growth and development of maxilla

GROWTH AND DEVELOPMENT OF

MAXILLA

By- jasmine arneja preceptor-

dr payal sharma

CONTENTS

• Introduction

• Prenatal development of maxilla

• Prenatal development of palate

• Postnatal development of maxilla

• Postnatal development of palate

• Anomalies

• Refernces

• The face has 22 bones in an adult

• MAXILLAE are a pair of pneumatic bones and join together to form the upper jaw

• They house the largest sinus in the body- the maxillary sinus

• Each maxilla assists in forming the boundaries of three cavities:• the roof of the mouth• the floor and lateral wall of the nasal antrum• the wall of the orbit

http://en.wikipedia.org/wiki/Mouth

http://en.wikipedia.org/wiki/Nasal_antrum

http://en.wikipedia.org/wiki/Nasal_antrum

http://en.wikipedia.org/wiki/Orbit_(anatomy)

FRONTAL

PALATINE

ZYGOMATIC

ALVEOLAR

EACH MAXILLA HAS 4 PROCESSES

PRENATAL DEVELOPMENT OF MAXILLA

oThe prenatal life may arbitarily divided into 3 periods.

oThe period of ovum(fertilization to 2 weeks)

oThe period of embryo(2 weeks to 8th week)

oThe period of fetus(8th week to 9th month)

Inderbeer singh; human embryology, seventh edition

PRENATAL EMBRYOLOGY OF MAXILLA

• 4TH WEEK OF INTRAUTERINE LIFE


OSSIFICATION OF MAXILLA

• STARTS AROUND THE 8TH WEEK OF IUL

• INTRAMEMBRANOUS TYPE

The centre of ossification appears in the angle between the division of a nerve i.e. where the anterosuperior dental nerve is giving off from the inferior branch of infra orbital nerve, above that part of the dental lamina from which develop the enamel organ of the canine.

From this centre, the bone spreads :-• Posteriorly: - Below the orbit toward the developing zygoma

• anteriorly: - Towards the future incisor region

• Superiorly: - To form the frontal process

Enlow’s; Essentials of Facial Growth, 4th Edition

DEVELOPMENT OF THE PALATE

• Palate is formed by the • 2 palatal shelves of maxillary process• Frononasal processBut fusion is prevented by the tongueAround the 7th intra uterine week Palatal shelves snap horizontally

The entire palate does not contact and fuse at the same time, initial contact occurs in the region of the secondary palate just posterior to the anterior or primary palatine processes and continues both anteriorly and posteriorly to this point.The growth at mid palatal suture ceases between 1&2 years of age


• WHY?• Alteration of the biochemical and the

physcal consistency of connective tissue in palatal shelves

• Alteration in blood flow• Muscular movements• Withdrawl of the face from against the

heart prominence results in jaw opening and tongue dropping

• Any anomaly in this phase results in non-fusion of the palatal shelves and the premaxilla resulting in a CLEFT PALATE


• PREMAXILLA has two centers of ossification

• The palato-ficial center: Appear at the end of 6 WIU. It starts close to the external surface of the nasal capsule, in front of the anterior superior dental nerve and above the germ of the lateral deciduous incisor. From this center bone formation spreads: • Above the teeth germ of the incisors.• Then downward behind them. To form the inner wall of their alveoli & palatal

part of the premaxilla.

• The prevomerine center ( paraseptal center ): It begins at about 8-9 WIU along the outer alveolar wall. It is situated beneath the anterior part of the vomer bone.

OSSIFICATION OF PREMAXILLA

POSTNATAL DEVELOPMENT OF MAXILLA

POST NATAL DEVELOPMENT OF MAXILLA

• Postnatal growth of maxilla is a multifactorial process

• According to Moss-• Translation (displacement)• Transposition (surface remodeling)


TRANSLATION / DISLOCATION

• Dislocation comprises of movement of the whole bone as it simultaneously expands

• Displacement can be • Primary • Secondary

SCHOOLS OF THOUGHT• Sutural theory• Nasal septal theory• Functional matrix


SUTURAL THEORY

• Sicher believed that craniofacial growth occurs at sutures.

• Maxilla is attached to the cranium by frontomaxillary, zygomaticomaxillary, zygomaticotemporal and pterygopalatine suture, which are more-or-less oblique and parallel to each other

• Thus growth in these areas will push the maxilla downward and forward

• But???• Suture is a tension adapted tissue• Suture doesn’t grow when transplanted• Growth takes place in untreated cases of cleft

palate Enlow’s; Essentials of Facial Growth, 4th Edition

NASAL SEPTUM THEORY

• James Scott

• He viewed cartilaginous sites throughout the skull as primary centres of growth

• cartilage is a pressure-adapted tissue

• Pressure (of the growing brain) accommodating growth of the nasal septum provides a source of physical force that displaces the whole maxilla anteriorly and inferiorly. This sets up field of tension for the sutures, at which bone deposition may now take place.

• But???

• Experiments are not decisive Enlow’s; Essentials of Facial Growth, 4th Edition

FUNCTIONAL MATRIX THEORY

• Melvin moss

• Researches suggest that if there is no primordium for the eye, the orbit does not develop

• Acc to him, the functional soft tissue matrix is the epigenic governing determinant of skeletal growth process and all skeletal growth is secondary, compensatory and mechanically obligatory to it.

• In achondroplastic dwarfs, the midface shows marked concavity and retardation owing to deficient cartilage growth


TRANSPOSITION / REMODELLING

• If you see in the picture, The area previously occupied by the ramus has now been converted into mandibular body of the adult

• This is REMODELLING

• It is a sequence of differential deposition and resorption that results in reshaping and resizing of bone into its adult form

• The surface that faces the direction of movement is depository and that away from it is always resorptive


LACRIMAL SUTURE

• Lacrimal bone is a flake of bony island with its entire perimeter surrounded by sutures, separating it from many bones

• The lacrimal bone acts a key traffic control, providing for slippage of multiple bones along its perimeter

• In itself, the lacrimal bone undergoes remodelling rotation


MAXILLARY TUBEROSITY AND KEY RIDGE

• Maxillary arch grows in 3 directions• Posteriorly deposition on posterior surface of

maxillary tuberosity• Laterally- deposition on buccal surface of

tuberosity• Downward- deposition along alveolar ridge

Endosteal surface is resorptive for growth of maxillary sinus

Reversal occurs at key ridge, where most of the external surface becomes resorptive


ZYGOMATIC ARCH

• Resorption at anterior surface and deposition at the lateral and posterior surfaces

• As a result the zygomatic arches move posteriorly and bilaterally outwards


ORBITAL GROWTHTo compensate for resorption in the endocranial side

To compensate for the downward growth of nasomaxillary complex

To make the supraorbital rim more prominent

V PRINCIPLE= Anterior – lateral- superior relocation of orbit


POSTNATAL DEVELOPMENT OF PALATE


POSTNATAL DEVELOPMENT OF PALATE

• In early pre natal life the palate is relatively long but from the 4th month it widens as a result of mid palatal suture growth and appositional growth along the lateral alveolar margins.


• Growth of the mid palatal suture occurs between 1 and 2 years of age.it is large in its posterior than in its anterior part, so that the posterior part of the nasal cavity widens more than the anterior part.

• Lateral appositional growth continues until 7 years of age by this time the palate achieves its maximum anterior width. Posterior appositional growth continues after the lateral growth has ceased, so that the palate becomes longer and wider during late childhood.


• The appositional growth of the alveolar processes contributes to deepening as well as widening of the vault of the boney palate at the same time adding to the height and breadth of maxillae.

• Ossification does not occur in the posterior part of the palate, giving rise to the region of soft palate. Myogenic mesenchymal tissues of the I, II and IV branchial arch migrates into this facial region supplying the musculature of facial and palate.


DEVELOPMENTAL ANOMALIES AFFECTING MAXILLA

• Cleft palate.• Micrognathia.• Macrognathia.• Treacher collins syndrome (first arch syndrome)

Cleidocranial dyplasia (This is an autosomal dominant Oral features: - This includes high arched palate, with or without clefts, delayed eruption of teeth, malformed roots, and supernumerary tooth)

Craniofacial dysostosis (premature closure of the cranial and facial sutures- severe lack of orbits, nasal, zygomatic and maxillary bone components. Mandible will be normal and they exhibit a class iii malocclusion with a ‘v’ shaped palate)

CLINICAL IMPLICATIONS

• Maxillary excessive growth can be reduced by maturation and increased tonicity of perioral soft tissue. E.g. functional appliance.

• Functional imbalances due to extrinsic factors can be corrected if excess factors are removed. E.g thumbsucking.

CONCLUSION

• It is important for the clinician to know the normal and the abnormal ranges of growth for proper diagnosis, treatment planning and selecting appropriate clinical procedures.

• Orthodontic treatment irrespective of appliance depends to a great extent on adaptive capacity of alveolar process, growth and remodelling.

REFERENCES

• Enlow’s; Essentials of Facial Growth, 4th Edition.

• Graber; Orthodontics, Current Principles and Practice.• Inderbeer singh; human embryology, seventh edition

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