1.
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
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2.
Contents• Introduction
• Modes of Expansion
– Orthodontic expansion
– Passive expansion
– Orthopedic expansion
• Orthopedic expansion
– W –Arch, Quad helix
– Schwarz appliance
• Rapid Maxillary Expansion
– Biological basis of Rapid Maxillary Expansion
– Uses and contraindications of maxillary expansion
– Biomechanics of Rapid Maxillary Expansion
– Effects of Rapid Maxillary Expansion
– Treatment timings
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3.
• Appliance design
– Banded appliance
• Haas appliance
• Hyrax appliance
• Minni expander
– Bonded appliance
– Butterfly expander
– Fan shaped expander
– Nickel palatal expander
• Slow Maxillary Expansion
• Semi Rapid Maxillary Expansion
• Effects of Rapid Maxillary Expansion in skeletally mature
patients
• Surgically assisted rapid palatal expansion (SARPE).
• Bone borne palatal expander
• Conclusion
• References
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4.
Introduction
• Expansion of the maxillary arch to correct
transverse skeletal and dental discrepancies
and to reduce intra-arch crowding is an
accepted method of treatment that was first
outlined by Angel in 1860 and popularized by
Haas 100 years later.
• During this time various appliances were
developed to create maxillary expansion ranging
from the basic removable acrylic appliances with
a midline screw to the banded or bonded
expansion devices.www.indiandentalacademy.com

5.
• The concept of rapid palatal expansion to
attain skeletal widening of the maxilla was
revisited by Goddard in the 1890s and by
Landsberger in 1910, but the technique
seemed to languish for the next 50 years
until numerous studies confirmed the
creation of skeletal rather than dental
changes.
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6.
Modes of Expansion
• Expansion of the dental arches can take
place by
– Orthodontic expansion
– Passive expansion
– Orthopedic expansion
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7.
Orthodontic Expansion
• Orthodontic expansion is produced by
conventional fixed appliances and by
various removable expansion plate and
finger spring appliances
• It usually result in lateral movements of the
buccal segments that primarily are
dentoalveolar.
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8.
• A tendency exists toward a lateral tipping
of the crowns of the involved teeth and a
resultant lingual tipping of the roots.
• The resistance of the cheek musculature
and other soft tissue still
remains, providing forces that may lead to
a relapse or rebound of the achieved
orthodontic expansion.
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9.
Passive expansion
• When the forces of the buccal and labial
musculature are shielded from the
occlusion, as with the Frankel appliance, a
widening of the dental arches often
occurs.
• Brieden et al, in an implant study
conducted in patients treated with the FR-
2 appliance of Frankel, have demonstrated
that bone deposition occurs primarily
along the lateral aspect of the alveolus
rather than at the mid palatal suture.www.indiandentalacademy.com

10.
• During deglutition Anterior lip seal and
Posterior oral seal creates a Negative
atmospheric pressure within oral cavity
• So the Cheeks are sucked into
interocclusal space as mandible returns
into postural rest position
• This exerts an Constricting influence on
the dentoalveolar process and
prevention of eruption of buccal segments
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11.
• Thus Shields prevent the pressure of the
buccinator on the dentoalveolar area
during deglutition and at rest, inducing
downward and outward movement of teeth
and tissues.
• A related type of spontaneous arch
expansion also has been observed
following lipbumper therapy.
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12.
Periosteal pull of Buccal shields:
Shields and pads can be extended into the depth of vestibule
Causing tension without creating irritation
This produces a pull on the contiguous periosteal tissue of
the maxillary bone
leading to increased bone activity in contiguous osseous
structure
Maxillary basal bone is widened
Alveolar shell over the erupting teeth proliferates laterally
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13.
• In a study conducted at Manipal &
Davangere by P.P. Biswas , K.S.
Shetty, A.Valiathan (JIOS 1993), 10 cases
treated by the Frankel appliance were
examined for changes in arch width post
treatment.
• All teeth except maxillary canine exhibited
buccal bodily movement due to periosteal
pull provoked by the vestibular shields.
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14.
The Lip Bumper
•The lip bumper is useful
particularly in patients who
have tight or tense buccal
and labial musculature.
• It is made of heavy wire to
prevent distortion.
•The wire is adjusted to be
1.5 to 2mm facial to the lower
incisors and the plastic shield
is added to increase contact
with the lip.

15.
• The appliance usually is worn full time
and may be ligated in place.
• The lip bumper also would lie at the
gingival margin of the lower central
Incisors.
• So it not only increases arch length
through passive lateral and anterior
expansion but also serves to upright the
lower molars distally, adding to the
available arch length increase.
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16.
Orthopedic Expansion
• Three methods to cause maxillary expansion are
– Split removable plate with jack screw
– Lingual arch- a W- Arch or quad helix
– Fixed palatal expander with a midline screw
• In primary dentition and early mixed dentition
less force is required to open the suture, so all
three methods produce both dental and skeletal
effects
• Even in late mixed dentition, sutural expansion
requires placing a relatively heavy force across
the suture
• This can be achieved by both slow and rapid
maxillary expanders in late mixed dentitionwww.indiandentalacademy.com

17.
• Split palate with jack screw
– Although it is possible to expand maxilla in
mixed dentition with a split palate type of
removable appliance, there are two problems
• This depends upon patient compliance for success
• Appliance can be easily displaced
– So this approach is less successful and less
cost-effective than expansion lingual arch
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18.
The W-Arch
• The W-Arch was originally used by Ricketts to
treat cleft palate conditions
• This is a fixed appliance constructed of 36 mil
steel wire soldered to molar bands
• This appliance is activated by opening the
apices of W
• The appliance delivers proper force levels when
opened 4-5 mm wider than the passive width
• It common for teeth and maxilla to move more
on one side than the other, so precise bilateral
expansion is the exception rather than the rule
• But still acceptable correction and tooth position
are almost always achieved
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19.
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20.
The Quad helix
• This is the more flexible version of W-Arch
• In order to increase the range of force and
produce more flexibility, total of four helical
loops were incorporated in anterior and
posterior segments creating a quad helix
appliance
• It is made of 0.038 inch round stainless
steel or blue eligioy wire and soldered to
bands that are cemented either to the
permanent maxillary 1st molar or
deciduous 2nd molars.
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21.
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22.
Activation of Quad Helix
• As a rough guide, it is expanded extraorally such
that the bands of the quad helix lie half way past
the molar crowns, before cementation.
• Intraorally it is activated with a 3 prong plier at
the anterior and posterior palatal bridges every
other week.
• Intraoral appliance adjustment may lead to
unexpected changes, and so removal and
recementation are recommended at each
activation visit
• The forces produced by the quad helix are in the
range of 0.5 to 1.5 lbs( 200- 600g). These forces
are well below those exerted by the Jackscrew
expander. www.indiandentalacademy.com

23.
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24.
Modifications of Quad helix
1. It can be used in conjunction with a
protraction facemask to advance the maxilla.
2. The anterior bar of the quad helix appliance
may be modified to counter thumb sucking
and tongue thrust habit or to control eruption
of anteriors.
3. It may be also used to maintain space and
to augment anchorage when required.
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25.
Schwarz appliance
• This is a removable expansion plate that can be
used in early stages of mixed dentition in the
mandible
• This appliance was mentioned over a hundred
years ago by Kingsley
• The appliance consists of simple ball clasp placed
between the first and second deciduous molars
and the permanent first molar
• If additional retention is needed Adams clasp can
be placed in permanent first molar
• The expansion screw is placed in midline and
almost entirely embedded In acrylicwww.indiandentalacademy.com

26.
• The Schwarz appliance can be used in patients
who have arch length deficiencies and/or posterior
teeth that have an abnormal lingual inclination
• It is rare that we could use Schwarz appliance as
a sole appliance to produce orthodontic tooth
movement, an exception is the treatment of patient
with posterior buccal crossbite(scissors bite)
• The gradual expansion of Schwarz appliance
produced by activation of midline screw, simply
tips the posterior teeth in a lateral direction
• This is followed by Rapid Maxillary Expansion
which would stabilize mandibular dentoalveolar
position during the retention period
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27.
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28.
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29.
Rapid maxillary expansion
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30.
Rapid Maxillary Expansion
• Rapid maxillary expansion (RME) constitutes a
routine clinical procedure in orthodontics, with its
main purpose to normalize the constricted
maxillary arch.
• Forces of large magnitude delivered during
activation of an expansion screw open the
intermaxillary suture, increasing the basal bone
width and the dental arch perimeter.
• In addition to the desirable transverse
altérations, RME produces perceptible changes
in the sagittal and vertical facial planes.www.indiandentalacademy.com

31.
Biologic basis of Rapid Maxillary
Expansion
• Upon the application of transverse
biomechanical forces, initial changes involve the
lateral tipping of the posterior maxillary teeth as
the periodontal and palatal soft tissues are
compressed and stretched.
• This stage of orthodontic response appears to
be essentially complete within a week.
• Subsequent orthodontic movements will occur
through bodily translation as the compressed
buccal alveolar plate resorbs at the root-
periodontal interface from continued force
application. www.indiandentalacademy.com

32.
• The theory was that with rapid force application to
posterior teeth, there would be not enough time for
tooth movement, the force would be transferred to
the suture
• If the applied transverse forces are of sufficient
magnitude to overcome the bioelastic strength of
sutural elements, orthopedic separation of the
maxillary segments can occur.
• The separation and repositioning of the palatal
segments will continue until the force distribution is
reduced below the tensile strength of the sutural
elements.
• Reorganization and remodeling of the sutural
connective and skeletal tissues may then proceed
in the stabilization of the expanded maxillary arch.
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33.
Uses of Maxillary expansion
• Correction of crossbites
– Most commonly recognized indication for maxillary
expansion
– It is very common for one or more of maxillary teeth to be
in lingual orientation relative to mandibular dentition
– Through widening of midpalatal suture the correction of
posterior crossbite is accomplished
• Addition of arch length
– Expansion results in increase in total arch length which
will allow accommodation of rotated, displaced or
impacted teeth
– Adkins and Nanda AJO 1990 reported that Rapid
maxillary expansion yielded 0.7 mm increase in arch
perimeter for every 1 mm increase in first premolar width
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34.
• Correction of axial inclination
– Patients with maxillary constriction and subsequent
dento-alveolar compensation show a buccally flared
orientation of posterior teeth
– Severe cases in which buccal root torque to correct
its inclination might cause cortical plate
perforation, can be corrected using maxillary
expansion followed by fixed appliance to just tip the
teeth rather than application of buccal root torque
• Spontaneous correction of class II
– Widening of maxilla in class II cases with maxillary
constriction in mixed dentition often leads to
spontaneous posturing forward of mandible during
retention period
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35.
• Preparation for functional jaw orthopedics
– Many cases being prepared for functional
appliance require an initial phase of rapid
maxillary expansion, to widen the maxilla and
to correct tooth size and arch length
discrepancies
• Orthopedic correction of early class III
– Even in patients whom maxillary expansion is
not indicated, rapid maxillary expansion can
be done to disrupt the circumaxillary sutural
system to facilitate response of maxilla
– The bonded rapid maxillary expansion is also
used to anchor the orthopedic face mask to
maxillary dentition
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36.
• Reduction in nasal resistance
– Although not a predictable part, significant number of
patients demonstrate reduction in nasal resistance
following rapid maxillary expansion
• Broadening the smile
– Although there is little clinical research to support
rapid maxillary expansion for esthetic purposes, it is
expected to become increasingly common for patients
with large buccal corridor spaces
• Reduction in night time bed wetting or nocturnal
enuresis
• Improvement in hearing level of subjects with
conductive hearing loss
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37.
Contraindications for RME
• Uncooperative patients
• Single tooth crossbites
• Patients who have anterior pen bites and
steep mandibular plane angles and
convex profiles
• Skeletal asymmetry of maxilla or mandible
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38.
Biomechanics of Rapid
Maxillary Expansion
Lee et al AJODO 1997 identified centre of
resistance of dentomaxillary complex
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39.
Stanley Braun AJODO 2000
Frontal view
Occlusal view
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40.
Frontal view
Occlusal view
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41.
• If less tipping were desired (in the frontal view) and
a more linear opening of the maxillary suture
anteroposteriorly (in the occlusal view), the
fabricated structure joining the sutural opening
mechanism to the teeth would have to be more
rigid,
• By increasing the rigidity of both the sutural
expansion device and the wires joining it to the
teeth, the moment induced by the necessary offsets
from the dentomaxillary centers of resistance are
reduced, resulting in reduced equivalent moment-
to-force ratios at the centers of resistance.
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42.
• This causes the center of rotation to migrate
superiorly in the frontal view, reducing the
degree of tipping, and in the occlusal view, the
center of rotation would migrate further
posteriorly, resulting in a more linear separation
of the midpalatal suture.
• Increased rigidity can be obtained by using the
largest possible diameter stainless steel wires
and a larger diameter activating screw.
• The sutural expansion designs that use an
acrylic interface with the teeth are far less stiff
than those constructed solely of soldered
stainless steel wire.
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43.
Effects of Rapid Maxillary
Expansion
• In a finite element study conducted to evaluate
stress distribution along craniofacial sutures and
displacement of various craniofacial structures
with rapid maxillary expansion (RME)
therapy, Pawan Gautam and Ashima Valiathan
AJODO 2007 reported that the wedge-shaped
opening was produced both anteroposteriorly
and superoinferiorly
• Separations were pyramidal, with the base of the
pyramid located at the oral side in the vertical
plane and anteriorly along the anteroposterior
plane. www.indiandentalacademy.com

44.
• The reason for the wedge-shaped opening in the
anteroposterior plane is the pterygomaxillary
connection that binds the sphenoid bone to the
maxillary bones.
• The entire maxilla moved anteriorly and
downwards in response to RME
• This is probably due to the disposition of the
maxillocranial sutures.
• Sicher claimed that these sutures are oriented
so that growth would produce a downward and
forward force vector of maxillary movement.
• The maxilla rotated in a clockwise direction with
ANS showing more downward displacement
than PNS. www.indiandentalacademy.com

45.
• Garib et al AO 2007 evaluated the long-term
effects of rapid maxillary expansion (RME) via
banded expanders in the sagittal and vertical facial
planes.
• The findings of this study revealed that the
maxillary sagittal position remained unchanged in
relation to the cranial base, considering the slight
changes in SNA angle in the RME group, also
ANB and bony profile convexity (NAP) were
reduced in both the groups
• There were no statistically significant differences
between the study groups in changes observed for
upper anterior and posterior facial heights (UAFH
and UPFH) www.indiandentalacademy.com

46.
• Thus, the alterations that occur immediately after
expansion and are frequently reported in the
literature, such as increases in facial convexity
and overjet, should be considered ephemeral
phenomena.
• These results do not provide a basis to
contraindicate RME in patients with a convex
profile based on the side effects observed soon
after expansion.
• Also even though RME causes vertical maxillary
displacement, as demonstrated by several
studies, this vertical alteration is not significant in
the long term
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47.
Pterygoid plates
• Both the lateral and the medial pterygoid plates
were displaced laterally
• The inferior portions of the medial and lateral
pterygoid plates were displaced more compared
with the superior portions.
• This can be explained by the fact that the
pterygoid plates are more resistant to bending in
the parts closer to the cranial base where the
plates are much more rigid.
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48.
• The main resistance to the midpalatal suture
opening is probably not in the suture itself;
rather, it is in the surrounding structures with
which the maxilla articulates, particularly the
sphenoid and the zygomatic bones
• The pterygoid plates of the sphenoid are
connected to the horizontal plate of the palatine
bones through the pyramidal process of the
palatine bones.
• The pterygoid plates can bend only to a limited
extent with pressure, and this confining effect of
the pterygoid plates of the sphenoid minimizes
dramatically the ability of the palatine bones to
separate at the midsagittal plane.www.indiandentalacademy.com

49.
Zygomatic bone
• The zygomatic bone was displaced laterally and
posterosuperiorly, with the body and the temporal
process of the zygomatic bone showing maximum
overall displacements
• The lateral structures of the maxilla (tuberosity and
zygomatic buttress) were displaced
posterosuperiorly.
• The probable explanation for the posterosuperior
displacement of the lateral maxillary structures
compared with median structures that were
displaced anteroinferiorly is the rotation of the 2
halves of the maxilla, with different centers of
rotation in all 3 planes of space.
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50.
• The lateral nasal cavity wall was displaced
laterally, indicating an increase in nasal cavity
width.
• This, along with lowering of the palatal plane, will
reduce nasal airway resistance
• The increase in nasal cavity width was more
pronounced in the inferior portion than in the
superior portion, widen as much as 8 to 10 mm at
the level of the inferior turbinates.
• The nasal bone and nasal process of maxilla
moved medially after RME, which might lead to
compression in the nasal region.
• This explains the frequent pain and pressure in the
nasal region experienced during palatal expansion
therapy
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51.
Stress pattern along sutures
• The maximum von Mises stresses were
experienced by the medial aspect of the
frontomaxillary suture, the superior
portion of the nasomaxillary suture, the
lateral aspect of the frontonasal
suture, and the lateral surface of the
sphenozygomatic suture
• Loading of the zygomatic arch is more
complex and is likely to include bending
in several planes, with shearing and
twisting www.indiandentalacademy.com

52.
• Along the superior portions of the zygomatic
arch at the zygomaticotemporal suture, the
medial margins were associated with
compressive stresses, whereas the lateral
margins were associated with tensile stresses
• The stress pattern was reversed along the
inferior portions of the zygomatic arch, with the
lateral and medial margins of the
zygomaticotemporal suture showing
compressive and tensile stresses, respectively.
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53.
Effects of RME on the roots and
periodontium:
• Isaacson and Ingram 1964, rapid expansion
appliances are capable of generating up to 10kgs
of force per activation on supporting teeth. Such
high forces could cause resorption of roots of
anchor teeth.
• Barber and Sims (AJO1981) studied the effects of
RME on the external root structure using scanning
electron microscopy.
• All anchor premolars exhibited root
resorption, which was confined mainly to the
buccal surface.
• The fact that this resorption is sustained long after
termination of active RME suggests the role of
residual loads in the appliance.www.indiandentalacademy.com

54.
• Garib et al AJODO 2006 studied periodontal
changes by means of computed tomography after
RME with tooth-tissue-borne and tooth-borne
expanders.
• RME reduced the buccal bone plate thickness of
supporting teeth 0.6 to 0.9 mm
• RME induced bone dehiscences on the anchorage
teeth’s buccal aspect (7.1 4.6 mm at the first
premolars and 3.8 4.4 mm at the mesiobuccal area
of the first molars), especially in subjects with
thinner buccal bone plates.
• The tooth-borne expander produced greater
reduction of first premolar buccal alveolar bone
crest level than did the tooth-tissue-borne expanderwww.indiandentalacademy.com

55.
Changes in mandible following
Rapid maxillary expansion
• Haas in 1961 using his midpalatal suture-opening
appliance without any treatment in the lower
arch, and observed that the mandibular arch
tended to follow the maxillary teeth by tipping
laterally.
• In a later study,(1980) he reported that Some
cases achieved and maintained an expansion of 3
to 4 mm in the lower intercanine width, and up to
6 mm in the intermolar width.
• He claimed that mandibular intercanine width can
be increased in the nongrower if the apical basewww.indiandentalacademy.com

56.
• Lima et al AJODO 2004 investigated the
spontaneous mandibular arch response to rapid
palatal expansion as the sole orthodontic
intervention and its stability long term post
treatment ( mean 11.3 years)
• Changes after maxillary expansion showed a
significant increase of 1.47 mm in mandibular
intermolar width (occlusal) and 0.97mm for
lingual value.
• The increase in intercanine width (lingual) of
0.26 mm. There were no statistically significant
changes for occlusal intercanine width.
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57.
• The overall changes from pre-expansion
to long-term follow-up were a significant
mandibular intermolar width increase of
0.93 mm (lingual) and 0.72 mm (occlusal)
• The intercanine width (lingual) decreased
significantly, 0.99 mm. There were no
statistically significant changes for
mandibular intercanine width (occlusal)
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58.
Maturational changes in
midpalatal suture
• Scott (1956) considered that growth in suture
ceases at the age of 1 year
• Bjork (1964) pointed out that growth in
midpalatal suture continues for a considerable
longer period than formerly believed
• Brite Melson AJO 1975 studying palatal growth
with histological and microradiogaphic
investigation on human autopsy material
showed that transverse growth of midpalatal
suture continued up to the age of 16 in girls and
18 in boys www.indiandentalacademy.com

59.
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60.
Treatment timing
• Wertz and Dreskin (1977) noted greater and
more stable orthopedic changes in patients
under the age of 12 years
• Bacetti ( AO 2001) showed that RME is able to
induce significantly more favorable skeletal
changes in transverse plane when it is initiated
before the pubertal peak in skeletal growth
• Clinicians have commonly reported difficulty in
producing palatal separation following the
pubertal growth period, while favorable
orthopedic responses have been indicated prior
to and during pubertal growth.www.indiandentalacademy.com

61.
• A direct relationship between increased resistance
to skeletal expansion and increasing patient age
has been quantified and associated with the
formation of mechanical interlockings at maxillary
articulations as early as 12 to 13 years of age.
• In addition the enhanced skeletal response in
younger age groups has been associated with a
greater cellular activity in the growing suture.
• Ten Cate and associates reported that the sutural
tissues in young growing rats were characterized
by increased fibroblastic, fibroclastic, and
osteoblastic activity following rapid expansion in
contrast to a less marked activity in more mature
animals. www.indiandentalacademy.com

62.
Effect of rapid expansion done in
children
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63.
Appliance design
• Banded rapid maxillary expansion
appliances
– Haas type appliance
– Hyrax type appliance
– Minne expanders
• Bonded rapid maxillary expanders
• Butterfly type expanders
• Fan shaped expanders
• Nickel palatal expanderswww.indiandentalacademy.com

64.
The Haas type expander
• The first type of expansion appliance was
popularized by Andrew Haas in 1961
• This appliance consisted of bands placed on
maxillary first premolar and the first molar
• A midline jackscrew is incorporated into two
acrylic pads that closely contact the palatal
mucosa
• Support wires are extended anteriorly from
molars along the buccal and lingual surfaces of
posterior teeth to add rigidity to the appliance
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65.
The Haas type expander

66.
• Haas states that more bodily movement
and less dental tipping is produced when
an acrylic palatal coverage is added, thus
permitting forces to be generated not only
against the teeth but also against
underlying soft and hard palatal tissues
• But the side effect includes inflammation
of the palatal mucosa
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67.
Hyrax type expander
• It is more commonly used type of banded RME
appliances, the design of which has been credited
to Biedermann.
• This type of expander is made entirely of stainless
steel, and does not include palatal acrylic, hence
considered more hygienic by many practitioners
• Bands are placed on maxillary first molars and first
premolars
• The appliance screw is placed in the palate in
close proximity to palatal contour
• Buccal and lingual support wires are added for
rigidity www.indiandentalacademy.com

68.
Hyrax type expander

69.
• One of the concerns of Hyrax appliance is that it
may be more flexible than the Haas appliance
producing more dental tipping and less sutural
expansion
• Ralph (1998) used a finite element analysis to
compare the difference between Hyrax and Haas
appliance in affecting midpalatal suture, teeth and
attached stuructures
• He reported that average tipping effects are 2.5-3
times greater in Hyrax model compared to Haas
model, while the later showed more tooth and
sutural displacement
• The Hyrax model also showed more deformation
and thus decreased energy available on activationwww.indiandentalacademy.com

70.
• Oliveria et al AJODO 2004 used a three
dimensional assessment to compare the effects
of Haas and Hyrax appliances. They reported
that Haas appliance showed a greater
component of true orthopedic movement while
Hyrax caused dentoalveolar expansion
• The orthopedic movement caused by Haas
appliance was signified by greater gain in
interpalatal width while dentoalveolar expansion
caused by Hyrax appliance was revealed by
greater interpalatal angulation after treatmentwww.indiandentalacademy.com

71.
The Bonded acrylic splint
expander
• Bonded appliances were designed to cover the
maxillary posterior occlusal-buccal segments so
that the appliance not only serves as an expansion
device but intrudes on the freeway space through
its vertical thickness
• It acts as a functional appliance with a small range
of clinical application
• 2-3 mm of acrylic is bonded to maxillary posterior
teeth so that passive stretch of elevator and
retractor musculature provides an apically directed
force to maxilla and mandible ( Ahlgren 1970 and
Graber 1977)
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72.
• The bonded Rapid maxillary expander would
increase rigidity by limiting unwanted tipping and
rotation of teeth due to increased surface of
acrylic bonded to teeth
• Further more tooth supra eruption would be
limited because of bonding the entire posterior
arch
• Memikoglu and Iseri 1997 investigated the
effects of Haas type RME and rigid acrylic
bonded RME appliances
• They reported an increase in tipping of upper
molars and decrease in overbite in Haas group
compared with Bonded groupwww.indiandentalacademy.com

73.
• Sarver and Johnston AJODO 1989 examined the
effect of acrylic spint expander in 20 patients who
were on average 11 years of age at the beginning
of treatment. Compared to the findings from a
study by Wertz using Haas appliance, the bonded
appliance showed a decrease in inferior
displacement of maxilla
• Steven Asanza et al 1997 investigated the effects
of Hyrax type RME and Bonded expansion
appliance and reported that increase in the
vertical dimension often seen with more
conventional Hyrax may be minimized or negated
with bonded appliance
www.indiandentalacademy.com

74.
Combined Bonded RME and Vertical chin
cap
• Nisco and Nanda (1986) and Majourau and
Nanda (1994) investigated the use of RME
together with a high pull headgear and high pull
chin cap.
• They recommended the use of high pull chin cap
to provide a more ideal force system
• Basciftci and Karaman 2002 concluded that the
vertical chin cap is an effective appliance for
preventing the adverse vertical effect of RME in
patient with a crossbite and vertical growth
pattern
www.indiandentalacademy.com

75.
The Butterfly Expander for
use in the mixed dentition:
Cozza, Giancotti, Petrosino
( JCO 1999)
It is a rapid palatal
expansion appliance which
follows the basic design of
Hass, with a few
modifications.
It comprises a high
midpalatal
jackscrew(A0620), attached
to a butterfly shaped stainless
steel framework that extends
forward to the palatal surfaces
of deciduous canines.www.indiandentalacademy.com

76.
The appliance is soldered to
bands on the 2nd deciduous
molars. The rigidity of the
appliance and its location high in
the palatal vault allows
transverse force to be delivered
closer to the center of resistance
of the posterior teeth than with
conventional expanders. The
butterfly design thus minimizes
posterior tipping and extrusion.
As it is applied to the primary
molars, it will not cause root
resorption of anchored molars
and premolars.
It is recommended for use in
the early mixed dentition.www.indiandentalacademy.com

77.
Fan shaped expander
Levrini, Filippi (JCO Nov 1999)
• Patients with narrow maxillae sometimes require
differential expansion of the anterior and posterior
segments, as in cleft lip and palate cases.
• To that end, Schellino and Modica have designed a
―spider screw‖ that works asymmetrically and allows
fan opening.
• Mechanism: The expander is made of stainless
steel, with the spider screw as the active component.
• There are three pivot points: a posterior one, which
allows the ―fan‖ opening, and two anterior
ones, which counteract the torquing forces produced
during expansion.
www.indiandentalacademy.com

78.
Four arms, two mesial and
two distal, are welded to the
expander and to bands on
the teeth.
The type of expansion
produced depends on the
angulation and length of the
arms.

79.
www.indiandentalacademy.com

80.
Nickel palatal Expander
• It was developed by Dr Wendell Arndt (Kansas) in
1993, in order to overcome the limitations of
conventional expansion appliances, in JCO, March
1993 issue as ― A tandem loop nickel titanium
temperature activated palatal expander with the
ability to produce light continuous pressure on the
mid-palatal suture while simultaneously up
righting, rotating an distalizing the maxillary 1st
molars‖
• The Ni-Ti expander has a transition temperature of
94degress centigrade below which the interatomic
forces weaken, making the metal much more
flexible. When it is chilled before insertion in the
patients mouth it can be easily bent to facilitate
www.indiandentalacademy.com

81.
• They come in 8 different intermolar widths from
26- 47 mm, The appropriate size is determined
by measuring the amount of expansion
needed, then adding 3mm for overcorrection.
• When the appliance begins to stiffen in the
patients mouth, it may initially cause some
discomfort.
• This can be alleviated by sipping a cold liquid
which will temporarily make the NiTi more
flexible.
• If more than 8mm expansion is needed then two
expanders must be used in succession.
www.indiandentalacademy.com

82.
Recommended treatment time are as follows:
Expansion Retention
Primary dentition 1-2mths 2mths
Mixed Dentition 2-3mths 2mths
Young Adults 3mths 2mths
Adults 5 or more 3mths
Advantages:
1 Self activated by body temperature.
2Automatically expands to its predetermined shape.
3.Require little manipulation by clinician.
4.Produces, constant pressure on teeth and mid palatal
suture.
5. Permits patient to mitigate the pressure response.
6. As the bone deposition along suture is able to keep
pace with the expansion, it avoids an unsightly midline gap.www.indiandentalacademy.com

83.
www.indiandentalacademy.com

84.
Clinical management of palatal
expanders
• A rapid palatal expander is usually the first
appliance used when palatal expansion is
planned for a patient in the permanent dentition.
• For maximum orthopedic effect the abutment
teeth should not have undergone prior
movement. If teeth have been aligned before
placement of the expander, the periodontal
membrane usually is widened, and the likelihood
of dental rather than orthopedic movement is
increased.
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85.
Activation schedule
• 1. Schedule by Timms
– Patients less than 15 years of age: 90 degree rotation
in morning and evening
– Patients greater than 15 years of age: 45 degree
activation 4 times a day
• 2. Schedule by Zimring and Isaacson
– Young growing patients: 2 turns per day for 4-5 days
followed by 1 turn per day till expansion is achieved
– Non growing adults: 2 turns per day for 2 days, then 1
turn per day for 5-7 days followed by one turn every
alternate day till expansion is achieved
www.indiandentalacademy.com

86.
• McNamara and Burdon: they prefer once
a day activation schedule till expansion is
obtained; in order to avoid nasal distortion
which has been associated with two
expansion per day protocol
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87.
• Adequate expansion is said to be achieved
when lingual cusps of upper posteriors
approximate buccal cusps of lowers.
• The key used by the parent for expansion may
be either an extended safety key with acrylic
handle, or it may be a traditional wire key.
• After adequate expansion has been
achieved, the appliance is left in place for an
additional 3-5 months to allow for adequate
reossification of the involved sutural systems.
During this period, cold cure acrylic can be
applied to the screw to stabilize the appliance.
www.indiandentalacademy.com

88.
• Removal of the Expander: An ordinary pair
of posterior band removing pliers can be
used to remove the expander.
• Following removal, it is essential that fixed
appliances be placed on the involved teeth
within a very short period.
• Usually stabilization is achieved during
treatment using a transpalatal arch.
• If fixed appliances are not to be used
immediately, an acrylic plate is given for
full time wear.
www.indiandentalacademy.com

89.
Slow Maxillary Expansion
• The aspect of rapid expansion that was not
appreciated initially was that orthodontic tooth
movement continues after expansion is
completed, until bone stability is achieved
• It is possible for the tooth movement to allow
bony segments to reposition themselves while
the teeth are held in same relation to each other
• This is what occurs approximately in 3 months
required for bony in at the suture after rapid
expansion
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90.
• During this time, the dental expansion is
maintained, but the two halves of maxilla
move back towards each other, which is
possible because at the same time the
teeth moves laterally on the supporting
bone
www.indiandentalacademy.com

91.
Slow Vs Rapid Maxillary Expansion
When expansion was
completed, 10 mm of total
expansion would have been
produced by 8 mm of
skeletal expansion and only
2 mm of dental expansion
At 4 months, same 10 mm
of expansion would still be
present, but at that point
there would be only 5 mm of
skeletal expansion and
tooth movement would
account for 5 mm of total
expansion

92.
• Rapid activation of jack screw is therefore not an
effective way to minimize tooth movement
• Approximately 0.5 mm per week is the maximum
rate at which tissues of mid palatal suture can
adapt
• If jack screw attached to teeth is activated one
quarter turn of the screw (0.25mm) every other
day, the ratio of dental to skeletal expansion is
about 1:1
• Tissue damage and hemorrhage at suture are
minimized and a large midline diastema never
appears
www.indiandentalacademy.com

93.
• Thus a 10mm of expansion over a 10
week period, at rate of 1 mm per
week, would consist of 5 mm of dental and
5 mm of skeletal expansion
• This situation is analogous to rapid palatal
expansion 2-3 months
• Thus over all result of rapid Vs slow
expansion is similar, but with slower
expansion a more physiologic response is
obtained
www.indiandentalacademy.com

94.
• Story (AJO 1973), Ekstrom (AJO 1977) have
suggested that slow expansion procedures allow
physiologic adjustment and reconstitution of the
sutural elements over a period of 30 days.
• Oshima 1972 showed that monkeys whose maxillas
were expanded slowly (60) days showed less
evidence of tipping of abutment teeth and greater
sutural stability than monkeys that underwent rapid
expansion (10 days). Similar results were obtained
by Cotton (AJO 1978) in monkeys.
• Increased fibroblastic, osteoblastic and osteoclastic
activity seems to occur when the maxilla is widened
slowly. Slower expansion has been associated with
more physiologic stability and less relapse than
RME.
www.indiandentalacademy.com

95.
Semi rapid maxillary expansion
• Rapid displacement or deformation of the facial
bones would result in a marked amount of
relapse in the long term, whereas relatively
slower expansion of the maxilla would probably
produce less tissue resistance in the
nasomaxillary complex.
• Therefore, Iseri et al EJO 1998 suggested RME
followed by slow maxillary
expansion, immediately after the separation of
the midpalatal suture, namely, semirapid
maxillary expansion (SRME).www.indiandentalacademy.com

96.
• The schedule would be two turns each day for the
first five to six days, to open up the suture and
followed by three turns each week for the
remainder of the expansion treatment.
• This would stimulate the adaptation process in the
nasomaxillary complex and would result in
reduction of relapse in the postretention period.
• Iseri AO 2004 studied long term stability of semi
rapid maxillary expansion in 40 patients with mean
age of 14.57 years and mean followup period was
2.68 years after retention.
• The findings of this study suggested that the
dentoskeletal changes after the use of SRME
were maintained satisfactorily in the long term in
older adolescents and adults.www.indiandentalacademy.com

97.
Effects of rapid maxillary expansion
in skeletally mature patients
• Lateral tipping of posterior teeth,
• Extrusion,
• Periodontal membrane compression,
• Buccal root resorption,
• Alveolar bone bending,
• Fenestration of the buccal cortex,
• Palatal tissue necrosis,
• Inability to open the midpalatal suture,
• Pain, and
• Instability of the expansion.www.indiandentalacademy.com

98.
• However, a few reports in the literature contradict
these findings and state that nonsurgical maxillary
expansion is as successful in adults as it is in
children (Handelman AO 2000)
• Because of more complications after attempts to
orthopedically alter the transverse dimension of the
maxilla with advancing age, surgical procedures
have been recommended
• These procedures have conventionally been
grouped into 2 categories:
– Segmenting the maxilla during a LeFort osteotomy to
reposition the individual segments in a widened transverse
dimension, and
– Surgically assisted rapid palatal expansion (SARPE).
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99.
INDICATIONS FOR SARPE
• 1. To increase maxillary arch perimeter, to correct posterior
crossbite, and when no additional surgical jaw movements
are planned.
• 2. As a preliminary procedure, even if further orthognathic
surgery is planned, to avoid increased risks, inaccuracy, and
instability associated with segmental maxillary osteotomy.
• 3. To provide space for a crowded maxillary dentition when
extractions are not indicated.
• 4. To widen maxillary hypoplasia associated with clefts of the
palate.
• 5. To reduce wide black buccal corridors
• 6. To overcome the resistance of the sutures when RME has
failed.
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100.
PATIENT SELECTION
• Diagnosis
– Clinical evaluation, model
analysis, occlusograms, and radiographic
measurements have been recommended for an
accurate assessment.
– Clinical evaluation includes assessment of the
maxillary arch form and symmetry, shape of the
palatal vault, width of the buccal corridors on
smiling, occlusion, and mode of breathing
– Study models should be used to thoroughly
assess the arch form and the shape
– The most common include the indexes of
Pont, Linder-Harth, and Korkhauswww.indiandentalacademy.com

101.
• Lehman 1984 recommended an occlusal radiograph
to evaluate the ossification of midpalatal suture
• This, however, is unreliable because of the
superimposition of other bony structures and the lack
of adequate visualization of the posterior part of the
intermaxillary suture.
• Betts et al 1995 suggested that posteroanterior
cephalograms are reliable means to identify and
evaluate transverse skeletal discrepancies between
the maxilla and the mandible.
• With advent of Cone-beam computed tomography one
can generate scans that enable the clinician to
perform a 3-dimensional evaluation of the apical
bases including horizontal sections of the apical bases
at different levels. www.indiandentalacademy.com

102.
Age as criterion
• The patient’s age has been considered by most
authors and clinicians as the fundamental basis for
distinguishing the use of orthopedic expansion vs
SARPE
• However, conflicting views regarding when orthopedic
expansion is successful and when to request surgical
assistance, are found in the literature.
• Timms and Vero 1981 used 25 years as the upper
limit for recommending orthopedic expansion
• Mommaerts stated that RME is indicated for patients
younger than 12 years, and, for those over 14
years, corticotomies are essential to release the areas
of resistance to expansion.www.indiandentalacademy.com

103.
• Further confusion is added by several
case reports in which orthopedic maxillary
expanders has been shown to be
successful in much older adults. (Alpern
and Yurosko 1987, Capelozza Filho 1999)
• These authors suggested that, although
an orthopedic effect was not
observed, slow expansion results in a
combination of membranous warpage and
some sutural stretching to provide the
desired end result.
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104.
• In treatment planning and case selection, the
patient’s medical condition must be thoroughly
evaluated
• Several metabolic conditions have been linked
to sutural synostoses.
• These include
hyperthyroidism, hypophosphatemic vitamin D-
resistant rickets, and mucopolysaccharidoses
and mucolipidoses
• RME would either be unsuccessful or have
unfavorable consequences even in a
chronologically young patient with such medical
conditions. www.indiandentalacademy.com

105.
Amount of expansion
• Betts et al 1995 have recommended that the
amount of desired expansion is an important factor
in case selection for maxillary expansion in adults.
• In general, an orthodontist can camouflage
transverse maxillomandibular discrepancies less
than 5 mm with orthopedic or orthodontic forces
alone.
• When the transverse deficiency is greater than 5
mm, surgical assistance is essential.
• Although both SARPE and segmental osteotomy
are used, segmental osteotomy is reported to be
unstable, especially when more than 8 mm
expansion is desired
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106.
Two-stage vs singular surgery
• Segmental osteotomy is the preferred choice for
correction of transverse discrepancy when a single
surgical procedure is planned to correct all maxillo-
mandibular discrepancies
• On the other hand, correction of transverse
discrepancy is done as a first step with SARPE and
a separate second surgery is necessary for
discrepancies of the maxilla and the mandible in the
other planes of space.
• Bailey et al 1997 have recommended that SARPE
should be used for patients with an isolated
transverse deficiency when OME is not indicated, or
with unilateral or asymmetric narrowing of the
maxilla.
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107.
• Proponents of SARPE have also
hypothesized that post-SARPE orthopedic
forces can be applied to the maxilla, since
the 2 halves of the maxilla have been
loosened.
• These forces might be valuable in
correcting sagittal or vertical discrepancies
without additional surgery.
• This, however, has not been used
routinely because the prognosis is
uncertain. www.indiandentalacademy.com

108.
Periodontal status
• Muller and Eger 2002 introduced the concept of
periodontal biotype
• They pointed out that it is essential to record the
thickness of the gingival tissues during clinical
evaluation of the periodontium.
• Therefore, evaluations of the gingival tissues
and the biotype are essential to determine the
ability of the tissues to withstand the pressure of
orthopedic maxillary expansion;
otherwise, surgical release of the sutures is
needed to remove interferences to maxillary
expansion. www.indiandentalacademy.com

109.
Orthodontic considerations and
preparation
• The mandibular dentition should be
decompensated before surgery to allow
assessment of the amount of transverse
expansion necessary, to establish arch
coordination, and to assist in preventing
postexpansion relapse with dental interdigitation
• Before sending a patient for a SARPE, the
orthodontist must ensure that there is enough
space between the roots of the central incisors
for a midline split.
• If space is inadequate, preoperative root
divergence must be createdwww.indiandentalacademy.com

110.
SURGICAL TECHNIQUE
• The surgical technique for SARPE involving a
midpalatal split was described by Brown in 1938.
• Many surgical procedures have been designed
to resect the areas of resistance to lateral
expansion in the midface.
• The areas of resistance have been classified as
– Anterior support (piriform aperture pillars),
– Lateral support (zygomatic buttresses),
– Posterior support (pterygoid junctions), and
– Median support (midpalatal synostosed
suture).
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111.
• Initial reports described the midpalatal suture as the
area of greatest resistance to maxillary expansion.
• However, later reports highlighted the zygomatic
buttress and the pterygomaxillary junction as critical
areas of resistance.
• Kennady et al AJO 1976 evaluated the influence of
lateral maxillary and pterygomaxillary osteotomies
with and without palatal osteotomy vs unoperated
controls or palatal osteotomy alone and found
significant differences.
• They concluded that reducing or eliminating the
resistance to lateral movement by osteotomy allows
for movement of the basal bone of the maxilla.
www.indiandentalacademy.com

112.
• Timms 1981 suggested that there are 3 stages of
surgical assistance for maxillary expansion based on
the patient’s age.
– Stage 1 (median osteotomy) is performed for patients aged
25 years or older, or younger if rapid maxillary expansion
was tried and failed.
– Stage 2 (median and lateral osteotomies) is reserved for
those aged 30 years and older, and
– Stage 3 (median, lateral maxillary and anterior maxillary
osteotomies) is for patients aged 40 years and older.
• Betts and Ziccardi 2000 recommended a total bilateral
maxillary osteotomy from the pyriform aperture to the
pterygomaxillary fissure along with a midpalatal split
from the anterior to the posterior nasal
spines, sectioning all articulations and areas of
resistance—anterior, lateral, posterior and median
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113.
• Bays et al 1992 and Northway et al 2000
recommended that no attempt should be made to
separate the maxilla from the pterygoid plates to
avoid invasion into the pterygomaxillary junction.
• According to them, such a separation requires
extreme force and usually causes the plates to
fracture.
• There is no consensus about either the extent or
the procedure for SARPE.
• There are also no conclusive means to determine
the areas of resistance to lateral maxillary
expansion or ascertain an individualization of the
surgical cuts.
• The extent of surgery ideally should depend on the
areas of resistance with some individualization.
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114.
RETENTION, STABILITY, AND
RELAPSE
• The issue of long-term stability and relapse with
SARPE has not been studied in detail in the
literature.
• In general, most reports state that surgical
expansion is more stable than orthopedic maxillary
expansion
• Some authors recommended that retention is not
necessary for SARPE, and the orthodontist can
begin orthodontic treatment without a holding phase.
• The relapse rates for SARPE vary from 5% to about
25%. These rates are significantly lower than that of
orthopedic expansion, which can be as high as 63%
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115.
• The high rate of relapse associated with
orthopedic maxillary expansion is due to its use
in skeletally advanced patients.
• In a study by Berger et al AJODO 1998, both
orthopedic maxillary expansion and SARPE
were compared in an age-appropriate sample.
• The orthopedic maxillary expansion sample
comprised subjects aged 6 to 12 years, and the
SARPE group’s ages ranged from 13 to 35
years.
• These authors found no difference in the stability
of SARPE and orthopedic maxillary expansion .
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116.
COMPLICATIONS OF SARPE
• Complications associated with SARPE include
significant hemorrhage, gingival recession, root
resorption, injury to the branches of the maxillary
nerve, infection, pain, devitalization of teeth and
altered pulpal blood flow, periodontal
breakdown, sinus Infection, alar base
flaring, extrusion of teeth attached to the
appliance, relapse, and unilateral expansion.
• Palatal tissue irritation is a frequent complication
of SARPE.
• This can be either due to impingement from the
appliance or associated with a rapid rate of
expansion
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117.
Unusual complications
• The incidence of frank aseptic tissue necrosis has
been reported to be about 1.8%
• Occasionally, aberrant fractures of the maxillary
articulation are seen
• Aberrant and asymmetric fracture of the
interdental bone between the central incisors
leads to increased mobility, gingival
recession, dehiscence, and periodontal defects on
the incisors.
• Some unusual complications that have been
reported include orbital compartment syndrome
resulting in permanent blindness, bilateral lingual
anesthesia, and a nasopalatine canal cyst
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118.
Bone borne palatal distractor
• Mommaerts 1999 suggested the use of a bone-
borne titanium device with interchangeable
expansion modules rather than a conventional
tooth-borne appliance.
• According to him, conventional tooth-borne
appliances produce greater loss of anchorage
and more skeletal relapse both during and after
expansion.
• Higher incidences of cortical fenestration and
buccal root resorption are also observed with
tooth-borne appliances compared with absolute
bone-borne appliances.
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119.
• Orthodontic treatment can be initiated earlier in the
postsurgical period with the bone-borne appliances
than tooth-borne appliances.
• The application of the bone-borne distractor does
not depend on a complete dentition
• They have been reported to have greater control of
orthopedic movement than tooth-borne appliances
• The bone-borne appliances are contraindicated in
patients with extremely low palates, because the
nails of the abutment plates loosen more easily and
the distractor is not stable.
• These are also contraindicated in patients with
immunodeficiency conditions and prior radiation
therapy. www.indiandentalacademy.com

120.
Case report by Emel Sari
AO 2007
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121.
• The transpalatal distractor (TPD) allows for
maxillary expansion according to the concepts of
distraction osteogenesis
• The Transpalatal distractor applies expansion
forces high in the palatal vault and segmental
tilting in the frontal plane is therefore minimal.
• Pinto et al 2001 analyzed the immediate
postexpansion positional changes of the
maxillary halves resulting from the use of the
transpalatal distractor and concluded that the
expansion at the canine level was 1.5 times
greater than at the molar level and expansion in
the frontal plane occurs with little tipping of the
segments. www.indiandentalacademy.com

122.
When the distractor is placed on
the palate at the level of the
second premolar and
pterygomaxillary disjunction is not
performed, more expansion
occurs in the anterior part of the
maxilla than it does in the
posterior.
Matteini AJODO 2001 showed
that pterygomaxillary disjunction
and placement of the Transpalatal
distractor on the palate at the level
of the first molars result in more
parallel expansion of the maxillary
segments

123.
Conclusion
• Maxillary arch constriction or maxillary width
deficiency associated with a high palatal vault is
generally treated orthodontically by expansion of
the midpalatal suture.
• This procedure, introduced by Angell in
1860, was reintroduced during the 1960s by
Haas.
• Maxillary width deficiencies are routinely
corrected in growing patients with appliances
that help in separation of the midpalatal and
associated maxillary sutures.www.indiandentalacademy.com

124.
• However, this technique is not useful in
skeletally mature individuals.
• Alternatives in these situations include the
use of surgically assisted rapid maxillary
expansion (SARME) or a segmental
LeFort I osteotaomy in an attempt to
overcome the resistance of the closed
sutures
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125.
References
1. Haas AJ. Rapid expansion of the maxillary
dental arch and nasal cavity by opening of the
mid-palatal suture. Angle Orthod 1961;31:73-
90.
2. Bishara SE, Staley RN. Maxillary expansion:
clinical implications. Am J Orthod Dentofacial
Orthop 1987;91:13-4.
3. Hicks EP. Slow maxillary expansion: a clinical
study of the skeletal vs dental response in low
magnitude force. Am J Orthod 1978;73:121-41.
4. Timms DJ. A study of basal movement with
rapid maxillary expansion. Am J Orthod
1980;77:500-7.
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5. Pawan Gautam, Ashima Valiathan,and Raviraj
Adhikari. Stress and displacement patterns in the
craniofacial skeleton with rapid maxillary
expansion: A finite element method study. Am J
Orthod Dentofacial Orthop 2007; 132:5.e1-5.e11
6. Lokesh Suria and Parul Tanejab. Surgically
assisted rapid palatal expansion: A literature
review. Am J Orthod Dentofacial Orthop
2008;133:290-302
7. Daniela Garib, José Castanha
Henriques,Guilherme Janson, Marcos Roberto de
Freitas. Periodontal effects of rapid maxillary
expansion with tooth-tissue-borne and tooth-borne
expanders: A computed tomography evaluation:
Am J Orthod Dentofacial Orthop 2006;129:749-58
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8. Lee KG, Ryu YK, Park YC, Rudolph DJ. A
study of holographic interferometry on the initial
reaction of maxillofacial complex during
protraction. Am J Orthod Dentofacial Orthop
1997; 111:623-32.
9. Wertz RA. Skeletal and dental changes
accompanying rapid mid-palatal suture
opening. Am J Orthod 1970;58:41-66.
10.Haas AJ. Palatal expansion: just the beginning
of dentofacial orthopedics. Am J Orthod
1970;57:219-55.
11.Chung CH, Font B. Skeletal and dental
changes in the sagittal, vertical, and transverse
dimensions after rapid palatal expansion. Am J
Orthod Dentofacial Orthop 2004;126:569-75.
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12.Iseri H, Tekkaya AE, Oztan O, Bilgic S
Biomechanical effects of rapid maxillary
expansion on the craniofacial skeleton, studied
by the finite element method. Eur J Orthod
1998;20:347-56.
13.Krebs AA. Expansion of midpalatal suture
studied by means of metallic implants. Acta
Odontol Scand 1959;17:491-501.
14.Baccetti T, Franchi L, Cameron CG, McNamara
JA Jr. Treatment timing for rapid maxillary
expansion. Angle Orthod 2001; 71:343-50.
15.Pavlin D, Vukicevic D. Mechanical reactions of
facial skeleton to maxillary expansion
determined by laser holography. Am J Orthod
1984;85:498-507.
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129.
16.Geran RG, McNamara JA Jr, Baccetti
T, Franchi L, Shapiro LM. A prospective long-
term study on the effects of rapid maxillary
expansion in the early mixed dentition. Am J
Orthod Dentofacial Orthop 2006;129:631-40.
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