ TODD”According to “ TODD”

““Growth is an increase in size & ,Development is Growth is an increase in size & ,Development is progress towards maturityprogress towards maturity

Some definitions related to GrowthSome definitions related to Growth

As is the nature of growth where in the concepts keep As is the nature of growth where in the concepts keep changing with new research findings there has been no changing with new research findings there has been no single definitions associated with it:single definitions associated with it:Different researchers have defined growth in various ways.Different researchers have defined growth in various ways.

-The self multiplication of living substance – The self multiplication of living substance – JX Huxely.JX Huxely.

-Increase in size, change in proportion & progressive Increase in size, change in proportion & progressive complexity.- complexity.- KrogmanKrogman

-Entire series of sequential anatomic & physiological -Entire series of sequential anatomic & physiological changes taking place from the beginning of prenatal life to changes taking place from the beginning of prenatal life to senility –senility –Meredith.Meredith.

-Quantitative aspect of biologic development per unit of -Quantitative aspect of biologic development per unit of time- time- MoyersMoyers

-Change in any morphological parameter, which is -Change in any morphological parameter, which is measurable- measurable- Moss.Moss.

Terminology Related To Growth:Terminology Related To Growth:

Growth Fields :Growth Fields : The outside & inside surfaces of a bone are The outside & inside surfaces of a bone are blanketed by a mosaic-like, pattern of soft tissues,cartilage or blanketed by a mosaic-like, pattern of soft tissues,cartilage or osteogenic membrane called as osteogenic membrane called as Growth FieldsGrowth Fields.. They were then altered are capable of producing an alteration They were then altered are capable of producing an alteration in the growth of the particular bone. in the growth of the particular bone.

Growth Sites :Growth Sites : Growth sites are growth fields that have a special Growth sites are growth fields that have a special significance in the growth of a particular bone.significance in the growth of a particular bone.Eg. Mandibular condyle in the mandible,Eg. Mandibular condyle in the mandible, Maxillary tuberosity in the maxilla.Maxillary tuberosity in the maxilla. The growth sites may process some intrinsic potential to growth.The growth sites may process some intrinsic potential to growth.

Remodeling :Remodeling : It is the differential growth activity involving It is the differential growth activity involving simultaneous deposition & resorption on all the inner & outer simultaneous deposition & resorption on all the inner & outer surfaces of the bone.surfaces of the bone.Eg. Ramus moves posteriorly by a combination of resorption & Eg. Ramus moves posteriorly by a combination of resorption & deposition.deposition.

Growth centres:Growth centres:

Growth centres are special growth sites which control Growth centres are special growth sites which control the overall growth of the bone, eg: epiphyseal plates of the long the overall growth of the bone, eg: epiphyseal plates of the long bones. These are supposed to have an interinsic growth potential. bones. These are supposed to have an interinsic growth potential.

Mechanism Of Bone GrowthMechanism Of Bone Growth

•Bone is a specialized tissue of mesodermal origin. It forms the Bone is a specialized tissue of mesodermal origin. It forms the structural framework of the body.structural framework of the body.

•Bone is calcified tissue that supports the body & gives points of Bone is calcified tissue that supports the body & gives points of attachment to the musculature.attachment to the musculature.

•Normal bone contains between 32-36% of organic matter.Normal bone contains between 32-36% of organic matter.

•Growth movements are of 3 types:-Growth movements are of 3 types:-

-Bone deposition & resorption-Bone deposition & resorption -Cortical drift-Cortical drift -Displacement-Displacement

TYPES OF OSSIFICATIONTYPES OF OSSIFICATION

Bone formation occurs by 2 methods of differentiation of mesenchymal tissue that may be of mesodermal or ectomesenchymal origin. Accordingly 2types of bone growth ossification are normally seen.

1. Intramembranous ossification: The transformation of The transformation of mesenchymal connective tissue usually in membranous sheets, mesenchymal connective tissue usually in membranous sheets, into osseous tissues.into osseous tissues.

2. Endochondral ossification: The conversion of hyaline cartilage prototype

models into bone.

TheThe interstitial growth expansion capability of cartilage, even under interstitial growth expansion capability of cartilage, even under weight pressure due to its avascularity precluding ischemia, weight pressure due to its avascularity precluding ischemia, Cartilage nutrition is provided by perfusing tissue fluids that are not Cartilage nutrition is provided by perfusing tissue fluids that are not easily obstructed by load pressures) allows for directed prototype easily obstructed by load pressures) allows for directed prototype cartilage growth. The cartilage ‘template ‘ is then replaced by cartilage growth. The cartilage ‘template ‘ is then replaced by endochondral bone accounting for indirect bone growth.endochondral bone accounting for indirect bone growth.

“DEVELOPMENT”

Some definitions related to development

According to TOAD: Development means progress towards maturity

According to MOYERS: 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.

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

1. Period of the Ovum1. Period of the Ovum 2. Period of the Embryo2. Period of the Embryo 3. Period of the Fetus3. Period of the Fetus

Period of the ovumPeriod of the ovum::

This period extends for a period of approximately two This period extends for a period of approximately two weeks from the time of fertilization. During this period the weeks from the time of fertilization. During this period the cleavage of the ovum and the attachment of the ovum to the intra-cleavage of the ovum and the attachment of the ovum to the intra-uterine wall occurs.uterine wall occurs.

Period of the embryoPeriod of the embryo:: This period extends from the fourteenth day to the This period extends from the fourteenth day to the fifty sixth day of intra-uterine life. During this period the major part of fifty sixth day of intra-uterine life. During this period the major part of the development of the facial & the cranial region occurs.the development of the facial & the cranial region occurs.

..

Period of the fetusPeriod of the fetus:: This phase extends between the fifty sixth day This phase extends between the fifty sixth day of intra-uterine life till birth. In this period ,accelerated growth of intra-uterine life till birth. In this period ,accelerated growth of the cranio-facial structures occurs resulting in an increase in of the cranio-facial structures occurs resulting in an increase in their size. In addition, a change in proportion between the their size. In addition, a change in proportion between the various structures also occursvarious structures also occurs

PRENATAL GROWTH OF MAXILLA

•Around the fourth week of intra-Around the fourth week of intra-uterine life, a prominent bulge uterine life, a prominent bulge appears on the ventral aspect of appears on the ventral aspect of the embryo corresponding to the the embryo corresponding to the developing brain.developing brain.

•Below the bulge a shallow Below the bulge a shallow depression which corresponds to depression which corresponds to the primitive mouth appears the primitive mouth appears called “ STOMODAEUM”.called “ STOMODAEUM”.

•The floor of the stomodeum is The floor of the stomodeum is formed by the buccopharyngeal formed by the buccopharyngeal membrane which separates the membrane which separates the stomodeum from the foregut.stomodeum from the foregut.

By around the 4th week of intra-uterine life, five branchial By around the 4th week of intra-uterine life, five branchial arches form in the region of the future head & neck.arches form in the region of the future head & neck.

Each of these arches gives rise to muscles, connective Each of these arches gives rise to muscles, connective tissue, vasculature, skeletal components & neural tissue, vasculature, skeletal components & neural components of the future face.components of the future face.

• These are 4 in number

• 5th arch disappears soon after formation.

• Only the first 2 arches are named; the Mandibular arch & Hyoid arch respectively.

Each of these five arches containEach of these five arches contain – –

1.1. A central cartilage rod that form the skeleton of the arch.A central cartilage rod that form the skeleton of the arch.

2.2. A muscular component termed as bronchomereA muscular component termed as bronchomere

3.3. A vascular component.A vascular component.

4.4. A neural element.A neural element.

The first branchial arch plays an important role in the The first branchial arch plays an important role in the development of the naso- maxillary region.development of the naso- maxillary region.

The mesoderm covering the developing forebrain proliferates & The mesoderm covering the developing forebrain proliferates & forms a downward projection that overlaps the upper part of forms a downward projection that overlaps the upper part of stomodeum .This downward projection is called “FRONTO-stomodeum .This downward projection is called “FRONTO-NASAL PROCESS”.NASAL PROCESS”.

The stomodeum is thus overlapped superiorly by the fronto-nasal The stomodeum is thus overlapped superiorly by the fronto-nasal process. The mandibular arches of both process. The mandibular arches of both The sides form the lateral walls of the stomodeum.The sides form the lateral walls of the stomodeum.

The mandibular arch gives off a bud from its dorsal end called The mandibular arch gives off a bud from its dorsal end called the “MAXILLARY PROCESS”.the “MAXILLARY PROCESS”.

The maxillary process grows ventro-medio-cranial to the The maxillary process grows ventro-medio-cranial to the main part of the mandibular arch which is now called the main part of the mandibular arch which is now called the “MANDIBULAR PROCESS”.“MANDIBULAR PROCESS”.

Thus at this stage the primitive mouth or stomodeum is Thus at this stage the primitive mouth or stomodeum is overlapped from above by the frontal process,below by the overlapped from above by the frontal process,below by the mandibular process & on either side by the maxillary process.mandibular process & on either side by the maxillary process.

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

a)The medial nasal process &a)The medial nasal process & b)The lateral nasal processb)The lateral nasal process

The two mandibular processes grow medially & The two mandibular processes grow medially & fuse to form the lower lip & lower jaw.fuse to form the lower lip & lower jaw.

As the maxillary processes become narrow so As the maxillary processes become narrow so that the two nasal pits come closer. The line of that the two nasal pits come closer. The line of fusion of the maxillary process & the medial fusion of the maxillary process & the medial nasal process corresponds to the naso-lacrimal nasal process corresponds to the naso-lacrimal duct.duct.

DEVELOPMENT OF PALATE

The palate is formed by the contribution of:

• Maxillary process.

• Palatal shelves given off by the maxillary process

• Fronto-nasal process

PRIMARY PALATE

• By the fusion of the maxillary and nasal processes in the roof of the stomodeum the primitive palate (or primary palate) is formed, and the olfactory pits extend backward above it.

• It consists of the maxillary process and medial nasal process.

• The lip and primary palate close during the 4th to 7th weeks of gestation

Primitive palate of a human embryo of thirty-seven to thirty-eight days.

SECONDARY PALATE

The development of the secondary palate commences in the sixth week of human embryological development. It is characterised by the formation of two palatal shelves on the maxillary prominences

• As the palatal shelves grow medially their, their union is prevented by the presence of tongue

• Initially the developing palatal shelves grow vertically toward the floor of mouth

• During 7th week of intrauterine life, a transformation in the position of the palatine shelf occurs

• They change from a vertical to a horizontal position

Various reasons are given to explain how this transformation occurs. They are:

• Alteration in biochemical and physical consistency of the connective tissue of the palatal shelves

• Alteration in vasculature and blood supply to the palatal shelves

• Apperance of an interensic shelf force

• Rapid differential mitotic activity

• Muscular movements

• The 2 palatal shelves, by 8 ½ weeks of intra uterine life are in close approximation to each other

• Initially the 2 palatal shelves are covered by an epithelial lining. As they join the epithelial cells degenerate

• The connective tissue of the palatal shelves intermingle with each other resulting in their fusion

• The entire palate doesnot contact and fuse at the same time. Initially the contact occurs in the central region of the secondary palate posterior to the premaxilla

• From this point, closure occurs both anteriorly and posteriorly

OSSIFICATION OF PALATE

• Ossification of the palate occurs from the 8th week of intra- uterine life. This is an intramembranous type of ossification

• The palate ossifies from a single centre derived from the maxilla

• The most posterior part of the palate does not ossify. This forms the soft palate

• The mid palatal suture ossifies by 12-14 yrs

APPLIED ANATOMY

Cleft lip (cheiloschisis) and cleft palate (palatoschisis), which can also occur together as cleft lip and palate, are variations of a type of clefting congenital deformity caused by abnormal facial development during gestation.

CLEFT PALATE

• Cleft palate is a condition in which the two plates of the skull that form the hard palate (roof of the mouth) are not completely joined

• Palate cleft can occur as complete or incomplete (a 'hole' in the roof of the mouth, usually as a cleft soft palate). When cleft palate occurs, the uvula is usually split. It occurs due to the failure of fusion of the lateral palatine processes, the nasal septum, and/or the median palatine processes (formation of the secondary palate

Incomplete cleft palate Unilateral complete lip and palate Bilateral complete lip and palate

COMPLICATIONS

• Cleft may cause problems with feeding, ear disease, speech and socialization.

• An infant with a cleft palate will have greater success feeding in a more upright position.

• Gravity will help prevent milk from coming through the baby's nose if he/she has cleft palate.

TREATMENT

• Often a cleft palate is temporarily closed, the cleft isn't closed, but it is covered by a palatal obturator.

• Cleft palate can also be corrected by surgery, usually performed between 6 and 12 months.

• If the cleft extends into the maxillary alveolar ridge, the gap is usually corrected by filling the gap with bone tissue. The bone tissue can be acquired from the patients own chin, rib or hip.

STAGE ONE

STAGE TWO• Carried out from 18th month to 5th year of life, generally corresponds to primary dentition phase

STAGE THREE• Spans from 6th to 11th year of life, generally corresponds to mixed dentition phase

STAGE FOUR

• Include the treatment done during the permanent dentition stage, 12-18 yrs of age

PRENATAL GROWTH OF MANDIBLE

The first structure to develop in the primordium of the lower jaw is the mandibular division of trigeminal nerve that preceeded the mesenchymal condensation forming the first arch (mandibular).

The prior presence of nerve has been postulated as being necessary to induce osteogenesis by the production of neutrotrophic factors

MECKEL’S CARTILAGE

Meckel’s cartilage is derived from the first branchial arch around the 41st-45th day of intra uterine life.

It extends from the cartilaginous otic capsule to the midline or symphysis and provides a template for guiding the growth of the mandible.

A major portion of the Meckel’s carlitage disappears during growth and the remaining part develop into the following structures:-

• The mental ossicles

• Incus and malleus

• Spine of sphenoid bone

• Anteriorligament of malleus

• Spheno mandibular ligament

•The mandible is derived from the ossification of an osteogenic memberane formed from ectomesenchymal condensation at around 36- 38 days IU.

•The resulting intramemberanous bone lies lateral to meckel’s cartilage of the first arch.

•A single ossification centre for each half of the mandible arises in the 6th week IU, in the region of the bifurcation of the inferior alveolar nerve and artery into the mental and incisive branches.

• As a result mandibular length increases, the external auditory meatus appears to move posteriorly.

• Bone begins to develop lateral to Meckel’s cartilage during the 7th week and continues until the posterior aspect is covered with bone.

• This is the marked acceleration of the mandibular growth between the 8th and 12th week IU

• Ossification stops at the point, which will later become the mandibular lingula and, the remaining part of meckel’s cartilage continues on its own to form sphenomandibular ligament and the spine process of sphenoid ossification.

• Meckel’s cartilage does, however, persist until as long as the 24th week IU, before it disappears.

ENDOCHONDRAL BONE FORMATIONENDOCHONDRAL BONE FORMATION

Endochondral bone formation is seen in 3 areas of mandible-Endochondral bone formation is seen in 3 areas of mandible-

1)1) The condylar processThe condylar process

2)2) The coronoid processThe coronoid process

3)3) The mental processThe mental process

• At fifth week of intrauterine life , an area of At fifth week of intrauterine life , an area of mesenchymal condensation is seen above the mesenchymal condensation is seen above the ventral part of developing mandible.ventral part of developing mandible.

• At about tenth week it develops in cone shaped At about tenth week it develops in cone shaped cartilage.cartilage.

• It migrate inferior & fuses with mandibular It migrate inferior & fuses with mandibular ramus at about 4 month.ramus at about 4 month.

THE CORONOID PROCESS-THE CORONOID PROCESS-

Secondary accessory cartilage appear in region of Secondary accessory cartilage appear in region of coronoid process at about 10- 14 week of intrauterine life.coronoid process at about 10- 14 week of intrauterine life.

This cartilage become incorporated into expanding This cartilage become incorporated into expanding intramembranous bone of ramus & dissappear before birth.intramembranous bone of ramus & dissappear before birth.

THE MENTAL REGION-THE MENTAL REGION- In mental region , on either side of symphysis , one or two In mental region , on either side of symphysis , one or two

small cartilage appear and ossify in seventh week of small cartilage appear and ossify in seventh week of intrauterine life to become mental ossicles.intrauterine life to become mental ossicles.

These ossicles become incorporated into intramembranous These ossicles become incorporated into intramembranous bone when symphysis ossify completely.bone when symphysis ossify completely.

POST NATAL GROWTH OF MAXILLA

..The growth of naso-maxillary complex is produced by the following mechanisms:

• Displacement • Growth at sutures• Surface remodelling

Displacement:Displacement:

IIt is the movement of the whole bone as a unit.t is the movement of the whole bone as a unit.Displacement can be of two types:-Displacement can be of two types:-

PRIMARY DISPLACEMENT

1. Primary displacement: It occurs by growth of maxillay tuberosity in a posterior direction. This results in whole maxilla being carried anteriorly. The amount of this forward displacement equals the amount of posterior lengthning. This is primary type of displacement as the bone is displaced by its own enlargement.

2. Secondary displacement: A passive or secondary displacement of the naso-maxillary complex occurs in a downward and forward direction as the cranial base grows.

GROWTH AT SUTURES

The maxilla is connected to the cranium and cranial base by a number of sutures. These sutures include:

• Fronto-nasal suture

• Fronto-maxillary suture

• Zygomatico-maxillary suture

• Zygomatico-temporal suture

• Pterygopalatine suture

Sutures are oblique and parallel to each other. This allows the downward and forward repositioning of maxilla as growth occurs at these sutures. As growth of surrounding soft tissue occurs, the maxilla is carried downwards and forward. This leads to opening up of space at the sutural attachments. New bone is formed on either side of the suture. Thus the overall size of the bones on either side increases. Hence a tension related bone formation occurs at sutures

SURFACE REMODELING

Remodeling occurs by bone deposition & resorption to Remodeling occurs by bone deposition & resorption to bring about:bring about:

a) Increase in sizea) Increase in size b) Change in shape b) Change in shape c) Change functional relationshipc) Change functional relationship

Bone deposition & resorption:Bone deposition & resorption:

Bone changes in shape & size by two basic mechanisms, bone Bone changes in shape & size by two basic mechanisms, bone deposition & bone resorption. The bone deposition & resorption deposition & bone resorption. The bone deposition & resorption together is called “ together is called “ BONE REMODELINGBONE REMODELING”.”.

The changes that bone deposition & resorption can produce are:The changes that bone deposition & resorption can produce are:

• Change in sizeChange in size• Change in shapeChange in shape• Change in proportionChange in proportion• Change in relationship of the bone with adjacent structures.Change in relationship of the bone with adjacent structures.

Bone remodeling seen in the midfacial regionBone remodeling seen in the midfacial region

Bone remodeling of the palate resulting in Bone remodeling of the palate resulting in its downward displacement its downward displacement

Growth of the palate exhibiting V pattern of growthGrowth of the palate exhibiting V pattern of growth

EXPANDING “V” PRINCIPLE OF MAXILLA

As the maxilla descends, transversely, additive growth on the free ends increases the distance between them. The buccal segments move outward and downward, as the maxilla itself is moving downward and forward, following the principle of expanding

APPLIED ANATOMY

MAXILLARY HYPOPLASIA

Maxillary hypoplasia is the name that dentists have given to the underdevelopment of the maxillary bones, which produces midfacial retrusion and creates the illusion of protuberance of the lower jaw.

TREATMENT

• Prosthetic replacement

• Maxillary surgery

• Protraction headgear

POST NATAL GROWTH OF MANDIBLE

• Of the facial bones, the mandible undergoes the largest amount of growth post-natally and also exhibits the largest variability in morphology

• The basal bone or the body of mandible forms one unit, to which is attached the alveolar process, the coronoid process, the condylar process, the angular process, the ramus, the lingual tuberosity and the chin.

• The study of post natal growth of the mandible is made easier and more meaningful when each of the developmental and functional parts are considered separately

RAMUS

• The ramus moves progressively posterior by a combination of deposition and resorption

• Resorption occurs on the anterior part of the ramus while bone deposition occurs on the posterior region. This results in drift of ramus in a posterior direction

CORPUS or the BODY OF MANDIBLE

Body of the mandible lengthens as the ramus exhibits bone deposition on the posterior aspect and resorption on the anterior aspect

ANGLE OF THE MANDIBLE

• On the lingual side of the angle of the mandible, resorption takes place on the posterio-inferior aspect while deposition occurs on the antero-superior aspect

• On the buccal side, resorption occurs on the anterio-superior part while deposition takes place on the postero-inferior part. This results in flaring of the angle of the mandible as age advances

THE LINGUAL TUBEROSITY

• The lingual tuberosity moves posteriorly by deposition on its posterior facing surface

• Lingual tuberosity protrudes noticeably in a lingual direction and that it lies well toward the midline of the ramus.

• The prominence of the tuberosity is increased by the presence of a large resorption field just below it

• The resorption field produces a sizeable depression, the lingual fossa

THE ALVEOLAR PROCESS

• As the teeth erupt the alveolar process develops and increases in height by bone deposition at the margins

• The alveolar process adds to the height and thickness of the body of the mandible

• In case of absence of teeth, the alveolar bone fails to develop and it resorbs in the event of tooth extraction

THE CONDYLE

The role of condyle in the growth of mandible has remained a controversy. There are 2 schools of thought regarding the role of the condyle:

• It was earlier believed that growth occurs at the surface of condylar cartilage by means of bone deposition

• It is now believed that the gowth of soft tissues including the muscles and connective tissues carries the mandible forward away from the cranial base( carry away phenomenon)

THE CORONOID PROCESS

The growth of th coronoid process follows the enlarging “V” principle

• Viewing the longitudinal section of the coronoid process from the posterior aspect, deposition occurs on the lingual surfaces of the left and right coronoid process

• Viewing it from the occlusal aspect, the deposition on the lingual of the coronoid process brings about a posterior growth movement in the “V” pattern.

THE CHINTHE CHIN ––

Enlow & harris feel that chin is Enlow & harris feel that chin is “associated with a generalised cortical “associated with a generalised cortical recession in the flattened regions positioned recession in the flattened regions positioned between the canine teeth. The process between the canine teeth. The process involves a mechanism of endosteal cortical involves a mechanism of endosteal cortical growth.”growth.”

As the age advances the growth of chin As the age advances the growth of chin becomes significantbecomes significant

Usually males have prominent chin as Usually males have prominent chin as compared to femalescompared to females

Prominence of mental protuberance is Prominence of mental protuberance is accentuated by bone resorption that occurs accentuated by bone resorption that occurs in the alveolar region above it, creating a in the alveolar region above it, creating a concavityconcavity

APPLIED ANATOMY

MANDIBULAR PROGNATHISM

Pathologic mandibular prognathism is a potentially disfiguring, genetic disorder where the lower jaw outgrows the upper, resulting in an extended chin.

The most common treatment for mandibular prognathism is a combination of orthodontics and orthognathic surgery. The orthodontics can involve braces, removal of teeth, or a bite splint and chin cap.

MANDIBULAR RETROGNATHISMRetrognathia (or retrognathism) is a type of malocclusion which refers to an abnormal posterior positioning of the maxilla or mandible particularly the mandible, relative to the facial skeleton and soft tissues.

TREATMENT – Face mask therapy

CONCLUSIONCONCLUSION

Since the growth of maxilla and mandible has Since the growth of maxilla and mandible has a great influence on the diagnosis, prognosis a great influence on the diagnosis, prognosis and treatment of growth discrepancies in and treatment of growth discrepancies in children, so a thorough knowledge is required children, so a thorough knowledge is required by a pedodontist to treat these discrepancies at by a pedodontist to treat these discrepancies at an early age before the permanent deformation an early age before the permanent deformation occurs.occurs.

REFERENCESREFERENCES1. Gurkeerat singh, textbook of orthodontics

2. S.I Balaji, textbook of orthodontics

3. Inderbir singh, textbook of human embryology

4. Shobha tandon, textbook of Pedodontics

5. Enlow DH, Bang S. Growth and remodelling of the human maxilla, Am J Orthod,1965;51:446-64

6. Ferguson MWJ. Palate development, 1988;32;522-4

7. Enlow DH, Harris DB. Astudy of the postnatal growth of the human mandible,Am J Orthod,1964;50:250-64

8. Sicher H.The growth of the mandible. Am J Orthod, 1947;33:30-35