Post natal growth of the cranium and jaws

4. At birth the head of the infant is large, due to the advanced
state of the brain. The face forms only one-eighth of the bulk of
the head, whereas in the adult it forms one third to one-half of
the bulk.

5. The infant’s face is relatively much broader and shorter
than that of adult particularly marked below the level of the
orbits.

6. Growth includes the increase in size of all tissues both
hard and soft.
1- by addition of bone tissue to the surface under
the periosteum (appositional growth).
2- by the growth of fibrous tissue or cartilage which
is progressively converted to bone as occurs in sutures,
synchondroses, and the condylar cartilage (interstitial growth).

7. growth of the head, is sub-divided as :
(a)Growth of the cranium:
(i) cranial vault . (ii) cranial base.
(b) Growth of the face:
(i) the upper face . (ii) the mandible.

8. (a) Growth of the Cranium:
(i) the cranial vault ( CALVARIA)
cranium is divided into segments by sutures
which are sufficiently wide to be palpable at birth.
.

19. Concurrently with growth in the sutures, apposition and absorption adjust the shape of
each bone to lessening curvature of the skull as the cranium is enlarged

20. Apposition of bone on the external surface also increases the
thickness of these bones.
The development and extension of the frontal sinuses,
particularly about the age of puberty, accompany rapid additions
of bone to the facial surface of the frontal bone in the superciliary
region.

25. (ii) The cranial base.
The greater wings of the sphenoid and
squamous part of the occipital-bones are
seperated by the wedge- shaped petrous
portions of the temporal bones.
Growth at these obliquely placed sutures contributes to
increases of width and length of the cranium. The suture between
the sphenoid and frontal and ethmoid bones are also important
cranial growth sites up to the age of eight years.

26. Synchondrosis : areas of growing cartilage between individual
bony centers .
Cranial base grows by endochondral ossification
that occurs at both margins of the synchondrosis
Cranial base grows by cartilage growth in the synchondrosis
(sphenoethmoidal, inter-sphenoidal, and spheno- occipital)

27. A) Spheno-ethmoidal synchondrosis:
 Between sphenoid bone and ethmoid bone
 Closes at about 5-7 years

29. C) Spheno-occipital synchondrosis
 in the midline
cranial base
between occipital
and sphenoid bone.
 persists till 18-20
years of age closing
a few years earlier
in girls than boys

30. The spheno-occipital synchondrosis .
The direction of growth is along an axis which is directed
forwards and upwards.
It therefore carries the upper part of the face and the anterior
half of the base o f the cranium bodily
upwards and forwards .
This upward movement is compensated
by downward growth of the face itself.

35. (b) Growth of the face:
It grows in two ways : by sutural growth ( apposition of
bone tissue between the bones ) , And by surface
apposition.
.
Sutural growth Surface apposition

36. The system of sutures that unites the bones of the upper
part of the face to the cranium includes the following sutures :
Fronto- nasal , fronto- maxillary , zygomatico-frontal,
zygomatico-temporal , Zygomatico-maxillary and pterygo-
palatine.

37. Growth at these sutures carries the upper face downwards
and forwards and increases the height of the orbit but not the
infra-nasal height. By the age of seven years the orbits
almost attain their full adult size. After this age, the sutures
may play little part in vertical growth of the face .
.
Quted from : Facial Skeletal Growth and Timing of Surgical Intervention Russell R. Reid,

53. d.
Surface apposition : takes place over most of the facial or
anterior surface of the maxilla. This accompanied by apposition
to the outer surface of the supra-orbital region of the frontal bone.

54. . The forward growth of the maxilla is accompanied by
addition of bone to the anterior surface of zygomatic process.
The latter, however, is relatively slower so that the inferior root
of the zygomatic process (key ridge) occupies first a position
over the second deciduous molar, and later over the roots of
the first permanent molar.

59. .
The alveolar border grows downwards, outwards, and
forwards, carrying the teeth with them. This increase of
height of the alveolar process is accompanied by
additions of bone to the palate though to a lesser extent,
causing an apparent deepening of the palate.

64. The downward growth of the alveolar border is followed by
a downward extension of the maxillary antrum, and the floor
of the nose. As the downward growth of the alveolar process
is more rapid than that of the palate, the floor of the antrum
comes to lie below the level of the inferior meatus of the
nose.

65. The downward and outward growth of the alveolar process
account for the lateral growth of the lower part of the maxilla.
This is followed by resorption of the bone on the inner surface
of the walls of the antrum. The zygomatic arch grows outwards
by addition of bone to its outer surface and resorption on the
inner surface.

66. Growth of the mandible:
At birth the mandible is little more than a curved bar of bone.
The coronoid, angular and alveolar processes are
underdeveloped. At each upper end of the mandible a cap of
cartilage represents the condyle and merges into the ramus.
these two caps are centers from which growth causes an
increase of mandibular length.
The growth here is by surface apposition of cartilage and it
is possible that interstitial growth of cartilage occurs also.

67. Concurrently with extension of the bone upwards,
backwards and outwards, there is moulding of the surface by
resorption and apposition of bone to develop and preserve
the shape of the neck of the condyle. The coronoid process
grows by addition of bone to its posterior surface; there being
resorption at the anterior border as the vertical ramus grows
upwards, backwards and outwards with the condyle. This
contributes also to the length of the alveolar process.
The region of the angle of the mandible is augmented by
addition of bone to the posterior border of the ramus.

68. This apposition decreases the size of the angle made by the
posterior and inferior borders of the mandible from about 175
degree at birth to 115 degree in the adult. A small amount of
growth occurs along the inferior border of the mandible.
Apposition of bone to the lateral and anterior surfaces of the
mandible increases Its thickness. The alveolar process grows
upwards, outwards and forwards by addition of bone to its free
border and, because the anterior border of the ascending ramus
slopes upwards and backwards, the alveolar border increases
in length providing sufficient space for the accomodation of the
permanent teeth.
At birth In old ageIn the adultIn childhood

69. The two halves of the mandible are united by a suture in
the midline. This is closed by about the age of one year.
After this age, lateral growth in anterior part of the mandible
takes place by apposition of bone on the outer surfaces
and a little resorption on the inner surfaces.
The upward and outward growth of the condyles and
growth at the posterior borders of the vertical rami increase
the width of the posterior part of the mandible.

70. The mental foramen during the early years of life is situated
under the first deciduous molar. In the adult it lies below and between
the roots of the first and second premolars.
This change in position of the foramen is due to the backward and
outward inclination of the canal.
As bone is added to the outer surface of the body of the
mandible, the foramen is carried backwards. Also, the upward and
forward growth of the alveolar process carries the teeth forward
relative to the mental foramen.
The inferior dental canal increases in length by addition of bone to its
posterior end, the inferior dental foramen.
Mental foramen in child hood
Mental foramen in adult

83. Late skeletal growth
The jaws and dental arches reach adult proportions at
different times, depending on the dimension considered.
Transverse width is attained first and with the exception of the
tuberosity areas tends to be completed before the adolescent
growth spurt. Growth in length of both jaws continues through
puberty but virtually ceases in girls by 14-15 years of age and
in boys by 18 years.

84. The mandible in particular shows late growth in the teens.
The vertical height of the face and jaws does not reach
adult proportions until later, 17 or 18 years of age in girls
and the early 20s in boys, and is accompanied by a
concomitant eruption of the teeth.

85. facial growth continues
in adult life. There is
little change in width
yet there is a small but
continued expression
of antero-posterior and
especially vertical
patterns of growth.
Changes in the soft
tissue profile are
greater than changes
in the facial skeleton,
these being an
elongation of the nose,
flattening of the lips,
and increasing
prominence of the chin.

87. The pubertal growth spurt :-
On average, the peak of the growth spurt occurs at 12
years in girls and at 14 years in boys.
The growth spurt is a manifestation of
physical maturity. Too much emphasis has
been relied on the relationship of the timing
of the growth spurt to orthodontic treatment.
The relevant question in the treatment of patients where
growth is important is whether or not an appreciable amount of
growth can still be expected.
Where growth would be helpful such as in Class II cases
where a deep overbite has to be reduced and where favourable
growth changes might improve the skeletal pattern, it is
probably best to proceed with treatment as soon as dental
development justifies this.

88. In most cases this will be when the upper permanent canines
are just emerging. If dental development is retarded and the
child has reached the average age of the
peak of the growth spurt, treatment should
be commenced in order at least to reduce
the overbite while awaiting the eruption of
more teeth.
This is a problem only in severe Class II because milder
occlusal problems can be managed without help from growth.
In some circumstance it is important to know that growth is
complete. Surgical correction of jaw malrelationship is usually
delayed until after the pubertal growth.

89. In moderately severe Class III cases at the limits of
orthodontics it may be best to delay orthodontic intervention
in case unfavourable facial growth changes occur which
would take the malocclusion beyond the bounds of
orthodontic correction.

90. In a patient showing signs of having passed the peak of the
growth spurt (adult voice in boys / menarche in girls) and who
is gaining height at less than 7 cm per year it can be concluded
that growth is almost complete. This can also be confirmed from
hand wrist radiographs showing fusion of the radial and ulnar
epiphysis.

91. Facial growth continues at a very slow rate well into adult life
and may be responsible for minor changes in incisor
crowding.
However, this is not relevant to the timing of orthodontic
treatment or of orthognathic surgery. Anterior maxillary
traction can accelerate growth at the circum-maxillary sutures
and so increase displacement of the maxilla relative to the
cranial base.

92. Growth Considerations
The clinician should be aware of a few basic principles of
maxillary and mandibular growth.
The maxilla and the mandible grow in both a downward and
forward direction relative to the cranial base. At the peak of the
juvenile growth spurt (7 to 9 years of age), the maxilla grows 1
mm/yr and the mandible 3 mm/yr, whereas during the
prepubertal period (10 to 12 years of age) there will be a
reduced rate of growth (maxilla, 0.25 mm/yr; mandible, 1.5
mm/yr), only to reach maximum growth levels during puberty
(12 to 14 years of age) (maxilla, 1.5 mm/yr; mandible, 4.5
mm/yr).

93. The lower facial height (ANS-Me) increases approximately 1
In general, from 4 to 20 years of age, there will be on average 10
mm of pure alveolar growth. mm/yr, and the pogonion (Pg) comes
forward about 1 mm/yr.

94. Overall, mandibular growth is approximately twice that
of overall maxillary growth. The average direction of
maxillary sutural growth has been found to be 45 degrees
to 51 degrees in relation to the nasion-sella line from 8.5
to 14.5 years of age. Mechanisms responsible for the
maxillary growth displacement may be different in the
earlier and later periods of maxillary growth, as the
direction of sutural growth changes to almost horizontal at
the age of 14.5 years

95. This corresponds to the finding that the mean vertical maxillary
displacement has terminated by the age of 15 years, whereas
the horizontal displacement continues until 18 years of age in
boys and until 16 years of age in girls.
If the maxillary growth in boys is assumed to have terminated
by age 18 years and in girls by age 16 years, this corresponds
to an average annual lowering of 0.7 mm. Furthermore, increase
in facial height (vertical growth) continues at a much reduced
rate throughout early adulthood both in men and women.
The mean increase for total face height (nasion to menton)
during adulthood is almost 3 mm, but in individual cases it
may be in the order of 10 mm (1cm).

96. Growth Modification
Orthodontic problems in the preadolescents are generally
thought of as either dental or skeletal in origin. The complexity
of these problems varies tremendously. Many dental problems
are well within the treatment domain of the general practitioner.
Skeletal problems, as diagnosed from the facial profile analysis
and confirmed by supplemental means are best treated by
a specialist. However, the general practitioner should have an
understanding of how skeletal discrepancies are treated.

97. Three basic alternatives for treating skeletal discrepancies exist:
growth modification, camouflage, and orthognathic surgery.
Growth modification attempts to change skeletal relationships by using the
patient's remaining growth to alter the size or position of the jaws.
Camouflage and orthognathic surgery usually are considered only in the non
growing or adult patient.
The camouflage type of orthodontic treatment is aimed at hiding a mild
skeletal discrepancy by moving teeth situated on the jaws so that they fit
together. The skeletal discrepancy still exists but it is disguised by a normal
occlusion and acceptable facial esthetic appearance.
Orthognathic surgery places the jaws and teeth in a normal or near normal
position through the use of surgical procedures and pre-and postsurgical
orthodontic treatment.

98. three assumptions are made when growth modification is
undertaken.
First and most obvious, the patient must be growing the normal child in
this age group is actively growing; however, there is a wide variation in
the amount of growth occurring at one time and the coordination of
facial growth with overall body growth. Treatment is ideally planned to
coincide with the patient's maximum growth spurt so that the greatest
amount of modification can occur in the shortest amount of time.
Numerous investigators have tried to determine whether the peak
growth spurt can be predicted or anticipated by dental development,
skeletal development, or chronologic age. There is a weak relationship
between the peak growth spurt and each of these three indicators, but
these relationships may not be very useful clinically.

99. The clinician should use all three indices and a thorough
past medical history that includes a history of growth to
make an educated decision about whether the child is growing
at a fairly rapid rate.
Females tend to enter the adolescent growth spurt between the
ages of 9 and 11, and males are best treated between ages
11 and 13.
The discrepancy between dental development and maximum
growth velocity may create a situation in which the patient may
be ready for growth modification but not for orthodontic dental
treatment, and vice versa.

100. The second assumption made when growth modification
is undertaken is that the practitioner can accurately diagnose the
source of the skeletal discrepancy and then design treatment
that will apply the appropriate amount and direction offer to
correct the discrepancy. Diagnosis is not an exact science, and
the discrepancy may be due to a number of small skeletal
problems rather than to one easily identified discrepancy.
Force delivery to dental and skeletal structures is also inexact,
and the clinical impression and treatment response often dictate
the amount and direction offeree applied to modify growth.

101. The third assumption is that growth modification is usually only the
first phase of a two-phase treatment plan.
The appliances used to modify growth are basically designed to
alter skeletal structures rather than teeth. Although the
appliances are capable of causing tooth movement, they are not
as precise as fixed orthodontic appliances.
Therefore, most growth modification treatments are followed
immediately or at a later time by traditional fixed orthodontic
appliances to move the teeth into an ideal position

102. Three theories are offered to explain how growth modification
works to achieve the desire results. The first theory suggests that
growth modification appliances change the absolute size of one or
both jaws.
For example, a Class II skeletal profile may be treated by making a
deficient mandible larger to fit a normal sized maxilla or by limiting
the size of an oversized maxilla.

103. Some investigations on animals have shown that absolute
size change is possible, but clinical application in humans has
not been as successful. Certain individuals do show dramatic
size changes, but there appears to be large variability in
patient response to growth-modifying appliances,
with moderate changes being the rule rather than the
exception.

104. Growth modification may work by accelerating the desired
growth but not changing the ultimate size or shape of the jaw.
A deficient mandible may not end up larger than it ultimately would
have been, but it may achieve its final size sooner.
This allows the clinician to make some final dentoalveolar
changes to establish an ideal occlusion following growth modification
and to shorten total treatment time.
This type of growth modification response
also shows large individual variability.

105. A third possibility is that growth modification may work by
changing the spatial relationship of the two jaws. The ultimate
size of the jaw and its rate of growth are not changed, but by
modifying the orientation of the jaws to each other, a more
balanced profile may result. For example a convex profile and
an increased lower facial height could be made more proportional
to each other if the vertical growth of the maxilla could be
inhibited and the mandible allowed to rotate upward and forward.
The profile would then become less convex and the vertical
relations more ideal.

106. Jaw reorientation would be successful in a concave Class III
patient with a short face if the mandible could be rotated
downward and backward (more vertical) to create a more
acceptable profile. Reorientation does not work well in Class
II short faces or Class III long faces because correcting one
problem makes the other problem worse.

107. Growth modification applied to anteroposterior problems:
Antero-posterior skeletal problems are Class II and Class III in
nature. These descriptions are not very informative, however,
because the source of the discrepancy may be either the maxilla,
the mandible, or a combination of the two.
Therefore, the first step in patient evaluation is to identify the
source of the problem and then design a treatment plan to
resolve the problem.

108. Class II-Maxillary Protrusion:
Class II maxillary protrusion is best treated by Face-bow therapy to
restrict or redirect maxillary growth. Face- bow places a distal force
on the maxillary dentition and the maxilla. Theoretically, the relative
movement of dental and skeletal structures depends on the amount
and time of force application.
In actual practice, it is probably not possible to move selectively only
teeth or bones. However, more tooth movement occurs if the face-
bow is worn more than 16 hours per day at force levels of 12
ounces or less.

109. Conversely, more orthopedic or skeletal effect is expected if the
face- bow is worn between 8 and 12 hours per day at force levels of
16 ounces or more. The vertical direction of force exerted by the
face-bow varies according to the type of face-bow chosen.
One should avoid using a face-bow that tends to extrude posterior
teeth in a long face individual. However, the same type of face bow
would be useful in a patient with a deep bite and a short face.

110. Class II maxillary protrusion may also be treated with a functional
appliance (for example an activator). Although a functional
appliance is primarily designed to stimulate mandibular growth,
studies have indicated that it has a secondary effect of restricting
maxillary skeletal and dental movement. This happens because the
mandible, which is postured forward, returns to a more distal
position due to the distal muscle and soft tissue forces transmitted
through the appliance to the maxilla and the maxillary teeth. The
maxillary teeth tend to tip lingually rather than to move bodily, and
the mandibular teeth tip facially.

111. Class II Mandibular Deficiency :
The mandibular deficient patient is usually treated with a functional
appliance (for example an activator) that positions the mandible
forward in an attempt to stimulate or acelerate mandibular growth.
Twin block
activator

112. Retrospective clinical studies have shown that these appliances
can produce a small average increase in mandibular projection
(2-4 mm/ year).
There is a great amount of variability in patient response. In
most cases, this increased growth will not totally correct the
Class II skeletal problem for several reasons.
First; the amount of growth is not enough to overcome the
discrepancy.
Second, all the available growth would need to be used to produce
antero-posterior change.

113. This is usually not the case because some eruption and vertical
growth occurs.
This interaction between antero-posterior and vertical dimension
changes decreases mandibular projection and Class II correction
because the mandible grows downward and forward and not straight
forward. The rest of the antero-posterior discrepancy is made up by
restricting maxillary growth, tipping the maxillary teeth back, and tipping
the mandibular teeth forward.

114. Different appliances can be prescribed that will exaggerate
the secondary responses of maxillary restriction and dental
movement if desired. There are some studies that indicate
that face-bow treatment may cause a small increase in
mandibular growth, but it is unlikely that the amount of
mandibular stimulation by this method would be of clinical
significance.

115. Class III Maxillary Deficiency:
True midface deficiency can be treated by using a reverses-pull
headgear or face mask to exert anteriorly directed force on the
maxilla. The ideal time to attempt this treatment is between the ages
of 6 and 8 if skeletal change is desired. Because the face mask
applies force to the maxilla through an appliance (either a
removable splint or fixed appliance) attached to the teeth, tooth
movement also occurs.

116. In fact, after age 8 this type of appliance has a tendency to
exert a predominantly tooth-moving force.
Functional appliances designed to stimulate maxillary growth
do not seem to be effective. The improvement in facial profile
obtained by using these appliances in patients with very minor
Class III problems is the result of a downward and backward
rotation of the mandible. The occlusion improves as a result of
facial tipping of the maxillary incisors and lingual tipping of the
lower incisors.

117. Class III mandibular protrusion has been historically treated by chin
cup therapy.
The strategy of chin cup therapy is to apply a distal and superior
force through the chin that will inhibit or redirect growth at the
condyle. Again, studies in animals have shown some change in
absolute mandibular size, but clinical application in humans routinely
has been less successful. The typical response to chin cup therapy is
a distal rotation of the mandible and lingual tipping of the lower
incisors.

118. Therefore, chin cup therapy is well tolerated in patients with mild
mandibular protrusion and short to normal vertical proportions. It
is contraindicated, however, in an, individual with a long lower face
because the anteroposterior correction would come at the
expense of an increased vertical dimension. Functional appliances
designed to treat Class III mandibular excess show the same
changes as those seen in Class III maxillary deficiency.

119. Growth Modification Applied to Transverse Problems:
The most common transverse problem in the preadolescent is
maxillary constriction and posterior crossbite.
Treatment of maxillary constriction should begin as soon as the
problem is discovered if the child is mature enough to accept
treatment.
Three basic appliances are used to correct the constriction, but the
appliances are not interchangeable. Quad helix and the W arch are
fixed appliances that used for treatment of maxillary constriction.

120. These appliances provide both skeletal and dental movement
in the 3-to 6-year-old child. As the patient grows older, more
dental change and less skeletal change occur.
This is true because the midplalatal suture, which was open at
an early age ,has developed bone Interdigitation that makes it
difficult to separate. More force is required to separate the
suture and obtain true skeletal correction than a quad helix or W
arch can deliver.
A, Bilateral constricted maxilla with upper midline shift; B,
type 2 RME appliance in mouth; C, end of expansion; D,

121. In the older preadolescent patient, in whom there is a chance
that the midpalatal suture is closed, an appliance that can deliver
large amounts of force is necessary to correct the skeletal
constriction. Rapid palatal expansion is the term given to the
procedure in which an appliance cemented to the teeth is opened
0.5 mm/day to deliver 2000 to 3000 gm of force.
In the active phase of treatment, there is little dental movement
because the periodontal ligament has been hyalinized, which limits
dental movement, and the force is transmitted almost entirely to
the skeletal structures. During retention, however, the skeletal
structures begin to relapse toward the midline.

122. Because the teeth are held rigidly by the appliance, there is some
compensatory dental movement to maintain the same width.
Depending on the amount of expansion needed, active treatment
normally takes 10 to 14 days. Another approach to skeletal
expansion is slow rather than rapid palatal expansion. Essentially the
same appliance is used, although force levels are calibrated to
provide only 900 to 1300 gm of force.
Coupled with a slower activation rate, slow palatal expansion
widens the palate by dental and skeletal movement. Although the
final position of the teeth and supporting structures is approximately
the same in rapid and slow expansion, proponents of slow expansion
maintain that slower expansion is more physiologic and stable.

123. Transverse growth modification also can be accomplished by
means of acrylic or wire buccal shields attached to functional
appliances.
The buccal shields relieve the teeth and alveolar structures
from the resting pressure of the cheek muscles and soft tissues.
Transverse expansion of 3 to 5 mm can be achieved, although
the changes are quite variable. Whether the movement is dental
or skeletal and whether it will remain stable remains in question
because there are no controlled experimental studies to provide
answers.

124. Growth Modification Applied to Vertical problems :
Vertical skeletal problems become manifest as long and short
facial heights and usually are located below the palatal plane. The
short face individual has a reduced mandibular plane angle and
under erupted teeth. In the long face patient, the mandibular plane
angle, lower facial height and amount of dental eruption are
increased compared with the patient with a normal face.
Vertical skeletal problems certainly may be treated successfully
with growth modification techniques; however, maintaining the
correction is extremely difficult. The face grows vertically for a long
time, and there is a tendency for the original growth pattern and
growth problem to recur.
Long faceShort face

125. Vertical Excess:
Vertical skeletal excess may be treated by extraoral force,
intraoral force, or a combination of the two.
Extraoral force is delivered by means of a high-pull face-bow
through the maxillary first molars. The force is applied in a
superior and distal direction and is designed to inhibit vertical
development of the maxilla and eruption of the posterior
maxillary teeth.
Because no force is applied to the mandibular teeth, they are
free to erupt and compensate for the lack of vertical development
in the maxilla.
This compensatory eruption can eliminate
all the positive effects of the high-pull
face-bow and lead to downward and
backward rotation of the mandible instead
of forward projection.

126. An alternative method for controlling vertical development is
to block the eruption of the maxillary and mandibular teeth.
A functional appliance can be designed that will force the
mandible open to an increased vertical position.
The force of the mandible attempting to return to its original
vertical position is transmitted to the maxilla and the teeth in
both arches. This results in mandibular growth being directed
forward because no dental eruption has occurred to increase
the vertical dimension.
Posterior bite plates

127. To supplement the effect on the maxilla, a face bow can be
attached to the functional appliance that will allow the face bow
and functional appliance to be worn at the same time.
Developments in rare earth magnetics may also prove to be of
value in restricting vertical facial development.
Magnets placed to repel each other in each arch may provide
enough force to restrict vertical eruption and skeletal growth.
By whatever means vertical excess is treated, excellent patient
cooperation is necessary because treatment must be continued
as long as the patient is growing.
Van beek appliance Lehman appliance
magnets

128. Vertical Deficiency:
Vertical skeletal deficiencies can be treated with either face bow or
functional appliances depending on the accompanying antero-posterior
relationships.
The force vector from the face bow should direct the maxilla
distally and extrude the maxillary posterior teeth. Because functional
appliances are typically designed to inhibit eruption of upper and lower
anterior teeth and promote eruption of the posterior teeth, they can
also increase vertical facial height. As in vertical skeletal excess, the
original growth pattern tends to recur, and retention should be
designed to prevent this recurrence.
Anterior bite plateLow pull head gear

129. Reference
Orthodontics for dental students. Third edition
published 1976 by the MACMILLAN PRESS
LTD London and Basingstoke