Post Natal Development of CB,Mx,Mn

8/2/2019 Post Natal Development of CB,Mx,Mn

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Anoop J PIVth Yr I BDS

SSDC, Varkala


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GROWTH

Growth, according to Todd, its the increase in size

According to Krogmann, its the increase in size,

change in proportion, & progressive complexity

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GROWTH & DEVELOPMENT


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According to Todd, Development is the progress

towards maturity.

According to Moyers ,all naturally occurring

progressive, unidirectional sequential change occurringin the life of an individual as its existence as single cellto its elaboration as a multifactorial unit , terminatingtowards death

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DEVELOPMENT


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Bones of the base of the skull /cranial base are formed

initially in cartilage &are later transformed byendochondral ossificationto bone.

Early in embryonic life , centers of ossification appears inchondrocranium , indicating the eventual location ofbasioccipital, sphenoid , & ethmoid bones that form cranialbase

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ossification proceeds bands of cartillage calledSynchondroses remain b/w the centers of

ossification.

as

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Remains of primary cartilaginous skeleton of cranialbase

Bands of cartillage present b/w sphenoid, ethmoid &

occipital bones

Form important growth sites at the base of the skull


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Types of Synchondroses

Intersphenoidal Fuses at birth

Intraoccipital Fuses at 3-5 yrs Spheno-occipital Fuses at 20 yrs

Spheno-ethmoidal exactly not known

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Cranial base grows by cartilaginous growth in Synchondroseswhich later get calcified


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Fig : Synchondroses


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Fig. showing growth at the synchondrosis. A band of immatureproliferating cartilage cells is located at the center of synchondrosis,while the band of mature cartilage cells proliferate on both sides, awayfrom the center & endochondral ossification takes place on bothmargins. Growth at synchondrosis lengthens this area of synchondrosis

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Spheno occipital Synchondroses are responsible

for most of the lengthening of the cranial baseb/w foramen magnum & Sella turcica postnatalwhich in turn helps in the lengthening /growth

of the Naso maxillary complex

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Morphologically, a synchondrosis is similar to the longbone growth plate, except that growth at thesynchondrosis is not unipolar , but bipolar.

The synchondrosis can be regarded as two growthplates positioned back to back so that they share acommon zone of actively proliferating chondroblasts,or the rest zone.

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HISTOLOGY OF SYNCHONDROSES


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The different zones of the synchondrosis mirror each othersuch that there is cartilage in the centre and bone at each end.

Synchondroses is an area of cellular hyperplasia &hypertrophy in the center with bands of maturing cartilage

cells extending in both directions which eventually beingreplaced by bone.

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Fig. shows histologic appearance ofsynchondrosis with ossification taking placeon both sides of primary cartillage


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Cranial base flexion is a unique cranial feature of

modern human beings and also a reflection of brain

evolution

Fusion along the Spheno-occipital Synchondroses is

believed to be responsible for cranial base flexion,

which develops in concert with the development of the

upper airway and the ability to vocalize.

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CRANIAL BASE ANGLE


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During development, the anterior and posterior cranial baseflexes at the sella turcica in the middle sagittal plane and thusconstitutes an angle in the cranial base, termed the cranialbase angle or saddle angle

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Abnormal growth of cranial base can result in

severe dentofacial deformity eg CraniofacialDysostosis

An obtuse cranial base angle increases thedepth of maxilla & causes Mandibularretrognathism & vice versa

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Clinical implications of

growth of cranial base


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An Obtuse cranial Baseangle causing Maxillary

Prognathism

An Acute Cranial Baseangle causing MandibularPrognathism


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Craniofacial


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Enlows Counterpart Principle

Counterpart principle of craniofacial growth statesthat the growth of any given facial/cranial part

relates specifically to other structural counterpartsin face & cranium.

cranial base growth have effect on maxillary &

mandibular growth .Maxillary growth is based on growth of Anterior

Cranial Fossa

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Similarly width of pharyngeal cavity depends onwidth of middle cranial fossa

Width of Mid-cranial fossa is same as that ramuswidth

ANS- Posterior Nasal Spine length of maxilladetermine the length of Corpus of mandible

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Maxillary tuberosity determining the width of lingualtuberosity

Posterior cranial Fossa determine the mandibularposition

Amount , direction & magnitude of cranial basedetermine the amount , direction & magnitude ofmaxilla & mandible

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POSTNATAL DEVELOPMENT OF MAXILLA

1. Zygomatico-

maxillary2. Zygomatico-

frontal

3. Intermaxillary

4. Frontomaxillary

Connective tissue growth Bone fill at the space

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RemodelingGrowth at sutures Translation

Active growth attuberosity

Periostealmatrix

funtion

Deposition/resorption

Passive

Forward &downward

Capsularmatrix

Nasalseptum


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2 Types -

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Growth Movements

Drift Displacement


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Internal displacement of Nasomaxillary complexitself due to growth .

Its the movement of bone surface caused by

deposition & resorption towards the depositorysurface .Its otherwise called Transformation

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DRIFT


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Displacement is the growth of bone as a whole unitso that the bone is taken away from its articulationwith other bones.

Also called as Translation

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DISPLACEMENT


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Maxilla articulate with the surrounding bone withhelp of sutures.

Sutures incl. Zygomaticomaxillary,Frontomaxillary, Pterygopalatine ,Zygomaticotemporal etc..

According to sicherGrowth in sutures Move

maxilla downwards & forwards

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CONNECTIVE TISSUE PROLIFERATION


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But its only a secondary & not a primary mechanism

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Translation/Displacement is process by whichspecific local areas come to occupy new actualpositions in succession as entire bone enlarges.

2 types

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Active/Primary

Passive/Secon

dary


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Active displacement takes place when the growth atthe tuberosity of the maxilla pushes the maxillaforward.

Passive displacement takes place when maxilla growsdownward & forward by the growth of the Spheno-Occipital Synchondrosisof the cranial base/growth of nasal septum.

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Active/Primary Displacement

Passive/Secondary Displacement


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Passive displacement also takes place when themaxillary bone is translated in space by the growth

of corresponding capsular matrices

Three main capsules w.r.t Nasomaxillary complex

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ORBITAL

NASAL ORAL


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In Remodeling simultaneous resorption anddeposition of the maxilla while maintaining theintegrity & shape of bone.

Maxillary growth matures first in Widthfollowed by Length & Height

Width across the 2nd molar & 3rd molar increasesuntil the end of growth in len`gth

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REMODELLING


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Midpalatal suture is active up to 15 yrs. There isbone fill in the midpalatal area due to suturalgrowth resorption in lateral aspect.

In case of Maxillary sinus sinusenlarges Resorption on inner aspect& deposition on outer aspect

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MAXILLARY WIDTH


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There is removal of bone from periosteum, liningthe inner aspect of the nasal cavity & deposition

takes place in the endosteal surface , allowing theexpansion of nasal cavity

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NASAL CAVITY


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In the antero-posterior direction there is growth

by apposition in the posterior tuberosity area sothat there is increased space for permanent teeth.

As the maxilla moves forward , there is resorption

of the anterior surface of the periosteum fromANS to alveolar margin incisors, resultConcaveanterior margin

Deposition occurs in the ANS to make it makeprominent

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ANTERO-POSTERIOR DEPTH


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Resorption anterior region &

Apposition posterior region

of zygomatic boneresult Translation

of zygomatic bone posteriorly

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In vertical direction maxillary bones increase in height byapposition along the alveolar process

This increase is seen as long as the teeth erupt

This contributes early increase inheight of maxilla

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MAXILLARY HEIGHT


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40% of the maxillary height is achieved by this.

Resorption Palatal surfaces &Deposition Palatal roof

End result Downward shift of palate

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Follows the concept of expanding V by Enlow

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POSTNATAL GROWTH OF

PALATE

Bone deposition inner aspect of V

Direction of growth Wide end of V

Periosteal surface lined by Osteoclasts

Endosteal surface lined with Osteoblasts


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Growth in width is completed first then length &height

Growth in width of Jaws & Dental arches completed

before adolescent growth spurt

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TIMING OF GROWTH IN WIDTH,

LENGTH & HEIGHT


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As the jaws grow in length posteriorly, they alsoincrease in width

for the mandible, both molar & bicondylar widthsshows small increase until end of growth in length

Growth in length & height of jaws continues throughthe puberty .

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In both sexes , growth in vertical height of facecontinues longer than growth in length, with the

late vertical growth in mandible.

Increase in facial height & concomitant eruptionof teeth continue throughout the life, but decline

to adult life

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POSTNATAL GROWTH OF

MANDIBLE Mandible at birth is much smaller in size & there is

slight variation in shape from the adult form

Infant mandible has a short more or less horizontalramus with Obtuse Gonial angle

Mandibular growth continues at relatively steadyrate before puberty.

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The condyles are low & at the position along the

occlusal plane .

Symphyseal suture has not yet ossified

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MANDIBLE IN THE ADULT

Mandible in the adult is different from the mandibleof an infant.

Ramus is longer & gonial angle is less obtuse.

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All those changes taking place with the growth ofmandible is in the form of expanding V.

Its easier to visualize mandible as V-shaped bonethan maxilla because of its horseshoe shape.

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V- PRINCIPLE OF GROWTH


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Fig. showing

Mandibulargrowth in the

form of V

FUNCTIONAL MATRICES OF


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FUNCTIONAL MATRICES OF

MANDIBLE


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Lateral of ramus Deposition &

Lingual surface Resorption

of mylohyoid ridge Coronoid process Apposition

its Lateral surface Resorption

Condyle Resorption atlateral aspect

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GROWTH IN WIDTH


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Thus Inter-ramal distance is efficiently increased bythe growth of mandible following the V- Principle

The growth of mandible in length A-P is by thedeposition of bone at the posteriorsurface of theRamus &

Resorption at theAnteriorsurface

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GROWTH IN LENGTH


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This helps lengthen the mandibleanterior part of the ramus is occupied by posterior

part of the body in the future to Accommodatepermanent molars

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Deposition - +Resorption - -


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Alveolar process height correlates well with theeruption of teeth

Bone deposition taking place in the lowerborder of mandible also contributes to increasein height of the mandible

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GROWTH IN HEIGHT


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Arne Bjork et.al , Dept. Of Orthodontics, Royal

dental college , Copenhagen, Denmark performed

longitudinal Radiographic study by Implant methodfor studying Jaw rotations

Longitudinal study involved about 110 Danish

children of 7 yrs. to 18 yrs old.

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GROWTH ROTATIONS


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Instruments used by Bjork

for inserting metallicimplants in mandible


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3 types of metallicimplants tested

A)Kirschner

wire

B)

Cr-CoAlloy

C)Tantalum

Wire


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For the radiographic profile analysis of mandibular growth, one implant wasinserted in the mid-line of the symphysis, and three on the right side nearest thefilm: under the first and second premolars, and in the external aspect of theramus on a level with the occlusal lines.

TERMINOLOGY OF ROTATIONAL


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condition Bjork ProffitRotation ofmandibular corerelative toCranial Base

Total rotation Internal rotation

Rotation ofMandibular

plane relative toCranial base

Matrix rotation Total rotation

Rotation ofMandibularlane relative to

Intramatrixrotation

Externalrotation

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RM NO OGY O RO A ONA

CHANGES OF JAWS

Relationship b/w Total Internal &


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Total Rotation = Internal Rotation - External Rotation

Relationship b/w Matrix, Total & Intramatrix

Rotation (Bjork)

Matrix Rotation = Total RotationIntramatrix

Rotation

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Relationship b/w Total , Internal &

External rotation (Proffit)


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Bone that surrounds the inferior alveolar nerve

& the rest of the mandible consists of itsfunctional processes

Functional processes incl. muscular processes, the condylar process, functions incase being

the articulation of the jaw with the skull.

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CORE OF THE MANDIBLE


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If implants are placed in areas of stable boneaway from the functional processes, it can beobserved that In most individuals , the core ofthe mandible rotates during growth in a waythat tend to decrease the mandibular planeangle

(i.e up anteriorly & down posteriorly)

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Bjork & Skieller distinguished 2 contributions to Internal rotation(Total rotation) of the mandible

Matrix Rotation/rotn around Condyle

Intramatrix Rotation/rotn centeredwithin the body of the mandible

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Totalrotation


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Variation of internal rotation of mandible b/windividuals, ranging up to 10 to 15 degrees.

For an average individual with normal verticalfacial height there is about -15 degrees internalrotation from age 4adult life

25% - Matrix rotation &

75% - Intramatrix rotation69


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When the core of the mandible rotates forward an averageof 15degrees, orientation of jaw from outside

decreases only 24 degrees(av..)

Internal rotation is not expressed in jaw orientation , surfacechanges tends to compensate i.e. ,posterior part of lowerborder of mandible may be the area of resorption, whileanterior aspect of lower border is unchanged / littleapposition

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Reason


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SHORT FACED INDIVIDUALS/FORWARD ROTATORS

These individuals are characterized byshort anteriorlower facial height

Excessive forward rotation of mandible, due to anincrease in normal internal rotation & a decrease in

external compensation

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Square type jaw + Low mandibular planeangle+ Square Gonial angle +skeletal Deep bitemalocclusion + crowded Incisors

Muscles much stronger they mature early

Space closure is very difficult .

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Facial height ratio (upper : lower )50 : 50 / 50 :

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Mandible shows an opposite ,backward rotationwith an increase in mandibular plane angle

Weak musculature & mature late , so avoid mechanicswhich increase vertical height of patient

facial height ratio (upper: lower) is exaggerated

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Avoid bite planes

Avoid anchor bends

Avoid class II elastics

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In these patients we should avoid :-


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This type of rotation is normally associatedwith Skeletal Anterior Open Bitemalocclusion(because chin rotates back well asdown)

Backward rotation of mandible also occurs inpatients with abnormalities/pathological changes

affecting the TMJ

In TMJ patients growth of condyle is restricted

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INTERACTION BETWEEN JAW ROTATION


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Rotation pattern of jaw growth obviously influencestooth eruption

It can also influence the direction of eruption &ultimate antero-posterior position of incisor teeth .

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INTERACTION BETWEEN JAW ROTATION

& TOOTH ERUPTION


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Path of eruption of Maxillary teeth is downward& forward

Normally maxilla rotates slightly few degreesforward & frequently backward

Forward Rotation tends to tipincisors forwards & increasing their prominence.

Backward Rotation directs ant.teeth more posteriorly than normal, up righting them& decreasing their prominence

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Movement of teeth relative to cranial base obviouslycould be produced by

Translocation bring about of the total maxillarytooth movement during adolescent growth

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Eruption path of mandibular teeth is upward &

forward.

Normal Internal rotation of the mandible carries

the jaw upward in front

This rotation alters the eruption path of incisors,tending to direct them more posteriorly thanwould other wise have been the case.

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When excessive rotation occurs in short face type ofdevelopment, the incisors tend to carried into an

overlapping position even if they erupt very little;hence the tendency for Deep Bite Malocclusion

The rotation also progressively uprights incisors,

displacing them lingually & causing a tendency

towards Crowding

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In long face growth pattern anterior open bite willdevelop as the anterior face height increases unlessincisor erupt for an extreme distance

Rotation of jaw also carries the incisor forward ,creating a dental protrusion

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AGE CHANGES IN GROWTH


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Change insoft tissueslike Nose&

Lips

Change in

Eruption Active &Passive

Alignment

changes &changes inOcclusion

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AGE CHANGES IN GROWTH

PATTERN

CHANGES IN FACIAL SOFT


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Changes in soft tissue not only continues withaging, they are much larger in magnitude thanchanges in hard tissue .

The Lips &other soft tissues of face , sag downwardwith aging.

The result is a decrease in exposure of upperincisors, & an increase in exposure of lowerincisors , both at rest & on smile

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CHANGES IN FACIAL SOFT

TISSUE


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With aging , Lips also become progressively thinner,

less vermillion display.

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Active Eruption

Active eruption has been described as the eruptionprocess of a tooth and their alveoli through thegingival tissues (Moshrefi 2000). This phase endswhen the tooth makes contact with the opposing

dentition but may continue with occlusal wear or lossof opposing teeth (Dolt 1997).

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CHANGES IN ERUPTION

PASSIVE ERUPTION


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Passive eruption begins once active eruption hascompleted. This takes place as the dentogingival unitmigrates in the apical direction until it is adjacent tothe cemento-enamel junction (CEJ) (Evian et al. 1993).

In contrast to active eruption, passive eruption is the

apparent lengthening of the crown due to the loss ofattachment, or recession of the gingiva, also due toinflammation.

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PASSIVE ERUPTION


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Passively

eruptedteeth

Aftersurgical

Correction

CHANGES IN ALIGNMENT &


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Its due to

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CHANGES IN ALIGNMENT &OCCLUSION

Lack ofAttrition

Pressurefrom 3rdMolars

Latemandibular Growth


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Raymond Begg ,a pioneer Australian orthodontist noted hisstudies of Australian aborigines that malocclusion isuncommon but large amounts of interproximal & occlusalattrition occurred

He concluded that in modern populations the teeth becamecrowded when attrition didnt occur with soft diets, &

advocated wide spread extraction of premolar teeth to

provide equivalent of the attrition he saw in aborgines

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LACK OF ATTRITION

PRESSURE FROM THIRD MOLARS


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a) Late incisor crowding coincides with the time oferuption of 3rd molars

b) So one school of thought says that the pressure

from the erupting 3rd

molars, causes mesialmigration of teeth,which is the reason for lateincisor crowding

c) But the amount of pressure from 3rd molars is notsufficient to cause pressure effect & changes inlower incisors

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PRESSURE FROM THIRD MOLARS

A A A G O


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Mandibular growth continues even after thecessation of the maxillary growth in late teens

When mandible grows forward relative to maxilla,

in late teens mandibular incisors tends to movelingually, particularly if any excess rotation ispresent.

Due to the mandibular growth, if there where anytight anterior occlusion before the late mandibular

growth occurs one of the 3 of the following canoccur 96

LATE MANDIBULAR GROWTH

Mandible is displaced distally & can cause TMJ


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Mandible is displaced distally & can cause TMJdistortion & displacement of Articular disc

Upper incisors may flare forward, openingspace b/w the teeth

Lower Incisors may displace distally & become

crowded

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CONCLUSION


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Malocclusions & Dentofacial deformity arises through variationsin normal developmental process

A thorough background in craniofacial growth & development is

necessary for every dentist

A thorough knowledge is also necessary because orthodontictreatment involves the manipulation of skeletal growth & dental

growth .

So once alteration/modification is been done, its done for ever

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CONCLUSION

BIBILIOGRAPHY


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Contemporary Orthodontics - William R Proffit

Relationship b/w - Open Anatomy Journal

synchondrosis & craniofacial gth 2010/ Vol 2

Journal of Dental Research - http//jdr.Sagepub.com

Sutural Growth by Implant - http//ejo.oxfordjournals.orgmethod

Morphogenic analysis of facial

growth - Enlow

Orthodontics (Art & Science) - S I Balaji

Orthodontics - Sridhar Premkumar

Textbook of orthodontics - Gurkeerat Singh99

BIBILIOGRAPHY


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Post Natal Development of CB,Mx,Mn