Growth rotations /certified fixed orthodontic courses by Indian dental academy

GROWTH ROTATIONS

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INDIAN DENTAL ACADEMY

Leader in continuing dental educationwww.indiandentalacademy.com


Contents

• Introduction• Terminologies• Concepts of Mandibular growth Rotations• Concepts of Maxillary growth Rotations• Prediction of Mand growth Rotation• Interaction b/n jaw Rotation &Tooth eruption• Clinical implications• conclusion


Introduction

Since Cephalometrics introduced in 1930, originally used to reveal The Anatomy of head

Longitudinal study is possible, soon employed to test various Concepts of mechanisms of postnatal growth of head


Introduction

Longitudinal Cephalometrics analysis of profile radiographs shows that facial shape is remarkably constant during growth


• Until the use of metallic implants the extent to which the mand & maxilla rotate during growth was not appreciated

• The Rotation tends to be masked by surface remodeling


• Lande in 1952 observed that the lower border of the mand becomes less steeply inclined

• The phrase “GROWTH ROTATION” was introduced in 1955 by Bjork

• With the use of metallic implants, He could infer the sites & amt of growth & resorption

• Superimposing 2 consecutive tracings showed that the older Mand rotated



Forward Rotation (Bjork)

Counterclockwise Rotation (shudy) Posterior growth is greater than Anterior

Backward ward Rotation (Bjork)

Clockwise Rotation (shudy)

Anterior growth is greater than posterior



TERMINOLOGIES

• 1965-Schudy introduced clockwise and counterclockwise rotation.

• 1969-Bjork discussed different directions of rotation of the mandibular implant line and the relation of these to mandibular form.


• 1970-Odegard described rotation as the 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.

• 1983-Bjork and Skieller gave the terms- Total rotation. Matrix rotation. Intramatrix rotation


• 1985-Dibbets introduced the term Counterbalancing rotation.

• 1988-Solow,Houston

True rotation.

Apparent rotation.

Angular remodeling of the lower border.

• Proffit- used the terms

Internal rotation.

Total rotation .

External rotation.www.indiandentalacademy.com



• Is the rotation of the mandibular corpus

and is measured as a change in

inclination of the implant line, in the

mandibular corpus relative to the

anterior cranial base.

TOTAL ROTATION / TRUE ROTATION / INTERNAL ROTATION


If the implant line rotates forwards, the total rotation is designated as Negative

The Total Forward Rotation is indicated by converging sella – nasion lines



MATRIX ROTATION / APPARENT ROTATION / TOTAL ROTATION

• Rotation of the soft tissue matrix of the mandible relative to the Anterior cranial base

• The soft tissue matrix is defined by the Tangential mandibular line(ML1)

• Is designated as Negative,when Tangential mandibular line rotates forwards


The matrix rotates forwards & backwards in same individual during the growth period – PENDULUM

MOVEMENT

Center of Rotation – Condyles



INTRAMATRIX ROTATION/ ANGULAR REMODELING/

EXTERNAL ROTATION

Defined as the change in inclination of an implant line in the mandibular corpus relative to the tangential mandibular line

Intramatrix Rotation is an expression of remodeling at the lower border of the mandible



• Forward Rotation of the corpus relative to the tangential mand line is recorded as Negative

• Center of rotation is somewhere in the corpus

• Depends on rotation of corpus of mand & rotation of maxilla & occlusion of teeth


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• The diff b/n Total Rotation & Matrix Rotation is intramatrix Rotation


• According to Bjork & Skieller’ “Intramatrix” concept

First,the mandible “wiggles” with in the matrix Second,this “wiggling” is associated

predominantly with the corpus, but is caused by the growing condyle

Third, Rotation results from or compensates for, a genetically determined program


Total Rotation

True Rotation

Internal Rotation

Matrix Rotation

Apparent Rotation

Total Rotation

Intramatrix Rotation

Angular Remodeling of lower border

External Rotation

Rotation of Mandibular core relative to cranial base implants

Rotation of Mandibular plane relative to cranial base

Rotation of Mandibular plane relative to core of Mandible

BJORK SOLOW, HOUSTON

PROFFIT


• The Total Rotation = Matrix Rotation

+

IntraMatrix Rotation


• The center of Total Rotation depends on other two centers of Rotation

• The pattern of vertical facial development is strongly related to the Rotation of both the jaws

• For an average individual with normal vertical

facial height

• Total Rotation = – 15

Matrix Rotation = –4

IntraMatrix Rotation = –11 www.indiandentalacademy.com

“Positional” & “Morphogenetic” Rotation

Given by Lavergne & Gasson

Positional Rotation deals with the position of the mandible with in the head


Morphogenetic Rotation

• concerns the shape of the mandible itself

• super imposing the two tracings on a line through condylion & pogonion

•The angle b/n two implant lines is determined & this corresponds to the degree of morphogenetic Rotation

• similer to Bjork’s Intramatrix Rotation but not identical


Lavergne & Gasson-Found the effective

mechanism in Ramus, its forward or backward growth,therby shortening or elongating the effective length of the mandible

Bjork & Skieller consider the key factor of Intramatrix rotation to be found in a rotation of the mandibular corpus inside its matrix


• Maxillary – Mandibular sagittal discrepancy is minimized by opening or closing the gonial angle


“It is a compensating mechanism which is capable of enlarging or reducing mandibular length as measured along the condylion-pogonion diagonal”


J.M.H.Dibbets

• Re-examination of the concept of “Intramatrix Rotation" as defined by Bjork & Skieller & also explored by Lavergne & Gasson

• Three diff interpretations of Intramatrix concept are


• First option - Bjork & Skieller define the “Intramatrix Rotation” as

The Rotation of the mandibular corpus relative to the lower border is a result of genetically determined condylar growth both in magnitude & in direction


Bjork approach Superimposing two tracings of the same mandible registered upon natural reference structures shows Rotation


Divergence of implant lines indicatesIntramatrix rotation

Superimposed on implant markersIndicates extensive remodeling


• The condyle grows on a circular arc with radius from center at chin to the condyle.

• When two tracings are superimposed on their contours, they are identical in size & shape.

• The external configuration of mandible need not change in order to allow ‘Intramatrix rotation’

• Any Depositional or Resorptive activity maintains original contours


Painting rotated with in frame but external configuration & dimensions do not change


• The bony element can rotate with in its periosteal frame

• Every deflection of condylar growth creates the possibility of compensatory remodeling, mostly resorption of the lower border resulting in Intramatrix rotation

• Intramatrix Rotation neutralizes the condylar growth.


Second option-Hunterian conceptor Morphogenetic rotation

Posterior ramal deposition &Posterior ramal deposition &Ant resorptionAnt resorption

The direction of condylar growthThe direction of condylar growthfollows pattern that enlarges the follows pattern that enlarges the Mandible maximallyMandible maximally


Third option - Dibbets• Two divergent patterns of mandibular growth

• 1)Circular growth pattern of condyle, resulting in Intramatrix Rotation without any enlargement of mandible

• 2)linear growth pattern of the condyle, characterized by the absence of intramatrix rotation but evidencing mandibular enlargement.

suggested mechanism

Counterbalancing Rotationwww.indiandentalacademy.com

Counterbalancing Rotation

“Counterbalancing Rotation pertains to circular condylar growth, accompanied by selective coordinated remodeling, which does not contribute to the incremental growth of the

mandible”

*The actual path of the mand condyle is accompanied by selective remodeling & thus neutralizes the growth

* Results in selective enlargement of the mandible, apart & distinct from mechanisms that have been described in the

literature www.indiandentalacademy.com

Counterbalancing proportion

Defined as the percentage of condylar incremental growth, detected by implants that has contributed to the enlargement of the condylion- pogonion dimension

• The quantification & comparison of condylar growth & mandibular enlargement


Counterbalancing =Counterbalancing = proportionproportion

Growth of articulare to pogonionGrowth of articulare to pogonion

Condylar incremental growthCondylar incremental growth×100×100

Mandibular growth =pg-Ar2 – Mandibular growth =pg-Ar2 –

Pg-Ar1Pg-Ar1

Condylar growth – Ar1 – Ar2Condylar growth – Ar1 – Ar2


• According to the concept of congruous mandibular growth, the proportion expected is 100%.

• But the proportion ranges from 50% to 97%.

• Average counterbalancing proportion for Angle classes Class III – 85% Class I – 76% Class II Div 2 – 59% Class II Div 1– 65.5%

Effective contribution vary among individuals because of varying condylar directions & mand remodeling


Concepts of mandibular Rotations


Enlow’s concept

Two categories of Rotations

- Remodeling Rotations

- Displacement Rotations


Remodeling


Ramus • Ramus undergoes remodeling to carryout

following functions

• Place the corpus in constant functional relationship with maxillary arch

• To bridge the pharyngeal compartment

• To accommodate the vertical dimension of nasomaxillary complex

• Give attachment to the growing masticatory musculature. www.indiandentalacademy.com


Vertical lengthening ramus continues after horizontal growth ceases


Opening and closing of the gonial angle compensates for extreme forward or backward rotation


• Vertical growth changes of the mandibular dento-alveolar arch, the ramus & middle cranialfossae must match nasomaxillary growth to achieve facial balance

• Any diff will lead to Displacement mand Rotations


Displacement rotations

• Changes in the junctional contact with the cranial floor and maxilla.

• Cranial base angle-

Open-downward and backward rotation of mandible.

Closed-forward rotation.



Open AngleClosed Angle


Vertically short midface causes forward rotation & upward inclination of mandible


Long nasomaxillary region causes downward

& backward alignment of mandible


Schudy’s concept

• The Rotation of the mandible resulting from an inhormony b/n vertical growth & horizontal growth

• Counter clockwise Rotation - deficiency of vertical growth compared to

horizontal growth & tends to cause closed bite

• Clockwise Rotation – excessive vertical growth compared to horizontal growth & tends to cause open bite




Vertical elements of growth

• Growth at nasion

• Growth of maxillary corpus

• Growth of max post alveolar processes

• Growth of mand post alveolar processes


Posterior growth analysis

A= I+ II + III

The ratio b/n horizontal growth & Vertical growth


Bjork concept


Forward Rotation – 3 Types

Type – I

Center- TMJ

Deep bite

↓ Ant facial height

Lower dental arch compressed in to upper

Cause-occlusal imbalance due to loss of teeth/powerful musculature


• Type II• Center- incisal edges of lower ant teeth

• Marked development of post facial height & normal ↑ ant facial height

• ↑ Post facial height

Lowering of middle cranial fossae

increase in height of ramus


Vertical direction of the condylar growth lowered the mandible more than it is carried forward

Muscular & ligamentus attachments Carries the lowered mandible forward

Lower border undergoes characteristic remodeling


Type III

Center of rotation - premolars

The dental arches compressed in to each other & basal deep bite develops

Cause – Anomalous occlusion of ant teeth


• The inclination of teeth is greatly influenced by rotation of jaws

• Displaces the path of eruption of teeth in mesial direction

• Ant crowding referred as packing


Backward Rotation –two TypesType I

Center - TMJ

Causes- the middle Cranial fossae is rised

-Incomplete development in height of middle cranial fossae as in oxycephaly

underdevelopment of post facial height leads to Backward Rotation


Type II

• Center – Most distal occluding molars

• Cause - Sagittal growth direction of condyle

• The symphysis is swung backwards & chin drawn back

• Double chin


Basal open bite develops

Lower ant teeth retroclined & alveolar prognathism is reduced

Rotation did not lie in the over eruption of lower teeth

This type of rotation is characteristic in condylar hypoplasia & In condylar aplasia


Mandibular growth Rotation is closely associated with both the direction & the amount of growth at the condyles



Maxillary Rotations


Bjork & Skieller

Implant studies of Bjork & Skieller have shown that, The downward & forward displacement of maxillae are associated with varying degrees of vertical Rotation

Internal Rotation produced with in the core of maxilla tends to be masked by surface changes & alterations in the rate of teeth eruption


• The maxilla is less easy to delude in to core of bone & functional processes

• Alveolar process is functional process but no areas of muscle attachment


• Lateral implants – 4yrs of age, inserted in the zygomatic process two on each side, antly on the lower margin away from the crest

•Indicates increase in width of median suture at the level of first molars


• Anterior implants – 10yrs of age, inserted below the anterior nasal spine on each side of median suture at the level of apices of central incisors


• Maxillary Rotations studied in 2 planes

Transverse plane

Vertical plane


Transverse / Mutual Rotation of two Maxillae

Triangle is constructed with the sides of constant length by joining ant & lateral implants


• Lateral implants separate more than ant implants

• Two maxillae rotate in relation to each other in transverse plane

• Length of the maxilla is reduced in mid sagittal plane

• Length of dental arch becomes reduced



Vertical Rotation

A line from tip of ant implant toLateral implant is drawn on profile radiograph

Tracings shows change in inclination of implant line to the SN plane at diff ages


The inclination of nasal floor to ant cranial base is maintained by differential remodeling

In forward rotation – theresorption at nasal flooris greater antly than postly

Facial growth is greater postly


In backward Rotation - Rotates downwards & backwards

Resorption at nasal floor is greater postly

Facial growth is greater antly than postly



Enlow’s

Maxillary Rotations

Displacement Remodeling


Displacement Rotations

Primary displacement

The whole nasomaxillary complex is displaced in conjunction with its own growth


Secondary Displacement

- Results from growth of other bones & their soft tissues


• Displacement in clockwise/counterclockwise direction would result in canting & misfit of the palate & maxillary arch in to either open / closed bite positions

• Remodeling fields along nasal & oral sides of the palate offset & compensate


Remodeling


2-3 – primary displacement

1-2 - Remodeling movement


Prediction of mandibular growth Rotation

Bjork method

• Longitudinal method

• Metric method

• Structural method


Longitudinal method

• The course of development in annual x-ray Cephalometric films

• Superimposed on natural reference strs


Rotation – angle b/n SN lines


Limitations

Pattern of growth is not constant

• permits observation of changes only in sagittal direction

• Changes in vertical direction are masked to larger extent


Metric method

• Prediction of facial development on basis of facial morphology ,determined from a single x-ray

• Statistical studies – predicting the intensity & direction of development from shape & size at childhood is not feasible

• The changes in shape of face during adolescence weakly correlated with shape of face at 12yrs


Structural method

• Based on information gained from implant studies of mandibular remodeling process

• Recognizes specific structural signs develop as a result of remodeling

• Various types of rotations can be recognized with implant method


Structural signs

• Seven structural signs of extreme growth rotation

• Considered in relation to condylar growth direction

• Greater the number, more reliable the prediction will be.

• Signs are not clearly developed before puberty


• Inclination of condylar head

• Curvature of the mandibular canal • The shape of the lower border of the mandible

• Inclination of the symphysis

• Interincisal angle

• Interpremolar and molar angles • Lower anterior face heightwww.indiandentalacademy.com



Condylar Inclination


Mandibular Canal


Lower Border & Inclination of Symphysis


Inter Incisal Inclination


Inter Molar Relation


Condylar Inclination


Mandibular Canal


Lower Border & Inclination of Symphysis


Inter Incisal Inclination


Inter Molar Relation


• But Baumrind & Rodney lee contradicted findings of Bjork et al very strongly


• The study conducted in our Department by violet barbosa,

• Lower gonial angle

• Inclination of condylar head

• Inclination of symphysis are reliable signs to predict the type of rotation

• Limited extent


Interaction b/n Rotation & Tooth eruption

• Rotational pattern greatly influences the magnitude & direction of eruption

• Superimposition on mand lower border- no change in incisor eruption


Forward Rotation

• Superimposition on implants – forward directed path of eruption

• Forward migration of whole dentition

• Anterior crowding

• Lower post teeth- more upright

• Increase in interpremolar & intermolar angles www.indiandentalacademy.com

Average values:Mandibular archMean forward migration of mandibular molars - 5.2mm.Lower central incisors-3.2mm.Shortening of the dental arch-2.0mm.


Average values:• Maxillary arch

-Mesial migration I molars-5mm

-central incisors-2.5mm

Shortening of arch-1mm+1.5mm


Backward Rotation

• Incisors become retroclined

• Alv prognathism is reduced

• Eruption of lower molars – hindered

• Interpremolar& intermolar angles are small


• Proffit

-The lower mandibular teeth erupt in upward and forward direction.

-Forward rotation –alters the path of eruption-directed posteriorly.


Clinical implications

Forward Rotation

• Short face type• “Square jaw” type• Low mandibular plane angle• Skeletal anterior deep bite• Crowding of anterior teeth• Palatal plane is nearly

horizontal. • smile - lower incisors are

visible with the upper incisors hidden behind the upper lip.


Backward Rotation• Long face type• “Round jaw” type• Steep mandibular plane

angle• Skeletal anterior open

bite• Dental protrusion• Negative inclination of

palatal plane


• Various combinations of rotations can cause malocclusions



• Hypodivergent - can compensate for class II - worsen class III

Hyperdivergent - worsen class II

- compensate for class III

Growth Rotation can also affect sagittally


Treatment in preadolescent children

Growth modification-Vertical, sagittal, transverse

Before adolescent growth spurt ends


• Both forward & Backward rotation greatly influences paths of eruption

• Serious risk of extreme migration after extractions

• Extractions should be avoided until the beginning of pubertal growth spurt


• Forward Rotation

• Major risk of deep bite developing- prevented stabilizing appliance introduced before puberty

• After treatment, stabilization is necessary until the growth of the jaws is completed


• Mandibular deficiency• Functional appliances • Removable appliances Activator, Bionator, Frankel 1&2 Bimler’s appliance, Twin block appliance

• Fixed Herbst appliance, Jasper jumper, Churro

jumper,Forsus


Mandibular excess

Functional appliances

Frankel 3

Reverse Activator


MANDIBULAR EXCESS

• extra oral force• orthopedic chin cup• occipital pull chin cup

vertical pull chin cup

Steep mandibular plane angle & excessive lower facial height.


ADULTS

BILATERAL SAGITTAL SPLIT OSTEOTOMY

SET BACK ADVANCEMENT


Maxillary deficiency

• Growth modulation in

sagittal plane can be done :

1.face mask

2.reverse functional

appliances.

Delaire facemask

Petite facemaskwww.indiandentalacademy.com

Maxillary excess

• To restrict the maxillary growth

Headgear


Cervical head gear:

used in patients with horizontal growth pattern with reduced lower facial height.


Occipital pull Head gear:-

Used in long face patients with high mandibular plane angle.


References • Contemporary orthodontics

- William.R.Proffit(2nd &3rd ed.)

• Essentials of of facial growth

- Donald.H.Enlow.

• Dentofacial orthopaedics with functional appliances

-Thomas M.Graber, Thomas Rakosi, Alexandrer G.Petrovic.


• Facial growth and facial orthopedics.

-van der Linden.

• Determinants of mandibular form & growth (CFGS) Monograph-4

• Factors effecting growth of the midface (CFGS) Monogrph-6.

• The rotation of mandible resulting from growth;Its implications in orthodontic treament -F.F.Schudy-AO 1965.no.1,36-50.


• Prediction of growth rotation - A.Bjork-AJO-DO-1969,jun 39-53.

• Facial development and tooth eruption :an implant study at the age of puberty-A.Bjork,V.Skieller AJO-DO 1972,62,4;339-383.

• Normal and abnormal growth of mandible.a synthesis of longitudinal cephalometric implant studies over a period of 25 years.A.Bjork,V.Skieller.EJO-1983,5;1-46.


• The puzzle of growth rotation. J.M.H.Dibbets –AJO-DO June 1985 ,87,6;473-480.

• Mandibular rotations – concepts & terminology

Beni Solow & William Houston J B-EJO-1988,10;177-179.

• Mandibular rotation and enlargement. J.M.H.Dibbets.AJO-DO July 1990,29-32.

• Mandibular morphologic characteristics in relation to various facial types and jaw rotations.- Dr. Violet Barbosa Aug 1996. www.indiandentalacademy.com

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Growth rotations /certified fixed orthodontic courses by Indian dental academy