Growth prediction

GROWTH PREDICTION
Dr.Tinet Mary Augustine. BDS,MDS
Pediatric Dentist
Dr.Tinet’s Pedorayz, Pediatric And Early Age Orthodontic Dental Clinic
DR.TINET MARY AUGUSTINE.BDS.MDS 1

CONTENTS
• DEFENITION
• NEED FOR GROWTH PREDICTION
• DIFFERENT METHODS OF PREDICTION
• HUNTERIAN CONCEPT
• GNOMIC GROWTH AND LOGARTHMIC SPIRAL
• ARCIAL GROWTH
• MOORREES MESH
• JOHNSTONS GRID
• TODDS EQUATION
• VISUAL TREATMENT OBJECTIVE
• CONCLUSION

WHAT?
• Forecast Of Growth Related Changes With The Objective
Of Predicting The Direction And Amount Of Growth Of
The Maxilla And Particularly Mandible As Well As The
Timing Of The Adolescent Growth Period (PROFFIT)

WHY?
• Helps clinician to intercept and correct malocclusion
• Aid for patient education and motivation
• Tool for orthodontic treatment
• Response to a particular treatment can be predicted
• Planning of retension period if the treatment complete s
before the growth finish

METHODS
• THEORETICAL
• REGRESSION
• EXPERIMENTAL
• TIME SERIES

HOW
MANUAL PREDICTION
OR
COMPUTER PREDICTION
CEPHALOMETRIC METHODS
OR
NON CEPHALOMETRIC METHOD

HUNTERIAN CONCEPT

BJORK ROTATION

GNOMIC GROWTH
• Moss and Salentejin

LOGARITHMIC SPIRAL

• Equation of spirals
• Log r = log a +ko
• R=radius of the curve of the spiral
• 0=angulation of the radial line(in radian)
• A=value of r when o=0
• As bone increases in size,the spiral itself doesn’t
change,instead the mandible changes in position and the
base appears to rotate along the spiral

ARCIAL GROWTH
Principle:a Normal Human Mandible Grows Superior Anterior
Position At The Curve Or Arch Which Is A Segment From A Circle
• The radius of circle is determined by using the distance from
mental protuberance to a point at the forking of the stress lines
at the terminal pad of oblique ridge on the medial side of the
ramus(point Eva)

LANDMARKS
• To locate the central core (immune to remodelling)
introduced x1 and point Eva
• x1 represent the entrance of the neurotrophic bundle into
the mandible. And mostly at level of occlusion
• Eva

EVA
• Stress line on Medial surface fork into 2 at Eva

• Dc-midpoint/bisecting point of condylar neck
• Pm /supra pogonion-symphysis from convex to concave
• Mu point-point in sigmoid notch where Eva touch notch
• True radius-it is the intersection of arc from Eva and Pm
• Dc-xi-condylar axis
• Xi-pm-corpus axis
• Dc –xi+xi-pm=core of mandible(path of mandibular nerve)

• Arcial growth was constructed using superimposing serial
lat.ceph and interprete using computer analysis
• Superimposing on corpus axis,registering in PM point,
revealed a mandibular growth pattern in which ramus
found to curve superiorly and anteriorly

ARC A
• Dc-xi-pm
• If growth is in this curve-open gonial angle too wide,resulting
mandible will be obtuse (normally does not happened)

ARC B
• Tip of coronoid-ant ramus-pm point
• Mandibular growth will bend too much

ARC C(arc of mandible)
• Curve between coronoid and condylar process-eva-pm
• Annual increment of around 2.5mmin this curve co-relate
with final composite of computer analysis

Synthesis
• Growing the mandible on this arc, forecasting technique can be done
• Greater the magnitude of growth-greater will be the bending
• Form and size was predicted for 5 years and compared:
• Coronoid and condylar grow upward and outward essentially as a function
of curve
• Gonial angle drifted posteriorly on the arc
• Annual increase of 2.5 mm observed in mandibular growth. Angle
increases with age ie 0.3 per year
• Found to cease by 14.5 females and 19 for males
•

Occlusal plane and tooth eruption
• As mandible grow in arc-space is created for molars
• Arcial growth+eruption of teeh=push chin beneath lower arch(chin
button)
• Angle of corpus axis and occlusal plane remain constant
• If molars restrains from from moving forward,there will be impaction

VALUES
• Condyle Grows At An Avetrage Of 0.2mm Per Year
• Coronoid-0.8mm Per Year
• Symphysis -1mm Per Year
• Gonion-0.2mm Per Year In Males
• Oblique Ridge Grows At An Average Of 0.4mm Per Year

ADVANTAGE
• Arc Of Growth Can Be Constructed For Every Individual
Depending On The The Length Of The Core Of The
Mandible
• Improved Visualisation Of Condyle And Cornoid By
Laminography enabled Rickettes To Better Observe The
Bending Of Mandible From Infancy To Maturity

DRAWBACK
• Depends on operators skill in tracing the cephalogram
• Consideration if the age by chronological method rather
than skeltal method( mitchell and jordan)
• As a average growth increment are added to the age :if
the patient has completed growth or if he is in growth
spurt or lag phase,it will alter the result

MOORREES MESH
• Moorrees constructed a template in the form of a mesh which
was used to superimpose growth changes in serial lateral
cephalometric radiograph
• Represent the shape of the upper face in terms of facial
depth(N-S) and facial height(N-ANS)

• Vertical N-ANS(1-5)
• Every Line Corresponds To Specific Landmark
• Represents Facial Depth And Facial Height

• Horizontal-perpendicular to vertical(A-G)

PREDICTION
1. Comparison of individual depend on size of core rectangle
2. facial type remain constant and size increase (8-16 years
of all individual) with median increment of
• height as 4.5mm in boys and 3.5mm in girls
• length as 3.2mm in boys and 2.4mm in girls

At 16-
• tip of nose,pogonion,symphysis are forwardly placed
• position of incisors not changed
• pterygomaxillary fissure descent with maxilla
• sella ascends,basion descend
• lengthening of ramus
Facial profile remain same
Differential in growth increments are responsible for the rotation of the
mandible and its forward translation(skiller)

Trends in growth
• Average horizontal change-10% in boys
-8% in girls
• vertical change-1%downward in boys
-5%upward in girls
Orthognathous face remains straight
Retrognathic mandible-posterior distortion of rectangle
High mandibular angle –downward displacement of mesh

JOHNSTONS GRID
• Show average increment of growth per year for nasion(n) /
subnasale(A)/Supramental(B) / any point on maxillary first
molar(M) / posterior nasal spine(P)

Cranial superimposition
• SN –REFERENCE PLANE
• INDIVIDUAL VARIATION CAN BE STUDIED

Regional superimposition
• Age/sex of the patient is noted
• Regional template is placed over the cephalogram
• measurement is done made between 2 points like PNS-
ANS (max) GO-PG (man)

PREDICTION
• Every part of the skeltal frame work is in the form of a grid
(maxilla/mandible)
The forecast grid system was constructed on the assumption
that growth changes are regular and annual changes and
direction of growth is average
Every point is advanced one grid unit per year superimposed on
SN registered at S

Uses of template
• To compare the growth of jaws
• Vertical growth can be assessed
• Position of upper and lower incisor can be directly seen
• Deviation from individual part can be assessed
• Can differentiate between skeltanal and dental cause of
maiocclusion

TODDS EQUATION
• Predicted the angular co ordinate of landmarks
• Biomechanical influences on growth and the external influence
of the enviornment(gravity) are considered
• P=a R (1-cos0)
• A-constant representing product of gravity and density of fluid
• The direction of pressure is normally perpendicular to the
surface at every point

Concept
• If all bone elements were displaced in the direction of
gravitational pressure,then they would all move outward
along radial line emenating from the center of the sphere

• Defects
• Heads are not perfectly spherical
• There are other sources of stresses along with the gravity,
neural developments,oral habits,facial postures and
expressions
• Merit
• This is helpful to appreciate the global influence on
cranifacial growth

VISUAL TREATMENT OBJECTIVE
• “What is hoped than what is likely to happen”
• Visual plan to forecast the normal growth of the patient
and the anticipated influence of treatment to establish the
individual objective we want to achieve for patient

• Helps to predict the treatment outcome
• Vto permit development of alternative treatment plan
• Can decide how far mechanics should be extended to
achive his goal
• Helps to moniter progress during treatment
• Deviation from the expected progress can be recognized
and can be instituted early
• Patient education and motivation

Advantages
• Child
• VTO incorporates the expected growth or any growth
changes induced by treatment
• skeltally normal child-to understant amount of tooth
movement needed for the correction of malocclusion
• With skeltal deformity- gives a picture of the uncertainity
of both growth pattern and response of treatment

Adolescent and adult
• little groeth is remaining so predicting treatment effects
are easier and more reliable
Dentist
• Helps to improve the treatment by setting in advance and
can do comparison of results with the expected outcome
• Gives an idea about the areas in which treatment could
be improved

VISUAL TREATMENT OBJECTIVE
FRANKEL METHOD

HOLDAWAYS METHOD

STEP 1
• TRACING FRONTONASAL AREA(ba-n n-a)

STEP 2
• Express The Growth In Frontonasal Area In 2 Years
• Move 1.5mm
• Draw rickettes facial axis

STEP 3
• To Express Growth In Vertical Direction In The Mandible
• Anterior portion of mandible, down mand.plane
• VTO up
• Expected-3mm per year

STEP 4
• To Express Horizontal Direction In Mandible
• VTO forward
• Vertical height can be predicted

STEP 5
• To Locate And Draw The Maxilla And Lower Half Of The Nose
• VTO up on NA line untill growth 40 %above BA and 60% below
mandible
• Trace maxilla-PNS-ANS-3mm below ANS
• Trace nose

STEP 6
• TO LOCATE AND DRAW THE OCCLUSAL PLANE
• VTO in NA line- vertical growth 50%
• Trace occlusal plane-3mm above lip embrassure

STEP 7
• TO DETERMINE THE SOFT TISSUE LIP CONTOUR
• Harmony line-upper sulcus 5mm-adjust to 3-3.5mm
• VTO in NA line- lip compare by template

STEP 8
• REPOSITION OF UPPER INCISOR
• IT IS DETERMINED BY LIP STRAIN
• UPPER LIP CHANGE
• MAXILLARY INCISOR REBOUND(1.5MM)
• Superimpose at NA

STEP 9
lower incisor position
VTO in mandibular plane/occlusal plane as guidance
• Lower Incisor Position in harmony with upper
• Total Discrepancy=(2xlower Incisor Movement)
+Crowding(model Analysis)

Step 10
• Reposition of lower first molar after repositioning of
incisors
• Extraction-molar forward
• Mild discrepancy-molar tipped back to check non
extraction

Step 11
Upper molar position in accordace with lower
NA and maxilla as guide plane

Step 12
• Complete artwork
• Point A , Anterior portion of hard palate,Lower alveolus

RICKETTES VTO METHOD
• Cephalometric method
• He divided as
• Cranial base prediction
• Mandibular growth prediction
• Maxillary growth prediction
• Occlusal plane position
• Location of dentition
• Soft tissue of face

Cranial base
• Superimpose on Ba-N
• Grow nasion 1mm /year for 2 year
• Basion also grown 1mm/year
• Slide to coincide old and new nasion-trace nasion area
• Similarly the basion area

Mandibular prediction
• Trace Ba-N line register
• Plane is rotated up and down to close and open the bite
at N using DC fulcrum
• Draw condylar axis,coronoid and condyle

Condylar and corpus axis growth
Condylar
• Mark 1mm /year down DC
• Slide condylar axis so that new mark is on Ba-N
• Extend Xi and mark Xi new
Corpus
Superimpose old and new Xi ,the increment at PM is 2mm/yr
Marking Pm new trace posterior and lower border of mandible
Slide back along corpus axis superimposing Pm
Trace symphysis and mandibular plane
Draw new facial palne(N-Pg)

Mandibular growth
• Changes with every treatment
• Calculated as degree of opening or closing of facial axis.
• Facial axis opens 1 degree with growth
Convexity reduction -facial axis opens 1degree/5mm
Molar correction -1degree/3mm
Overbite reduction -1degree/4mm
Crossbite correction -1-1 ½ degree ,recovers half the distance

Maxillary growth
• With normal growth point A moves 0.8 mm forward but
with treatments the changes are as follows

Occlusal plane
• For each distal movement of point A occlusal plane will
drop down by ½ mm
• Superimpose mark on the old menton and facial
plane,parallel the mandibular planes by rotating at menton
• Thus occlusal plane can be constructed

Dentition
• LOWER INCISOR
Determined by arch length
Dot is placed 1mm above occlusal plane and 1mm ahead of A –
Pg . Draw lower incisor in ideal relation to A Pg line and occlusal
plane
• UPPER INCISOR
drawn in good overjet and overbite(2.5mm) relation to
lower incisor. Interincisal angle maintained at 130 degree

• LOWER MOLAR
• Without treatment-lower molar will erupt directly towards
the occlusal plane
• With treatment molar might move forward and for every
1mm forward movement decrese arch length by 2mm
• Movement of lower molar depend on lower incisor
• UPPER MOLAR
• Upper molar is drawn to class 1 with lower molar

CONCLUSION
• Growth prediction methods can be used as a short term
forecast to plan strategy and long term forecast to give
evaluation of final result and to analyze esthetic and facial
balance of an individual.
• A knowledge about the growth prediction will hlelp the
dentist in planning proper orthopedic treatments.

Thank you

REFERENCE
• Bjork A. Prediction of mandibular growth rotation. AJO 1969;39-53.
• Jacobson A. Radiographic cephalometry, from basics to video
imaging.
• Johnston LE. Template analysis. JCO. 1987;585-90.
• Moorrees CFA, Lebret L. The mesh diagram and cephalometrics. AO
1962;32:214-31.
• Moss ML, Salentijin, Herbert P. The logarithmic properties of active
and passive mandibular growth. AJO 1974;66: 64564.
• Ricketts RM. A principle of arcial growth of the mandible. AO
1972;42:368-86.
• Thompson D’ Arcy W. On growth and form. Cambridge Univ Press;
1961
• GrowthSridhar Premkumar,Textbook Of growth and Craniofacial
Development
• Vander Linden,development Of Dentition

Growth prediction

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