Growth prediction 2 /certified fixed orthodontic courses by Indian dental academy

GROWTH PREDICTIONS

INDIAN DENTAL ACADEMY
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Holdaway’s soft-tissue VTO
• Purpose is to establish a balanced profile and
pleasing facial esthetics and to evaluate the
orthodontic correction necessary to achieve this
goal
• Holdaway VTO emphasizes soft tissue profile
balance


• Growth of the cranio-facial skeleton is predicted for
the estimated treatment time, and the soft tissue
profile between the nose and the chin arranged to
create an “ideal” facial profile for the individual
patient
• Maxillary and mandibular incisors are repositioned
to eliminate lip strain
• Allowance is made for probable post treatment
“incisor rebound”
• Maxillary teeth are positioned first, and then lower
incisors are repositioned to be in harmony with the
upper incisors

• Following the repositioning of the mandibular
incisors, the resultant arch length discrepancy
may be calculated to determine whether or not
teeth should be extracted


• The VTO is thus a dynamic cephalometric
analysis which takes into account both growth
and biomechanics, thus achieving its aim of
being a Visualized Treatment Objective
• It outlines a goal from the inception of
treatment and may be usefully employed in
monitoring growth and treatment progress


• In sum, therefore the VTO accomplishes :
Predicts growth over an estimated treatment time,
based on the individual morphogenetic pattern
Analyzes the soft tissue facial profile
Graphically plans the best soft tissue facial profile
for the particular patient
Determines favorable incisor repositioning, based on
an “ideal” projected soft tissue facial profile


Assists in determining total arch length
discrepancy when taking into account
“cephalometric correction”
Aids in determining between extraction and
nonextraction treatment
Aids in deciding which teeth to extract
Assists in planning treatment mechanics
Surgery vs. non-surgery
It provides a visual goal or objective for which to
strive during treatment

OJECTIVE : To draw frontonasal area, line
BaN and line NA


OBJECTIVE : To express growth in the frontonasal
area over a two-year period
Super impose on line BaN and move the VTO until
there is 1.5 mm growth in the fronto nasal area
Holding the VTO tracing in the position copy the
Ricketts facial axis

OBJECTIVE : To express growth in a vertical
direction in the mandible, and to draw the anterior
portion of the mandible, soft tissue chin and the
mandibular plane of Downs
Superimpose the VTO facial axis along the original facial axis.
Move the VTO tracing upwards so that the VTO BaN line is
above the original BaN line, the distance between these lines
should be three times the amount of growth expressed in the
frontonasal area

OBJECTIVE : To express growth in a horizontal direction in
the mandible and draw the posterior border of the mandible
Move the VTO forward until the original and VTO foramen
rotundae are vertically aligned


OBJECTIVE : To locate and draw the maxilla, and
lower half of the nose
Super impose the VTO NA line on the original NA
line and move the VTO up until the vertical growth is
expressed above the BaN line and below the
mandibular plane is in the ratio of 40:60

OBJECTIVE : To locate and draw the occlusal plane
With the VTO superimposed on line NA, move the VTO
tracing so that the vertical growth between the maxilla and the
mandible is expressed as being 50% above the maxilla and
50% below the mandible

OBJECTIVE : TO determine the soft tissue lip
contour using the Holdaway line


OBJECTIVE : to reposition lower incisor and calculate
resultant arch length change
judge the position of the lower incisor
To calculate lower arch length change, superimpose tracing
on mandibular plane and register on symphysis. Measure the
distance between old and new incisor position and double this
measurement to determine total arch length discrepancy

OBJECTIVE : To reposition lower first molar, use the plaster
casts to determine arch length discrepancy due to crowding
and/or rotation.


OBJECTIVE : To reposition maxillary first molar
Using the occlusal plane and lower first molar as a guide draw
the maxillary first molar in good Class I occlusion with the
lower first molar


OBJECTIVE : To complete art work
ANS to upper incisor
Anterior portion of hard palate
Lower alveolus lingually and labially


A statistical evaluation of the
Ricketts and Johnston growthforecasting methods


• Four methods of growth forecasting were compared
– Johnston forecast grid
– Ave. increments from sella-nasion
– Ricketts short-range prediction
– Computer forecast
• Objective was to predict the final position of the
points A, Pogonion, end of the nose, lower molar
and point Xi with respect to cranial reference lines


• The Johnston forecast
grid


• Errors were squared, summed, and divided by
the number in the sample to get the meansquare error. Square root was taken for the rotmean-squared error
• 70% of the predictions will be within ±1 rms
error
• 95 % will be within ±2 rms error


• Ave. increments from sella-nasion
To study points not included in Johnston
forecast grid, as well as grid’s applicability to a 10year growth period
Average increments for each of the points under
consideration were calculated from SN with S as
the origin, and these increments were then used
in a prediction as follows: Using sella-nasion as a
horizontal axis with sella as its center, ave.
increments per year were added


• Girls - 15 years
• Boys - 19 years


• The Ricketts shortrange prediction


• Computer forecast
Individual growth curves are used for the mandible,
maxilla, and cranial base rather than using the same
increments for every age group
Abnormal growth with RMDS data bank


Patients who grow abnormally large mandibles with less
growth in the cranial base – abnormal Class III patterns


Unusually strong patterns which rotate forward


Abnormally weak facial patterns – they rotate distally


Results
Johnston grid
Least accurate
It was accurate as any for predicting the nose
64 percent accurate for Point A
70 percent accurate on Pogonion


S-N average increments
Improvement over the Johnston grid at both
Pogonion and point A


Ricketts short-range prediction method
Less rms error than Johnston grid or SN average increments
Some of the smaller over-all error was due to the fact that
point CC, the origin of this growth prediction, is closer to
Pogonion than to Sella
10 to 20 percent improvement of this method over average
increments


RMDS computer program
Based on theories of Ricketts
Individualized further by using growth rates variable for the
patient’s age and by recognising unusual facial patterns
Most accurate of the four methods

 21% more accurate than Ricketts
 56% more accurate than Johnston grid


Prediction of abnormal growth in
Class III malocclusions
If the actual growth was far different from the
predicted growth, the records were often returned to
the laboratory so that a file of “abnormal growth “
could be compiled
A consistent type emerged – one which grew more in
the mandible and less in the cranial base than predicted


• The three most consistent measurements which
deviated from the normal in these patients were
ramus position, porion location and cranial
deflection
• Predictor measurements
• Hokkaido University Orthodontic Department


• For cranial deflection, porion location and
ramus position the greater the value, the more
likely the patient is hypothesized to have a Class
III growth pattern
• With molar relation, the lesser the value, the
more likely the patient is to have a Class III
malocclusion


Clinical norm
(CN)
Cranial deflection 28
Ramus position
75.5
Porion location
37
Molar relation
-3.0


Standard
Deviation
3.0
2.8
2.5
2.6

Amount of abnormality, or deviation is calculated
by :
V-CN
SD


Evaluation of Ricketts’ long-range growth
prediction in Turkish children
• Cephalometric analysis was conducted at baseline and 7
years for 40 children (20 girls, 20 boys) who received no
orthodontic treatment. Ricketts’ long-range prediction
was performed from baseline cephalograms and
compared with actual growth 7 years later. Twenty-one
cephalometric (12 angular and 9 linear) parameters were
measured on actual and predicted tracings. The Pearson
correlation coefficient was used to evaluate
relationships between the “predicted” and “actual”
measurements.
• There was a higher level of correlation for growth
prediction in girls

• The baseline average age was 9.2 ± 0.82 years for girls
and 9.3 ± 0.92 years for boys
• Linear measurements: 1, Convexity; 2, Condylion-Point
A; 3, Condylion-Gnathion; 4, Lower lip to E plane; 5,
Upper lip length; 6, Cranial length (anterior) (CC-Na);
7, Ramus height (CF-Go); 8, Porion to PTV; 9, Corpus
length (Xi-Pm).
• Angular measurements: 1, Lower face height; 2,
Nasolabial angle; 3, Facial depth; 4, Facial axis; 5,
Maxillary depth; 6, Maxillary height; 7, Palatal plane-FH
plane; 8, Mandibular plane-FH plane; 9, BNA angle; 10,
Cranial deflection; 11, Ramus-Xi position; 12,
Mandibular arc angle.

Ricketts’ long-range growth prediction applied to
Turkish children showed statistically significantly higher
correlations between predicted and actual
measurements in:
• Convexity, lower face height, condylion, point A, upper
lip length, facial depth, facial axis, palatal plane-FH
plane angle, mandibular plane-FH plane angle, ramus
height, and mandibular arc angle in girls
• Lower face height, nasolabial angle, porion to PTV,
ramus-Xi position, cranial deflection, condylion-point
A, lower lip-E plane, facial axis, BNA angle, and
mandibular arc angle in boys.

Thank you
Leader in continuing dental education


Growth prediction 2 /certified fixed orthodontic courses by Indian dental academy

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