Growth rotations /certified fixed orthodontic courses by Indian dental academy

Growth Rotations

www.indiandentalacademy.com

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INDIAN DENTAL ACADEMY
Leader in continuing dental education


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 Introduction
 Maxillary rotations
 Prediction of growth rotation
 Growth rotations- facial development,
tooth eruption
 Clinical implications

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Introduction
 Facial growth in terms of rotations is
important in the understanding of the
development of the craniofacial complex.
 The introduction of the implant method by
Bjork (1955)made it possible to study the
rotations of the maxilla and mandible.


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MAXILLARY ROTATIONS
 Less easy to divide maxilla into a core of bone
and a series of functional processes.
 There are no areas of muscle attachment
analogous to those of the mandible.
 Implants placed above the maxillary alveolar
process show that the core of the maxilla
undergoes a small degree of rotation

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ENLOW’S CONCEPT

Maxillary Rotations

Displacement

Remodeling


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Displacement
 Primary displacement occurs-antroinferior
direction.
 Sutures are tension adapted-cannot grow by
pushing-apart.
 Stimulus for sutural remodeling is due to the
displacement.


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 Secondary displacement-


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Growth of the brainSpinal cord aligns
vertically.
Orbits rotate and align so
that they point forward.
This plane determines the
direction of nasomaxillary
development.

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The maxillary
tuberosity located just
below the floor of the
orbit.
The tuberosity is
aligned perpendicular
to neutral geometric
axis of the orbit.


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 The hard palate
conforms to the
alignment of maxillary
nerve before it enters
the orbit.

 The plane projects to
inferior most point in
the occipital fossa.

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Remodeling
 Lacrimal suture: key
growth mediator.
 Sutural system of
lacrimal bone –slippage
for multiple bones.
 The maxilla slides down
along its orbital contacts.
 Lacrimal bone –
remodeling rotation.


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Drift of the teeth
 As the maxilla and mandible enlarge,
dentition drifts-horizontally and vertically.
 The whole tooth and its socket move.


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Nasal and palatal
remodeling


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 The balance between greater and lesser amounts
of remodeling in the posterior & anterior parts of
the maxilla is the response to clockwise/
counterclockwise rotatory displacement of
middle cranial fossa.
 Compensatory remodeling rotation of the
nasomaxillary complex-sustains its proper
position relative to the neutral orbital axis.
 Remodeling also occurs as bones assume new
positions with expansion of the soft tissue
matrix.

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1-2-direct relocation.
2-3- primary displacement


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BJORK’S CONCEPT
 Longitudinal study done by implant method.
Lateral implants:4yrs of age
-inserted laterally in the zygomatic
process of the maxilla (2 on each side).
-increase in distance between the implants
on the frontal film - increase in the width in the
median suture at the level of the 1st molars.


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Anterior implants:10-11yrs of age
-inserted below the anterior nasal spine.
-one on each side of the median suture at level
with the apices of the central incisors.
- increased distance bw the implants
measured on frontal film - growth in the width
in the median suture at the level of the incisors.


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 Implant line-Tip of 1 anterior implant to midpoint of 2
lateral implants.
-Change in the inclination of implant line to
the S-N line-vertical rotation of maxilla in
relation to cranial base.


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Maxillary growth-Lateral
implants.
 Height

(4 yrs)

-growth at frontal and zygomatic process.
-apposition at lower alveolar process and
eruption of teeth.
-apposition at floor of the orbit.
-nasal floor lowered down.

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 Lateral implants-vertical
component calculated at
right angles to S-N.
 Sutural lowering -11.2mm
 Apposition at the floor of
the orbit-6.4mm.
 Lowering of nasal floor4.6mm
 Appositional growth in
height of alveolar processwww.indiandentalacademy.com
14.6.mm

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 Width
-growth in the median suture.
-appositional remodeling in the outer
aspects.
-Enlow-widening of hard palate mainly
result of remodeling.
-Persson, Melsen-growth in median suture
upto adolescence.


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 Implants study show
-median suture growth-6.7mm
-outer aspect of maxilla-9.5mm
-growth in the median suture follow the same
curve as their growth in body height.


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Growth of maxilla in 3-d anterior and lateral implants(10-11
yrs)
 Length-sutural growth towards palatine bone by
apposition on tuberosities.
-anterior surface was thought to be resorptive;
unchanged when studied using implants.


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Sagittal growth studied in relation to
infrazygomatic crest.


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ROTATIONS
 Transverse plane
 Vertical plane.


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Transverse mutual rotation
of the two maxillae: Joining anterior and lateral implants on each
side a triangle is constructed with sides of
constant length.


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 Lateral implants increased 3mm against 0.9mm
of the anterior implants.
 Thus, the lateral implants separate more.
 This reduces length of maxilla in mid sagittal
plane.
 The distance between 1st molars increases more
than canines


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VERTICAL ROTATIONS
 Superimposition shows parallel lowering
of nasal floor.


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 Implant studies-maxilla undergoes vertical rotation.
-inclination of anterior cranial base to nasal floor
is maintained by compensatory remodeling.
-forward rotation-anterior resorption &
deposition posteriorly.


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 Backward rotation-Rotates down anteriorly.

-posterior resorption more
than anterior.


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Prediction of growth
rotation

 Rotational prediction has been done in various
ways:
-Bjork’s method
-Logarithmic spiral (Moss)
- Arcial growth prediction (Ricketts)mandible rotates in the form of an arc.


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BJORK’S METHOD
 LONGITUDINAL
 METRIC
 STRUCTURAL


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LOGITUDINAL
 Longitudinal method-annual cephalograms.
-natural reference structures.
-rotation can be read from angle formed
between S-N lines of 2 ages.

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1.

Tip of the chin.

2.Inner cortical structure at the
inferior border of the
symphysis.
3. Mandibular canal.
4. Lower contour of molar
germ .


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Limitations :
 The pattern of growth is not constant and
changes by adolescence.

 It permits the observation of changes in the
sagittal jaw relation, but changes in the vertical
jaw relation are masked. Periosteal remodeling
at the lower border masks the actual rotation.


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Metric
 It aims at a prediction of facial development
on the basis of the facial morphology, determined
from single x-ray film.
 Statistical studies show –possibility of predicting
intensity & direction of growth from size and shape
on childhood is not feasible.
 Very weak correlation found between inclination
of mandible at 12years and rotation during
adolescence.

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Structural
 Based on information concerning the remodeling
process gained from implants.
 If implants are not used, single radiograph is
used to predict mandibular rotation.
 Specific structural features develop as a result of
remodeling in a particular type of rotation.


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Structural signs of growth
rotation
 Seven signs-extreme growth rotation.

 Considered in relation to direction of
condylar growth.

 Greater the number-more reliable the
prediction.

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 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 height

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Condylar Inclination


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Mandibular Canal


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Lower Border & Inclination of
Symphysis


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Inter Incisal Inclination


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Inter Molar Relation


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Condylar Inclination


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Mandibular Canal


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Lower Border & Inclination of
Symphysis


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Inter Incisal Inclination


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Inter Molar Relation


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Mandibular morphologic
characteristics in relation to
various facial types and jaw
rotations.- Dr. Violet Barbosa
 Had divided the cases into 3 groups:
Group A- Forward rotation.
Group B- Normal rotation.
Group C-Backward rotation.

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 Index I = S-tgo/ N-Gn x 100
 Lower gonial angle
 Inclination of condylar head
 Shape of lower border of mandible
 Inclination of symphysis
 Interincisal angle
 Intermolar angle
 Depth of antegonial notch


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 Results:
Index I,
Lower gonial angle ,
Inclination of condylar head and
Inclination of symphysis
could be relied upon, to predict the type of rotation of
the mandible to a limited extent.

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Facial pattern and Tooth
eruption

 There is considerable difference in development
and facial form.
 Forward rotation-normal
underdeveloped anterior face height.

excess-

 Backward rotation-overdevelopment of anterior
face height.
 Type of rotation depended on the condylar growth
direction and intensity.
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Tooth eruption
 The rotational pattern influences the magnitude
and direction of tooth eruption.

 Superimposition on lower border of mandible
gives impression-teeth erupting vertical


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 Implants-forward directed path of eruption in
case of forward rotation.
 Forward migration of the entire dentition.
 Molar eruption more than anterior.
 Lower molar teeth more upright than upperincrease in interpremolar and intermolar angles.


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Average values:
 Maxillary arch
-Mesial migration I molars-5mm
-central incisors-2.5mm
Shortening of arch-1mm+1.5mm


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


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 Backward rotation-lower anterior teeth-tipped
backward.
 Reduced alveolar prognathism.
 Molar eruption-diminished.


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 Proffit
-The lower mandibular teeth erupt in upward and
forward direction.
-Forward rotation –alters the path of eruptiondirected posteriorly.


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Clinical implications
Extreme 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.

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Backward rotation Long face type
 “Round jaw” type
 Steep mandibular plane
angle
 Skeletal anterior open
bite
 Dental protrusion
 Negative inclination of
palatal plane


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 Can have various combinations of rotations of
maxilla and mandible.

 Convergence or divergence of jaw bases leads to
various types of malocclusions.


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TREATMENT OF SKELETAL PROBLEMS
IN PREADOLESCENT CHILDREN
GROWTH MODIFICATION
Before the adolescent growth spurt ends


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FUNCTIONAL JAW ORTHOPEDIC APPLIANCES:
MANDIBULAR DEFICIENCY
REMOVABLE:

Activator, Bionator, Frankel 1&2,Bimler’s
appliance & Twin block appliance
FIXED:

Herbst appliance, Jasper jumper

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MANDIBULAR EXCESS:
FUNCTIONAL JAW ORTHOPEDICS
Frankel 3 appliance
Reverse activator


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MANDIBULAR EXCESS
 extra oral force
 orthopedic
chin cup
 occipital pull chin cup
vertical pull chin cup
Steep mandibular plane
angle & excessive lower
facial height.

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ADULTS
BILATERAL SAGITTAL SPLIT OSTEOTOMY

SET BACK

ADVANCEMENT


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Maxillary excess:For restriction of maxillary growth in growing
individuals appliances like
1.Headgear
2.Functional appliances


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Cervical head gear:
used in patients with horizontal growth
pattern with reduced lower facial height.


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Occipital pull Head gear:Used in long face patients with high mandibular
plane angle.


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 Maxillary Deficiency: Growth modulation in
sagittal plane can be done :
1.face mask

Delaire facemask

2.reverse functional
appliances.


Petite facemask

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Combination of maxillary excess and
mandibular deficiency

High pull headgear with functional appliance

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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.

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 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.

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 Prediction of growth rotation - A.Bjork-AJODO-1969,jun 39-53.

 Facial development and tooth eruption :an
implant study at the age of pubertyA.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
81
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-EJO1988,10;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.


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Thank you
Leader in continuing dental education


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Growth rotations /certified fixed orthodontic courses by Indian dental academy

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