Growth Roataion

Dr. Nilofer Vevai

GROWTH ROTATIONS

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CONTENTS

1. Introduction.

2. Principles of growth and development.

3. Amount and timing of growth.

4. Growth of mandible.

5. Mechanism of rotation.

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7. Growth rotations of mandible.a) Bjork.

i. Direction of growth.ii. Structural signs.a) According to Bjork.

b) According to Petrovic.

iii. Results of implants studies.iv. Type of rotations.

b) Bjork and Skieller.c) Profitt.

d) F.F. Schudy.e) Counterbalancing rotation- Dibbet.

f) Enlow’s Concept.g) Solow & Houston.

h) Solow , Siersbaek – Nielsen.

8. Center of rotation of mandible- Isaacson.

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9. Growth rotations of maxilla.

10.Clinical aspects.

11.Conclusion.

12. References.

INTRODUCTION

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Growth and Development

• Frequently heard together.

Growth is not merely a process of increase in size, but rather is a progressive facial enlargement with differential growth processes in which the various parts develop earlier or later than other parts in different facial region, in a multitude of directions and different rates.

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– Development:

Is a gradual maturational process involving a complex of different but functionally interrelated organs and tissues.

The growth process also involves a succession of regional changes of great proportions and it requires countless localized ‘adjustments’ to achieve proper fitting and function among all the parts.

• According to Moyers RE Handbook of orthodontics 4th Ed:

Development includes all the naturally occuring 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.

Development = Growth + Differentiation + Translocation

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PRINCIPLES OF GROWTH AND DEVELOPMENT

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Principles of growth and development

1. Bone grows by adding new bone on one side of bony cortex and

taking it away from the other side, due to which bone drift

occurs.

2. The inner and outer surface of the bone are covered with

mosaic type appearance of growth fields, which can be

resorbtive or depository. If it is resorbtive on one side it will be

depository on other.

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3. Bone has periosteal and endosteal layer if one is resorbtive then other will be

depository.

4. The control of growth is done by the soft tissue matrix present around the bone.

The blueprint of the design construction and growth of the bone lies in the

composite of muscles, tongue, lips, connective tissue, nerves, blood vessels,

airways etc.

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5. The various sites of growth do not show a

same rate of growth activity.

6. Remodeling is a basic part of growth process.

7. Growth process leads to primary or secondary

displacement.

AMOUNT OF GROWTH

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• Timing of puberty makes a difference in

ultimate body size. The earlier the puberty

the smaller will be the body size.

GROWTH OF MANDIBLE

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• The major parts of Mandible important for/ affecting growth

rotations is:

– The corpus – The ramus

• Corpus of the mandible is a direct structural counterpart to the maxillary corpus

• Ramus is related to the pharyngeal space and middle cranial fossa, with the function being to bridge the middle cranial fossa and place the corpus in proper relation with the cranial floor articulation on one side and maxillary corpus on other side.

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• Ramus undergoes continuing remodeling as a part of its growth process and several basic functions are provided by these changes:

The entire ramus gets progressively

relocated posteriorly by combination

of resorption and deposition.

The ramus width increases to

accommodate the increase in middle

cranial fossa and the pharynx.

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– The length of the ramus increases to accommodate the increased size of

nasomaxillary complex and erupting teeth.– Progressive remodeling changes occur in the

ramus to place the mandibular corpus in proper relation with the maxillary corpus.

• These changes lead to change in orientation of the mandible leading to ROTATION OF THE MANDIBLE.

(Rotation literally means to move round a axis or a centre.)

Types of rotations :

1. Forward rotation

2. Backward rotation

• 1965 - Schudy – counterclockwise = forward clockwise = backward.

• 1970 - Odegard described rotation as change in the orientation that can occur between implant line and

lower border of the mandible.

• 1977-Lavergne and Gasson described the terms Positional and Morphogenetic rotations.

• 1979 - Bjork and Skieller gave the terms -

• Total rotation.

• Matrix rotation.

• Intramatrix rotation

• 1985-Dibbets introduced the term Counterbalancing rotation.

• 1987 - Rune et al disapproved of Bjork & Skieller’s interpretation of rotations.

• 1988- Solow, Houston – introduced new terms

True rotation. Apparent rotation.

Angular change = remodeling of the lower border.

• Profitt - Internal rotation.

Total rotation . External rotation

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• Since classic description of mandibular growth by John Hunter in 1771 there has

been various studies and reports on it.

• He had applied anthropometry (aligned human skulls along symphyseal and

lower border of mandible) to find out how mandible increased in size.

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• He said mandible size increased by 1. Apposition at posterior border,

2. Increase at coronoid and condyloid process above the line of teeth

3. The increase in height was mainly due to increase in alveolar bone.

• Lande - serial cephalometric study

1. Mandible tends to become more prognathic with age

as compared to maxilla

2. Convexity of Face decreased with age.

3. Decrease in the inclination of the Mandible - less

steeply inclined with growth.

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• Later in 1955 Bjork coined the term growth rotations:

“A particular phenomenon occurring during the growth of the head where in lowering of the mandible during

growth was considerably greater dorsally then frontally”

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GROWTH ROTATIONS.

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Bjork study

• Started his study in 1951.

• Had a sample size of 100 children between the age group of 4 – 24 yrs.

• Used metal implants to find the sites of growth and resorption in individual jaws. Also examined individual variation in direction and intensity.

• Analyzed mechanics of changes in intermaxillary relations during growth.

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• He refuted the concept that the given

intermaxillary relation remained static through

out life. Considerable variation in the

development of facial form and intermaxillary

relation was seen.

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Direction of Growth

• Mandible can have a forward direction of growth (good growing) or backward

direction of growth (bad growing).

• Bjork gave seven structural signs to find the direction of mandibular growth.

• These signs are not clearly developed before puberty.

Bjork’s concept• Growth of the mandible occurs essentially at the

condyles.

• The anterior aspect of the chin-stable.

• Lower border of the mandible- At the symphysis-apposition.

At the angle -resorption.

• The appositional and resorptive areas may change-determining the type of growth.

• The growth of the condyle occurs in a upward and forward curving manner.

• The center of rotation may be located-posteriorly or anteriorly or somewhere in between.

• The center may not always lie at the TMJ.

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DOWNWARD & BACKWARD ROTATION

UPWARD & FORWARD ROTATION

FORWARD ROTATION• THREE TYPES:

TYPE I -center at the TMJ.

-underdeveloped anterior face height.

-deep bite.

Cause: occlusal imbalance or powerful musculature.

• Type II

Center at the incisal edges of the lower teeth.

Marked increase in posterior facial height and normal anterior facial

height.

Increase in posterior face height

Lowering of the Increased height of middle ramus cranial fossa.

• Increase in ramus height maybe due to vertical growth

of the condyle.

• But this vertical lowering manifests as forward rotation

–muscular and ligamentous attachments.

• Eruption of the molars keep pace with the rotation.

• Type III

Center of rotation is at the premolars.

Deep bite occurs.

Cause:

Anomalous occlusion-large overjets.

BACKWARD ROTATION• TWO TYPES:

Type I -center at the TMJ.

-underdevelopment of the posterior face height occurs-

open bite.Causes:

1. Middle cranial fossa is raised.2. Orthodontic bite raising

appliance.3. Oxycephaly.

• TYPE II -center at distal most

occluding molars.

Cause: sagittal (backward ) growth of the condyle.

-The mandible is carried forward but due to muscle

and ligaments attachments its rotated backwards.

The eruption of lower molars was hindered-the rotation not due to

overeruption.

Seen in condylar hypoplasia.

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Structural Signs

1. Condylar inclination.2. Mandibular canal inclination.

3. Lower border of mandible (Antegonial notch).

4. Symphysis inclination.5. Interincisal inclination.

6. Intermolar angle.7. Lower face height.

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• CONDYLAR INCLINATION– Forward or backward inclination of the

condylar head is characteristic sign– In forward growing mandible condyle is upright compared to a backward growing mandible in which it is inclined backward

– Is difficult to identify on the lateral cephalogram.

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• MANDIBULAR CANAL– The mandibular canal curvature remains the

same throughout the life.– In vertical growing mandible the curvature of

the canal is more than that of the mandibular contour. Where as in case of horizontal

growers the canal may be flat or may even be curved in opposite direction.

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• Shape of the lower border of mandible.– In vertical growers there is an increased

deposition below the symphysis, anterior part of the mandible becomes thick along with this

there is resorption at the angle producing a characteristic concavity.

– In horizontal growers the anterior rounding is absent so the concavity of the lower border is

absent.

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• INCLINATION OF THE SYMPHYSIS– In horizontal growers chin swings forward to

become prominent.– In vertical growers symphysis is swung

backward causing a receding chin.

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• INTERINCISAL ANGLE– Interincisal angle is almost constant showing that the lower incisors is related functionally to

the upper incisors– In vertical growers angle in less

– In horizontal growers there is an increased interincisal angle.

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• INTERMOLAR ANGLE– In case of forward rotation the molars get more upright increasing the intermolar and

interpremolar angle– while in case of backward rotation the molars become mesially tipped hence decreasing the

intermolar and interpremolar angle

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• LOWER FACE HEIGHT– is increased in case of vertical growth pattern

while is less in case of a horizontal growth pattern

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Continuation …

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Terminology, Rotational Changes of the Jaws

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Condition Bjork Schudy

Anterior growth greater than posterior

Forward rotation Clockwise rotation

Posterior growth greater than anterior

Backward rotation Counter-clockwise rotation

Condition Bjork Schudy

Anterior growth greater than posterior

Backward rotation Clockwise rotation

Posterior growth greater than anterior

Forward rotation Counter-Clockwise rotation

• General Terms ….

Core of the mandible ….

Mandibular Plane….

Mandibular plane to core….

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• Proffit

• Bjork

• Solow

Terminologies:

Bjork Schudy

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PROFFIT

• Rotations occurring in the core of the jaw were called as INTERNAL ROTATION.

Hence is the rotation which is visualized by the implant line.

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• Rotation caused by the surface changes and the alteration in the rate of tooth

eruption is called as EXTERNAL ROTATION.

• According to Profitt Rotation of the core in relation to the mandibular plane.

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• Net rotation occurring due to rotation around the condyle, or rotation of

mandibular plane relative to cranial base, is called as TOTAL ROTATION.

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BJORK AND SKIELLER

• Divided the mandibular rotations into three components

– Total rotation– Matrix rotation

– Intramatrix rotation

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Total Rotation

• Is the rotation of the mandibular corpus

• Is measured as change in inclination of a reference line or a implant line in the

mandibular corpus relative to the anterior cranial base.

• If line anteriorly rotate towards the face then is known as forward rotating and

signated as ‘-’

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Matrix rotation

• Is rotation of soft tissue matrix/ plane of the mandible relative to the cranial base.

• Is shown by a tangential mandibular line.

• It can rotate forward and backward in the same patient with condyles as the centre

of rotation and is described by the term pendulum movement.

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The matrix rotation has its center at thecondyles .

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Intramatrix rotation

• Is the difference between total rotation and the matrix rotation.

• It is an expression of remodeling of the lower border of the mandible.

• It is found out by the change in inclination of an implant line or reference line in the

mandibular corpus to the tangential mandibular line.

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• Rotation of the corpus relative to the tangential line such that it faces front is

called as forward rotation.

• Centre of rotation is somewhere in corpus and depends on rotation of corpus, growth rotation of the maxilla and occlusion of the

teeth.

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• Bjork and Skieller said that three changes occur in Intramatrix rotation

– The mandible “wiggles” in in its matrix– This wiggling is associated with the corpus

and is caused by growing condyle.– The rotation results from or compensates for

genetically predetermined program.

According to Bjork and Skieller

• The mandible “wiggles” within the matrix

• This wiggling is associated with the corpus but is caused by the growing condyle.

• Rotation results from or compensates for, a genetically determined program.

Solow & Houston (1988)

Key to differentiate between :

Angular changes – change in shape - deposition + resorption

- surface accretion and removal

- change in orientation between

reference lines

Rotation -rigid body against another

- sutures

- joints

True rotation of the Mandible:• Rotation of the Mandibular body as represented by

implants or stable trabecular structures , relative to the anterior cranial base.

Apparent rotation of the Mandible• The angular change of the Mandibular line relative to

the anterior cranial base.• Rotation + remodelling

= Matrix rotation (Bjork & Skieller)

Solow , Siersbaek – Nielsen (1986) EJO

ANGULAR REMODELING OF LOWER BORDER

• The Angular change of the Mandibular line when the Mandible is registered on implants or stable

trabecular structures.

• Makes a terminological distinction between - the measure of the amount of remodeling that occurs

at the mandibular border and the rotational process that causes it.

• 50% of true mandibular rotation > 50% efficiency of the counter remodelling process.

Solow & Houston (1988)

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BJORK SOLOW AND HOUSTON

PROFFIT

Rotation of mandibular core

relative to cranial base

Total rotation

True rotationInternal rotation

Mandibular plane relative to cranial

baseMatrix

rotationApparent rotation

Total rotation

Mandibular plane relative to the core

of the mandibleIntra matrix

rotation

Angular remodeling of lower border

External rotation

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• According to Petrovic– In orthognathic type of face the ramus and the

body of the mandible are fully developed, and the width of the ascending ramus is equal to

the height of the body of the mandible, including height of the alveolar process and

the incisors. The condyle and coronoid process are almost in the same plane and

symphysis is well developed.

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– In case of a retrognathic mandible corpus is narrow in molar region. Symphysis is narrow and long, ramus is narrow and short and the

gonial angle is obtuse and the coronoid process is relatively smaller than the condylar

process..

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– In prognathic type the corpus is well developed and wide in molar region.

Symphysis is wider in sagital plane, ramus is wide and long and the gonial angle is acute or

small.

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F.F. SCHUDY

• Rotation of the mandible is a result of dis-harmony between vertical growth, antero-

posterior growth and transverse growth.

• Clockwise rotation is a result of increased vertical growth causing a decrease in bite.

• Counter-clockwise rotation is a result of decreased vertical growth causing a deep

bite.

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• Growth increments causing downward movement of chin is called as vertical growth,

while growth increments causing forward movement of chin are called as horizontal

growth.• If growth at the condyles is more than molar

eruption it causes horizontal growth deepening the bite.

• If growth at the condyles is less then molar eruption is leads to vertical growth and a

decreased bite.

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• There are four vertical growth elements which increase the facial height, these

are:-– Anterior growth of nasion.

– Corpus of maxilla getting palatal plane down.– Eruption of maxillary molars.

– Eruption of mandibular molars.

• Edentulous experiment.

• Condyle growth…… molar growth synopsis.

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Vertical v/s AP growth• Schudy 1964.

• Pogonion formula:

If increments in growth are given in millimeters then the behavior of Pogonion can be predicted in the anteroposterior direction.

Increments observed at

1) Mandibular Condyle.

2) Vertical growth at the corpus of the maxilla (SN plane to ANS –PNS Plane)

3) Vertical growth at the maxillary first molar.

4) Vertical growth at the mandibular first molar.

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P= C- (N-ANS +Mx+Md)

In case of tipping of the palatal plate

Site of First molar tooth observed.

Positional and Morphogenetic Rotation.

• Introduced by Lavergne and Gasson (1977)

Positional Rotation-• Describes the position of mandible within the head.

Morphogenetic Rotation-• Concerns the shape of the mandible.

• Superimposition done on line through condylion and pogonion.

• The angle formed between the 2 implant lines-degree of morphogenetic rotation.

• Similar to Bjork’s intramatrix but not identical.

• Bjork considered key factor of intramatrix to be found in a rotation

of mandibular corpus inside the matrix.

• Lavergne and Gasson –consider the forward and backward growth

of the ramus the main mechanism for shortening and elongating the

effective length.

• “It is a compensating mechanism which is capable of enlarging or reducing mandibular length as measured

along the condylion-pogonion diagonal”

•Sagittal discrepancies-minimized by opening and closing the mandible.

• Bjork and Skieller’s Intramatrix rotation-rotation

of the mandibular core relative to the lower

border is the result of genetically determined

condylar growth.

• Hunterian concept or the Morphogenetic rotation .

• The Hunterian concept or principle of Morphogenetic rotation.

Superimposition based on traditional Hunterian concept of Posterior ramal deposition and Anterior ramal resorption.

Enlarging and reducing the mandibular length measured along the Co-Pog line.

• The puzzle of growth rotation: Dibbets

• Definition

Counterbalancing rotation pertains to circular condylar growth, accompanied by selective coordinated

remodeling, which does not contribute to the incremental growth of the mandible.

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COUNTERBALANCING ROTATION

Change in the inclination of the implant line relative to the mandibular plane.

Superimposed on the implants

• This suggests- 1.when the mandibles are superimposed on the their

contours they are identical in shape and size.

2.The condyle grows on a circular arc (c-c’) with radius from the chin to condyle.

• This concludes- 1.The external configuration need not change.

2.Any depositional-resorptive activity maintains the original contours.

The painting may be rotated within the frame but the external outline, configuration and dimensionality, of the frame is not lost.

• ‘Every deflection of condylar growth direction creates the possibility of compensatory remodeling mostly of the

lower border resulting in intramatrix rotation’.

• Actual effect of growth of the condylar cartilage is neutralized to a given extent.

• Second- The Hunterian concept or principle of Morphogenetic rotation.

Superimposition based on traditional Hunterian conception of Posterior ramal deposition and Anterior ramal resorption.

Enlarging and reducing the mandibular length measured along the Co-Pog line.

• The third option - Based on 2 divergent patterns of mandibular growth.

1.Intramatrix rotation with absence of enlargement.

2.Linear condylar growth-evidencing mandibular enlargement.

Suggested mechanism -

COUNTERBALANCING ROTATION

Intramatrix rotation capable of offsetting growth & also is capable of neutralizing growth to a substantial degree.

Does so by inducing a curvilinear growth direction for Mandibular condyle , - more than is necessary to account

for Mandibular enlargement + selective remodelling.

- Offset condylar growth increments – which can throw the Mandible out of its established equilibrium with the

surrounding skeletal units.- Matrix = trigger / initiator.

COUNTERBALANCING ROTATION IS A MECHANISM THAT -1) Neutralizes growth: The actual path of the condyle relative to fixed and stable points inside the mandible is accompanied by selective remodeling.

2) Resuts in selective enlargement of the mandible, apart and distinct from mechanisms that have been described in literature.

Counterbalancing Proportion• It is the quotient between mandibular and condylar

incremental growth and is expressed as a percentage.

• Condylar growth and mandibular growth are weighted in relation to one another.

• The proportion gives a percentage of condylar relocation that has contributed to actual mandibular enlargement.

• Mandibular growth=

Pg-Ar2 – PgAr1

• Condylar growth=distance from Ar1

to Ar2.

Counterbalancing proportion= Growth from Ar-Pg x 100%

Condylar incremental growth

• According to the concept of congruous mandibular growth the proportion should be 100%.

• But study done by Dibbets shows that it ranges from 50% to 90%.

• This percentage strongly correlates type of malocclusion.• Class III-85%

• Class I -76%• Class II-59%

• According to Profitt Contemporary Orthodontics:

For an average individual with normal vertical facial proportions –

Age 4yrs to adult life: -15o of internal rotation (Core)

25% Matrix rotation

75% Intramatrix rotation.

Total rotation: 2-4o

External rotation: 11-12o

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MAXILLARY GROWTH ROTATIONS

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• Growth of maxilla occurs by two ways– Passive displacement- in primary dentition

period– Active growth by surface remodeling.

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• The maxilla can be divided into

– It’s functional process

• Alveolar process

• Parts of bone surrounding the air passage

– Core.

Contemporary OrthodonticProffit 4th Ed.

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• Implants placed on maxillary alveolar process show that

the core of the maxilla undergoes a small and variable

degree of rotation- forward and backward –

INTERNAL ROTATION,

TOTAL ROTATION (implant line).

MATRIX ROTATION not possible in a maxilla.

Contemporary OrthodonticProffit 4th Ed.

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• Varying degree of resorption on nasal side and deposition on palatal side, varying amount of

eruption of incisors and molars lead to EXTERNAL ROTATION.

• In most individuals the external and internal rotations cancel each other.

• According to Profitt

Mandible Core rotation - -15o

25% Matrix

75% Intramatrix

Total Rotation 2-4o

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CLINICAL ASPECTS

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MUTUAL RELATIONSHIP BETWEEN ROTATING JAW

BASES• Rotation of mandible decides the vertical

proportions of the face.

• Horizontal growers have a – Short lower anterior facial height.

– Predisposed to having a deep bite.

• Opposite of above for the vertical growers.

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• According to Lavergne and

Gasson the mutual rotation

of the upper and lower jaw

can be of following 4 types

1. Convergent rotation. Severe deep bite.

2. Divergent jaw bases. Severe open bite.

In severe cases orthognathic

surgery is required.Dentofacial Orthopedicswith Functional Appliances.Graber T, Rakosi T Petrovic AG2nd Ed .

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3. Cranial rotation of both the

bases.

Horizontal growth pattern.

Maxillary cranial rotation

compensates for the mandibular

rotation.

Normal overbite.

4. Caudal rotation of both bases.

Vertical growth pattern.

Maxillary caudal rotation

compensates for the mandibular

rotation.

Normal overbite.Dentofacial Orthopedicswith Functional Appliances.Graber T, Rakosi T Petrovic AG2nd Ed .

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CLINICAL ASPECTS

1. Growth rotation of mandible influence the amount the teeth can erupt.

2. Also it influences the direction of eruption and ultimate position of teeth.

• Eruption of maxillary teeth is in a downward and forward direction.

– Forward rotation of maxilla causes incisors

to tip forward.

– Backward rotation of maxilla causes incisors

to tip palatally.

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• Eruption of mandibular teeth is in a upward and forward

direction.– Forward rotation of mandible

causes incisors to tip lingually.– Backward rotation of mandible

causes incisors to tip labially.

3. Normal internal rotation rotates mandible forward

uprighting the incisors and allowing the molars to

mesialize.

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4. Normally the forward rotation of the maxilla is less then that of mandible causing the

mandibular arch length to decrease.

• Hence in brachyfacial individuals crowding tends to be more, since the mandibular

incisors tend to retrocline more, decreasing the arch length.

According to Profitt

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Eruption of mandibular teeth upward and forward

Forward rotation of the mandible core carrying the

jaw upward.

Tendency to upright the incisors

Molars tend to migrate mesially, Decrease in arch length/perimeter.

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According to Update on the Wits Appraisal By Alex Jacobson The Angle Orthodontist July 1988.

Counter clockwise rotation:Will reduce the ANB angle.

Clockwise rotation:Will increase the ANB angle.

Treatment Aspects

• According to Pepicelli in his AJODO 2005 The mandibular muscles and their importance in

orthodontics: A contemporary review

The more extreme the rotation of the mandible, during growth in either direction, the greater the clinical problem

for the clinician.

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Extrusive Mechanics

• Most orthodontic mechanics are extrusive, and this extrusion appears to maintain or even increase the

vertical dimension during orthodontic treatment.

• Undesirable molar extrusion more in Dolicofacial pattern.

• During treatment, extrusive forces with such mechanics as intermaxillary elastics or particular headgears should probably be avoided in patients with backward-rotating

tendencies to try to limit, as much as possible,any undesirable backward rotation of the mandible.

The mandibular muscles and their importance in orthodontics: A contemporary review

Pepicilli AJODO 2005

Extractions

• Earlier concept.

• Current concept.

• Reasons:

- Extrusion of posterior teeth and growth.

- Treatment timing:

For Brachyfacial Late mixed dentition stage.

Dolicofacial patients: Adolesence.

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The mandibular muscles and their importance in orthodontics: A contemporary review

Pepicilli AJODO 2005

• According to Proffit the general rule to follow is extrusion done

more easily post surgically whereas intrusion must be

handled presurgically or during surgery.

If facial height is short and distance from the incisal edge to chin is normal – Extrusion of posteriors to move the

chin downwards during surgery.

If lower incisors elongated and face height normal/ excessive - Intrusion

of molars.

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• In short face, deep bite individuals… prior to surgery teeth are aligned Anteroposterior

positioning of the teeth is established excessive spee left.

• Extra thickness of splint on premolar area.• Post surgical leveling.

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Surgical Considerations

• Class II Skeletal pattern with deep bite and HGP.

Post surgical extrusion enhances surgical increase in LFH.

Overcoming of heavy bite force pre-surgically.

• Class II skeletal pattern with deep bite VGP.

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The mandibular muscles and their importance in orthodontics: A contemporary review

Pepicilli AJODO 2005

Muscular Anchorage• The teeth would be controlled with natural anchorage in

a brachyfacial pattern, where the musculature is strong, but there would be less muscular anchorage in

dolichofacial subjects with weak mandibular musculature.

• Hence in case of vertical growers the occlusal forces on the molars are less hence is more easy to loose

anchorage, while in horizontal growers it is difficult to loose anchorage.

• Weaker musculature would be less able to overcome the molar-extruding and bite-opening effects of orthodontic

treatment.

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The mandibular muscles and their importance in orthodontics: A contemporary review

Pepicilli AJODO 2005

Retention

• Brachyfacial patients may tolerate more protrusive and proclined incisors than

dolichofacial patients.

• Lips & Oral musculature.

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The mandibular muscles and their importance in orthodontics: A contemporary review

Pepicilli AJODO 2005

Growth Rotations and Functional Appliance therapy

• According to Dentofacial Orthopedics with Functional appliances by Graber Rakosi Petrovic

Class II correction in Horizontal Growth Pattern and posterior positioning of the mandible : VERY GOOD

Class II correction in anteriorly positioned mandible with vertical growth vector: POOR

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Dentofacial Orthopedicswith Functional Appliances.Graber T, Rakosi T Petrovic AG2nd Ed .

138

Dentofacial Orthopedicswith Functional Appliances.Graber T, Rakosi T Petrovic AG2nd Ed .

139

Functional appliances lead to opening of mandibular plane angle hence are contraindicated in cases of vertical

growers.

Cases with an VGP & open bite prior to treatment were unsuccessful

However according to Patel in his article in the Angle orthodontist, Cephalometric Determinants of Successful

Functional Appliance Therapy 2002.

Of 72 patients those with pretreatment differences being smaller and more retrusive mandible with smaller

anterior and posterior face heights had higher success rates of myofunctional appliance therapy.

• Tongue thrust & differences in clinical manifestations in Horizontal and vertical growth rotations.

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RMEAccording to previous immediately after expansion, there is

downward maxillary displacement and extrusion of the supporting teeth, leading to downward and backward

mandibular rotation.

The opening rotation of the mandible induces cephalometric changes, such as increases in inclination of the

mandibular plane, in lower anterior facial height, and in facial convexity, in addition to evident bite opening

in the anterior region.

However according to this article of study on 25 patients end results not significant.

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Longitudinal Effects of Rapid Maxillary Expansion A Retrospective Cephalometric Study. Garib DG Angle orthodontist 2007

• Molar Distalisation consideration:

Headgear Palatal anchorage Skeletal anchorage

Significant distal positioning of the upper posterior teeth relative to the

maxilla causes elongation/ extrusion of posterior teeth and

increase in the vertical dimension.

Without the above difficult to obtain more than 2-3 mm of molar

distalisation.

142

Dentofacial Orthopedicswith Functional Appliances.Graber T, Rakosi T Petrovic AG2nd Ed .

Conclusion

• Growth rotation though a general topic has far reaching effects clinically be it in patient diagnosis, treatment planning or

treatment delivery.

• Hence the understanding of this subject is essential in our field for a more

wholesome treatment approach and understanding.

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References

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3. Essentials of facial growth – D.H. Enlow.

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5. Prediction of mandibular growth rotation – A. Bjork, AJO, June 1969, pg. 585-599.

6. The puzzle of growth rotation – J.M.H. Dibbets, AJO, June 1985, pg. 473-480.

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7. Mandibular rotations: Concepts and terminology. Solow and W.J.B. Houston, EJO 1988 pg. 177-179.

8. Normal and abnormal growth of the mandible. A synthesis of longitudnal cephalometric implant studies over a period of 25 years. Bjork, Skieller. EJO 1983 pg. 1-46.

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Schudy, AO, 1965, pg-36-50.

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Morphology Bremena; Pancherz. Angle Orthod 2005;75:506–509.

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Dentofac Orthop 1990;98:29-32.

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19. The mandibular muscles and their importance in orthodontics: A contemporary review Pepicilli AJODO 2005.

20. Longitudinal Effects of Rapid Maxillary Expansion A Retrospective Cephalometric Study. Garib DG Angle orthodontist 2007

21. Update on the Wits Appraisal By Alex Jacobson The Angle Orthodontist July 1988.

22. Cephalometric Determinants of Successful Functional Appliance Therapy. Patel et al Angle Orthodontist 2002.

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