This document discusses the management of transverse discrepancies including crossbites and maxillary expansion. It begins with definitions of key terms and discusses the prevalence, etiology, diagnosis, and classification of posterior crossbites. Treatment options are provided for different crossbite classifications. The rationale, indications, contraindications, effects, and complications of maxillary expansion (RME) are outlined. Various appliances and techniques for rapid and slow maxillary expansion are described. Factors determining the appropriate type and technique of expansion are also discussed.

1. UNIVERSITY OF GLASGOW
MANAGEMENT OF TRANSVERSE DISCREPANCIES
Personal notes
Mohammed Almuzian
1/1/2013
.

2. Table of Contents
Table of Contents.........................................................................................................................................2
Transverse discrepancies, displacements, crossbites & rapid maxillary expansion RME.............................5
Crossbites.....................................................................................................................................................5
Displacement................................................................................................................................................5
Normal growth and development of the arch form and width....................................................................5
Posterior crossbites......................................................................................................................................6
Prevalence ...............................................................................................................................................6
Benefits of treating displacement ...............................................................................................................6
Aetiology of posterior crossbites..................................................................................................................6
1.Skeletal factors......................................................................................................................................6
5.Other causes..........................................................................................................................................7
Diagnosis .....................................................................................................................................................7
Classification of posterior crossbites............................................................................................................7
1.Unilateral Crossbite with Displacement ................................................................................................7
Clinical features....................................................................................................................................7
Treatment options unilateral crossbite with mandibular displacement ..............................................7
Harrison and Ashby, 2008 Cochrane , Main results: ....................................................................................7
2.Unilateral crossbite with no mandibular displacement.............................................................................8
3.Bilateral Crossbite.....................................................................................................................................8
4.Posterior mandibular displacement..........................................................................................................9
Maxillary expansion......................................................................................................................................9
Rationale for expansion treatment...........................................................................................................9
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3. General indication of the expansion.........................................................................................................9
Contra-indications of maxillary expansion................................................................................................9
Methods of maxillary expansion................................................................................................................10
Types .................................................................................................................................................10
Advantages of removable expanders ................................................................................................10
Disadvantages of removable expanders ............................................................................................10
Types..................................................................................................................................................11
Design ................................................................................................................................................11
Indications .................................................................................................................................................12
Advantages ............................................................................................................................................12
Disadvantages ...........................................................................................................................................12
Clinical Management..................................................................................................................................12
Indications of RME..................................................................................................................................15
Contraindications of RME.......................................................................................................................15
The effects of RME.....................................................................................................................................15
Side effects of the RME..........................................................................................................................16
The influence of height of RME .................................................................................................................17
Activation schedule for RME......................................................................................................................17
1.Timms..............................................................................................................................................17
2.Isaacson...........................................................................................................................................17
Slow maxillary expansion steps..................................................................................................................18
Appliances have been used for rapid and slow maxillary expansion:.........................................................19
1.Removable appliances (discussed before).......................................................................................19
2.Fixed Appliances..............................................................................................................................19
Tooth borne........................................................................................................................................19
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4. Tooth and tissue borne ( Banded, Bonded like Cast Cap Splints or Acrylic Splints)............................19
Fixed expander appliances.........................................................................................................................19
1.Bone borne..........................................................................................................................................19
2.Tooth - tissue borne appliances ..........................................................................................................19
3.Tooth borne appliances Include:.........................................................................................................19
Bonded R.M.E.............................................................................................................................................19
Technique...............................................................................................................................................22
Indications..............................................................................................................................................23
Evidence.................................................................................................................................................23
Problems................................................................................................................................................23
Factors & Yardsticks that determines the type and technique of expansion.............................................23
Stability and retention................................................................................................................................24
Treatment of scissor bite............................................................................................................................24
Appliances for unilateral maxillary expansion............................................................................................25
Anterior crossbites.....................................................................................................................................25
Prevelance..................................................................................................................................................25
Treatment of anterior crossbites................................................................................................................25
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5. Transverse discrepancies, displacements, crossbites & rapid maxillary expansion RME
Crossbites
The British standard Glossary of Dental Terms defines crossbite as follows:
• A transverse discrepancy in tooth relationship.
• In a buccal crossbite, the lower arch is wider than the upper so that the buccal cusps of the
lower occlude lateral to the buccal cusps of the upper teeth.
• Where the lower buccal teeth occlude lingually to the upper buccal teeth there is a lingual
crossbite or scissor bite.
• A crossbite may be unilateral or bilateral and may involve varying numbers of teeth.
• If the transverse relationship is cusp-cusp then it is termed cross bite tendency.
• Also used to describe reverse overjet of one or more incisor teeth.
Displacement
• When there is a discrepancy between the muscular positioning of the mandible (centric
position) and that dictated by the teeth coming into occlusion (centric occlusion), the mandible
encounters a deflecting contact and it is displaced. Displacements can be anterior, posterior or
lateral.
Normal growth and development of the arch form and width
Arch dimensions change with growth. It is therefore necessary to distinguish changes induced by
appliance therapy from those that occur from natural growth. The total growth between 4 and 17
years amounts to ~7mm. Bjork & Skieller 1974. The average changes achieved in a sample
reported by Moyers et al 1976:
1. Growth at the mid-palatal suture is the largest contributor to increase in maxillary width,
and this is normally complete by age 17.
2. Between the ages of 7 and 12 years of age, the male have more growth than female and
there is more growth in the upper (approximately 3 mm) than the lower arch (approximately 2
mm).
3. After the age of 12, little growth in arch width is seen only in males while the female
show constriction especially at intercanine area.
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6. Posterior crossbites
Prevalence
1. Affects 8-16% of population (Foster & Hamilton 1969)
2. No difference between gender and race.
3. 16-50% self-correcting (Petren 2003).
4. 80% associated with mandibular displacement
Benefits of treating displacement
• Aesthetic benefits by widening the buccal corridor
• Psychological benefits
• Creation of space to relief crowding
• Eliminate the undesirable growth modification effects of the displacement which can
result in true mandibular asymmetry (Pinto et al 1991).
• Avoid TMD in susceptible patient (weak evidence)
• Avoid exacerbation of plaque related Pd damage
• Avoid tooth surface loss
Aetiology of posterior crossbites
1. Skeletal factors
• Due purely to a mismatch in the relative widths of the arches,
• To an anterior-posterior discrepancy resulting in relative cross bite.
• True skeletal asymmetry (hemimandibular elongation…….)
2. Dental factors
3. Soft tissue factors
• Adenoid problem can cause a low tongue position with an increased lower facial height
and subsequent cross bite Aronson (1972)
• Solow and Tallgren 1969 had suggested that this effect may be produced as a result of
mouth breathing or Airway obstruction and.
4. Habits: prolonged sucking habits.
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7. 5. Other causes
1. Congenital causes: cleft lip and palate,
2. Trauma
3. Pathology of the TMJ’s
Diagnosis
1. EOE
2. IOE
3. Ceph, PA, CBCT
4. SM
5. EMG
Classification of posterior crossbites
1. Unilateral Crossbite with Displacement
Clinical features
• In most cases, the crossbite is accompanied by a mandibular shift, a so called forced
crossbite, which causes midline deviation
• There is evidence of asymmetric muscle activity and altered bite force in children with a
posterior crossbite with displacement
Treatment options unilateral crossbite with mandibular displacement
1. Encourage habit to stop
2. Selective grinding of the primary canine success rate 27-90% (Harrison and Ashby, 2008
Cochrane)
3. Posterior onlay
4. Extraction if it is associated with severely displaced single tooth
5. Expand upper arch (Harrison and Ashby, 2008 Cochrane)
Harrison and Ashby, 2008 Cochrane , Main results:
Using the search strategy seven randomised and five controlled clinical trials were identified but
following correspondence with the authors, three of the randomised and one of the controlled
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8. clinical trials were reclassified giving five randomised and seven controlled clinical trials for
inclusion in the review. For the update an additional CCT was found giving five RCTs and eight
CCTs for inclusion in this update.
Trials comparing occlusal grinding in the primary dentition with/without an upper removable
expansion appliance in the mixed dentition versus no treatment, banded versus bonded and two
point versus four point rapid maxillary expansion, banded versus bonded slow maxillary
expansion, transpalatal arch with/without buccal root torque, an upper removable expansion
appliance versus quad-helix were identified.
Occlusal grinding in the primary dentition with/without the addition of an upper removable
expansion plate, in the mixed dentition for those children who did not respond to grinding, was
shown to be effective in preventing a posterior crossbite in the primary dentition from being
perpetuated to the mixed and permanent dentitions.
No evidence of a difference in treatment effect (molar and canine expansion) between the test
and control intervention was found in the trials which compared banded versus bonded and two
point versus four point rapid maxillary expansion, banded versus bonded slow maxillary
expansion, transpalatal arch with/without buccal root torque, or upper removable expansion
appliance versus quad-helix. Insufficient data were provided in the paper comparing two point
versus four point rapid maxillary expansion to allow a formal analysis.
Authors' conclusions:
The evidence from the trials reported by Thilander 1984 and Lindner 1989 suggests that removal
of premature contacts of the baby teeth is effective in preventing a posterior crossbite from being
perpetuated to the mixed dentition and adult teeth. When grinding alone is not effective, using
an upper removable expansion plate to expand the top teeth will decrease the risk of a posterior
crossbite from being perpetuated to the permanent dentition.
2. Unilateral crossbite with no mandibular displacement
A. Usually due to underlying skeletal asymmetry eg unilateral cleft, unilat. Condylar
hyperplasia
B. Correction is seldom indicated
C. Surgery for severe cases is indicated
3. Bilateral Crossbite
A. Usually associated with a skeletal discrepancy in transverse, AP or both
B. Usually there is no displacement & no functional indication for treatment
C. Best treated with RME but you do get a lot of relapse overcorrect
D. Care should be taken to avoid the development of iatrogenic unilateral cross bite with
displacement post expansion.
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9. 4. Posterior mandibular displacement
This associated with CLII D2 and better to be treated ASAP to avoid TMJ problem
Maxillary expansion
Rationale for expansion treatment
The aim of maxillary expansion treatment is to increase the distance between to two sides of the
maxillary arch. This is achieved via:
1. Buccal tipping or bodily movement of the teeth
2. Separation of the mid-palatal suture, with induction of new bone formation. The aim of RME
is to produce a greater degree of skeletal change. This is achieved by the use of a rigid appliance
to limit tipping of the molars, and the application of heavy forces very rapidly, so as to exceed the
rate of dental movement and produce splitting of the suture.
3. The relative amounts of these changes vary depending on factors such as the type of
appliance used, rate of activation, and the age of the patient.
General indication of the expansion
1. Unilateral crossbite with displacement– Harrsion and Ashby 2001
2. Interceptive treatment of an ectopic canine (Armi & Baccetti, 2011, Bacceti 2011)
3. To provide space in mild-moderate crowding 1mm of arch expansion in the molar region
gives ~0.6mm of space for relief of crowding (O’Higgins & Lee2000). So 3mm of expansion
would allow relief of ~2mm of crowding without changing the inclination of the labial segments.
4. Adjunctive to
• Functional appliances
• Molars distalization appliance to avoid potential posterior cross bite at the end (expansion
by inner bow HG or URA)
• Reverse facial mask treatment.
5. V shaped arch in a 'thumb-sucker'
6. Combined orthodontic surgical cases for arch coordination
7. Pre-bone graft in CLP patients
Contra-indications of maxillary expansion
1. Uncooperative patient
2. In a periodontally weak dentition.
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10. 3. Severly buccally tipped teeth
4. High angle & reduced overbite
5. Convex profile
6. True skeletal asymmetry, Bishara 2001
7. Large amount of expansion required
Methods of maxillary expansion
I. Removable appliances
Types
1. URA with a midline expansion screw (Jack screws)
A. Good retention is necessary
B. URA with midpalatal screw, success rates is 50%
C. Asymmetric expansion may be produced by sectioning the baseplate so that more teeth
are in contact with it on the non-expansion side.
D. The mode of action is
• Predominantly buccal tipping of the molar teeth.
• A small amount of separation of the midpalatal suture is possible, especially in
prepubertal children, but this is unpredictable. Skieller 1964.
2. URA with Coffin springs a
A. Walter Coffin in 1877 introduced a spring called Coffin spring.
B. Coffin springs provide a continuous, as opposed to interrupted orthodontic force (with a
URA)
C. It is less well tolerated and retained
Advantages of removable expanders
• They can easily incorporate other active components such as springs,
• Can be part of a functional appliance such as a twin block.
Disadvantages of removable expanders
• They rely on patient compliance
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11. • Produce mainly dental changes.
• As buccal tipping of the molars occurs, the palatal cusps tend to drop down and this can cause
overbite reduction and increase of MMPA.
II. Functional appliances
1. Active expansion (usually with either expansion screw or palatal arch) to prevent
crossbite formation whilst a C11 molar relationship is being obtained
2. Passive expansion: Frankel appliance produces passive expansion only by removing
influence of buccal tissues with buccal shields
III. Quadhelix and the fixed W palatal expander
It is a useful intermediate upper arch expansion device and has been extensively described and
popularised by Ricketts (1979).
Types
A. Custom made: 1-0·9mm stainless steel with four helices to increase flexibility
B. Preformed ready type
• A removable or fixed quadhelix constructed of Blue Elgiloy for increased flexibility/
adjustability and an Elgiloy based system called ORTHORAMA
• Removable nickel titanium versions have also been introduced which may offer more
favourable force delivery characteristics. But study showed that the factor effect the efficiency of
the system is the size of the appliance and diameter of the wire not the material. Ingervall,1995
Design
• The quadhelix is a fixed appliance retained by bands
cemented on the permanent first molars.
• It consists of a w-shaped 1mm spring, usually stainless steel,
incorporating 4 helices to add flexibility and increase range of
action.
• The quad helix consists of a pair of anterior helices and a pair
of posterior helices.
• The portion of wire between the two anterior helices is called the anterior bridge.
• The wire between the anterior and posterior helices is called the palatal bridge.
• The free wire ends adjacent to the posterior helices are called outer arms.
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12. Indications
1. Intermediate upper arch expansion
2. Bi-helix used in mandibular arch in grossly narrowed or distorted arches, or to aid
correction of severe scissors bite
3. Expand the upper arch anteroposteriorly when its arm length
increased
4. Provide access and
space with cleft palate before bone grafting
5. Used with facemask same as RME
6. Molar derotation
7. Habit breaking effects
8. Method of attachment to align impacted teeth or to perform certain
teeth movement
9. Provide anchorage (AP and transverse)
Advantages
1. Reduced need for patient compliance because it is fixed
2. Efficiency and evidences:
• The quadhelix produces a combination of buccal tipping and skeletal expansion, typically
in the ratio of 6:1. (Frank 1982)
• Quad. (QH and RME success rates is 100%, Harrison and Ashly 2008 Cochrane review)
• Quadhelix versus buccal arch expansion — no difference in expansion achieved and
buccal arch cheaper McNally 2003
• Herold (1989) compares the use of RME, a quadhelix and a removal appliance, and came
to the conclusion that no method of expansion was substantially better than the other.
Disadvantages
1. The limited amount of skeletal change,
2. Opening of the bite due to molar buccal tipping.
Clinical Management
• The desirable force level of 400 g can be delivered by activating the appliance by
approximately 8 mm, which equates to approximately one molar width.
• Patients should be reviewed on a six-weekly basis.
• Sometimes, the appliance can leave an imprint on the tongue; however, this will rapidly
disappear following treatment.
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13. • Expansion should be continued until the palatal cusps of the upper molars meet edge-to-
edge with the buccal cusps of the mandibular molars.
• Expansion can be done intraorally using the triple peak plier.
• Retention after the expansion
A. At least three-month retention period before it is removed
B. Achieved expansion should be retained with an upper removable appliance.
C. If fixed appliances are being used, the quadhelix can be removed once stainless steel
wires are in place.
IV. Rapid maxillary expansion (RME)
History
• Angell 1860 is considered the father of rapid maxillary expansion.
• Hass during the 1950's reintroduced rapid maxillary expansion
Applied anatomy related to RME
• The maxilla together with the palatine bone forms the hard palate, floor and greater part of
the lateral walls of the nasal cavity.
• The maxilla is a paired bone that articulates with its opposite member and various other
bones including frontal, ethmoid, nasal, lacrimal, vomer, zygomatic and the palatine bones.
• The inter-maxillary and the inter-palatine sutures are collectively called the mid-palatal
suture.
• The sphenoid and the zygomatic bones have a buttressing effect resisting mid - palatal
suture opening posteriorly.
Mechanism of RME
1. It mainly used if the post teeth are buccally inclined then RME.
2. This is best carried out prior to or during the pubertal growth spurt (Baccetti 2001), as after this
time the suture becomes more heavily interlocked which may impede separation. Melsen 1975,
Some say can use on patients > 15yrs
3. The aim of RME is to produce a greater degree of skeletal change. This is achieved by the use of
a rigid appliance to limit tipping of the molars, and the application of heavy forces very rapidly,
so as to exceed the rate of dental movement and produce splitting of the suture.
4. Clinical tips: Bishara 1998
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14. A. Postpone extraction of first premolars until palatal expansion is completed because these teeth
together with the first molars are often used as abutment teeth for anchoring the appliance.
B. Avoid orthodontic movement of the maxillary posterior teeth prior to RME since Mobile teeth
may tip faster during expansion.
C. Position the screw as superiorly as possible in the palatal vault.
D. Start turning the jackscrew 15 to 30 minutes after the appliance is inserted to allow sufficient
setting time for the cementing medium
E. 2turns daily → 0.5mm
F. Creates 10-20IIb pressure across the suture
G. Microfractures of interdigitating bone spicules. Monitor the midpalatal suture with weekly
maxillary occlusal films. The suture will open within 7 to 10 days in most patients. If the suture
does not split within 2 weeks, the lack of skeletal response may result in tipping of the teeth and
possible fracture of the alveolar plates.
H. Suture opens wider and faster anteriorly because of buttress effect of distally placed
zygomaticomaxillary sutures
I. The separation of the suture can also be visualised radiographically.
J. Transient side effect: patient will experience dizziness, pain and discomfort so it is better to warn
him
K. Midline diastema opens
L. Central diastema then begins to close as a result of some skeletal relapse and stretch of the
transeptal fiber that caused some reciprocal incisors movement
M. After the expansion is completed and the screw is immobilized for 3 to 6 months and place a
palatal holding arch between the maxillary first molars to minimize relapse tendencies.
N. There appears to be no difference in the amount of expansion of the back teeth obtained when
using a banded or bonded rapid maxillary expansion brace. Harrison and Ashby, Cochrane 2008.
O. During the orthodontic treatment phase, incorporate some expansion in the maxillary arch wire.
P. In a patient with a severely constricted palate, the clinician might consider some of the following
options:
• Initiate expansion as early as possible,
• Expand the palate in two phases, For patients with narrow palates, clinicians may choose
a telescopic screw, an interchangeable screw, or construct two appliances with progressively
larger screws.
• Overexpand the maxillary arch,
• Prolong the period of fixed retention,
• Consider extraction of teeth in one or both jaws to facilitate constriction of the dental
arches,
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15. Indications of RME
1. Interceptive treatment of an ectopic canine (Armi & Baccetti, 2011, Bacceti 2011)
2. To provide space in mild-moderate crowding 1mm of arch expansion in the molar region gives
~0.6mm of space for relief of crowding (O’Higgins & Lee, 2000). So 3mm of expansion would
allow relief of ~2mm of crowding without changing the inclination of the labial segments.
3. Buccal inclined molars since RME produce more bodily movement (Herold, 1988)
4. Adjunctive with reverse facial mask treatment to disrupt the suture and to correct the
transverse discrepancy if present (Kim 1993). Vaughn 2005 disagree with that.
5. Unilateral crossbite with displacement– Harrsion and Ashby 2001
6. V shaped arch in a 'thumb-sucker' specially if skeletal expansion more than 4mm is required
7. Child with < 31mm of intermolar width at age 7yrs is unlikely to attain adequate arch
dimensions through normal growth alone
8. Combined orthodontic surgical cases for arch coordination (usually SARPE)
9. Pre-bone graft in CLP patients
Contraindications of RME
1. Uncooperative patient
2. Adult patient
3. High angle & reduced overbite
4. Convex profile
5. Severely buccally tipped teeth
6. In a periodontally weak dentition.
7. True skeletal asymmetry, Bishara 2001
8. Large amount of expansion required
The effects of RME
1. Maxillary skeletal effect:
• The opening of the mid - palatal suture is
fan-shaped or triangular with maximum
opening at the incisor region and gradually
diminishing towards the posterior part of
palate
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16. • Similar fan shaped or non-parallel opening is also seen in the superio-inferior direction. The
maximum opening is towards the oral cavity with progressively less opening towards the nasal
aspect
2. Effect on alveolar bone: The alveolar bone in the area adjacent to the anchor teeth bends slightly.
This is due to the resilient nature of the alveolar bone.
5. Effect on maxillary anterior teeth: midline spacing between the two maxillary central incisors.
The incisor separation is about half of the distance the screw is opened. By three to five months,
the midline diastema closes as a result of the transseptal fiber traction and skeletal relapse
5. Effect on maxillary posterior teeth: These teeth show buccal tipping and are also believed to
extrude to a limited extent.
6. Effect on mandible: Most authors have observed a downward and backward rotation of the
mandible following rapid expansion.
6. Effect on adjacent cranial bones and sutures: Rapid maxillary expansion not only results in
opening of the mid - palatal suture but also has far reaching effects on adjacent cranial
7. Effects of R.M.E. on nasal cavity: Following rapid maxillary expansion an increase in intranasal
space occurs due to the outer walls of nasal cavity moving apart. This increase in nasal cavity
width is maximum in the inferior region of the nasal cavity and gradually decreases towards the
superior aspect. Similar gradient is also found in an anterio-posterior direction with the greatest
increase being in the anterior region.
8. Air flow resistance is believed to reduce by 45 - 60 %, thereby improving nasal breathing.
Side effects of the RME
1. Transient complications:
• Pain & discomfort
• Patient will experience dizziness,
• Temporary diplopia
• Pressure necrosis of palatal mucosa
• Inability to activate appliance
2. Elongation of the face by
• Downward and forward maxillary movement,
• Backward rotation of the mandible
3. Buccal molar tipping and extrusion,
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17. 4. Controversial evidence: periodontal breakdown compares with just using URA or FA
5. Effects on the nose including widening of alar base width and reduced resistance to nasal
air flow. The magnitude of these changes varies and may be age-related. Cross & McDonald
2001
6. Expansion of the mandibular arch also occurs as a response to RME. McNamara 1999
The influence of height of RME
Marquis 2012 through an infinite element study showed
1. Close to the palate:
• There were extrusive tendencies when the screw was simulated above the centre of resistance of
the teeth and nearer to the palate.
• There were distal displacements when the screw was simulated close to the palate
2. Away from the palate:
• Greater amounts of buccal crown tipping were registered when the hyrax screw was far away
from the palate.
• There were mesial displacement tendencies when the screw was simulated far away from the
palate.
Activation schedule for RME
1. Timms
• For patients of up to 15 years of age, one turn rotation in the morning and evening.
• In patients over 15 years, Timms recommends half turn activation 4 times a day.
2. Isaacson
• In young growing patients, they recommend two turns each day for 4 - 5 days and later one turn
per day till the desired expansion is achieved.
• In case of non-growing adult patients, they recommend two turns each day for first two days, one
turn per day for the next 5- 7 days and one turn every alternate day till desired expansion is
achieved.
V. Slow maxillary expansion
1. Proffit 2000 describes that when RME is used,
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18. 2. Separation of the maxillary suture occurs rapidly as can be seen by the rapid development
of a midline diastema.
3. Once sufficient expansion has been obtained, the appliance is left in place to maintain the
change.
4. However, during this period the 2 halves of the maxilla tend to move back towards each
other, possibly under the influence of tension in the palatal mucoperiosteum.
5. As the appliance is still in place, the expansion is maintained, but compensatory
dentoalveolar changes occur in response to the skeletal relapse.
6. The final ratio of skeletal to dentoalveolar change is about 50:50, which is very similar to
what is obtained by expanding the maxilla more slowly using the same appliance.
7. In conclusion, Proffit suggests that slow expansion with a rigid appliance produces
the same result by a more physiological delivery of forces.
Slow maxillary expansion steps
1. Maxillary arch is expanded slowly at a rate of 0.5- 1 mm per week.
2. The forces. 2-4 pounds as against 10-20 pounds generated during rapid maxillary
expansion.
3. Take as much as 2-5 months.
4. Slow expansion has traditionally been termed dento-alveolar expansion, although some
skeletal changes can be observed.
5. The slower expansion techniques have also been associated with a more physiologic
adjustment to the maxillary expansion, producing greater stability and less relapse potential than
in rapid expansion procedures.
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19. Appliances have been used for rapid and slow maxillary expansion:
1. Removable appliances (discussed before)
2. Fixed Appliances
• Tooth borne
• Tooth and tissue borne ( Banded, Bonded like Cast Cap Splints or Acrylic Splints)
Fixed expander appliances
1. Bone borne
2. Tooth - tissue borne appliances
A. Hass type: The first premolar and molar of either side are banded. A thick
stainless steel wire of 1.2 mm diameter is soldered on the buccal and lingual
aspects connecting the premolar and molar bands. The lingual wire is kept
longer so as to extend past the bands both anteriorly and posteriorly. These
extensions are bent palatally to get embedded in the palatal acrylic. The split
palatal acrylic has a midline screw. The plate does not extend over the rugae
area .
B. Derichsweiler type: similar to Hass appliance but without buccal wire.
3. Tooth borne appliances Include:
A. Isaacson type or MINNE expander: This is a tooth borne appliance without
any acrylic palatal covering. This design makes use of a spring loaded
screw called a MINNE expander (developed at the University of
Minnesota, Dental School) .
The first premolars and molars are banded. Metal flanges are soldered onto
the bands on the buccal and lingual sides. The expander consists of a coil spring having a nut
which can compress the spring. This coil spring is made to extend between the lingual metal
flanges that have been soldered. The expander is activated by closing the nut so that the spring
gets compressed
B. Hyrax type: This type of appliance makes use of a special type of
screw called HYRAX (Hyrake expansion or Hygienic Rapid Expander).
The screws have heavy gauge wire extensions that are adapted to follow
the palatal contour and are soldered to bands on premolar; and molars.
Bonded R.M.E
1. Cast Cap Splints
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20. 2. Acrylic Splints
• It is useful when banding is difficult especially in mixed dentition when banding the D or E is
complicated. Alternatively, only the permanent first molars can be banded.
• Also it is indicated when the tipping to be controlled or when the inclination of the abutment are
different which make the insertion of the band difficult
VI. Fixed appliances
Expansion can be obtained during fixed appliance treatment in a variety of ways.
1. The use of overexpanded stainless steel archwires, typically .019x.025 or .021x.025 can
produce expansion with reduced buccal tipping as the archwire maintains torque control.
2. Expansion arches are auxiliary wires 1.13mm ss that are placed in the EOT tubes on the
molar bands and secured to the main archwire with a ligature anteriorly. They are simple to use
but will tend to produce some buccal tipping, which can be counteracted by putting buccal root
torque in the main archwire. McNally 2008 found same effect of the auxiliary AW and the Q
helix
3. Cross elastics running from the palatal aspect of upper teeth to the buccal aspect of lower
teeth can produce some transverse correction. However, there will also be a vertical component
of force which will tend to extrude molars, and is contraindicated in high angle / reduced bite
patients.
4. Self-ligation appliances: If an archwire with a larger arch form is chosen from the outset
of treatment and twinned with a low friction bracket system, significant expansion and change in
arch form is possible. However, there is no evidence that this is any more stable than any other
method of expansion.
VII. Alternate Rapid Maxillary Expansion and Constriction (Alt-RAMEC)
• A protocol of maxillary protraction developed by Liou and Tsai in 2005.
VIII. Hybrid hyrax (Wilmes 2008)
An RPE appliance was developed that utilizes mini-implants anteriorly in the
palate for skeletal anchorage. Because this device is also attached to the first
molars, it can be denominated as a bone- and tooth-borne appliance (hybrid
hyrax).
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21. IX. Microimpnat assited RME
• MARPE (Tausche, 2008) is a simple modification of a conventional RPE
appliance. The main difference is the incorporation of micro-implants into
the palatal jackscrew to ensure expansion of the underlying basal bone,
minimizing den- toalveolar tipping and expansion. The literature shows a
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22. lack of knowledge and data regarding MARPE in the orthodontic
community, yet many clinicians continue to utilize the device in practical or
educational settings. Se- veral case presentations have been published but no
studies demonstrate the influence of the MARPE on the cranium and
surrounding circummaxillary sutures.
X. Surgical assisted RME
Technique
• It is a part of distraction osteogenisis
• It involve Lefort I osteotomy with RME
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23. • Following SARPE, the maxilla should be allowed to remain stationary for five days prior to
initiation of expansion of the maxilla at 0.5mm/day (this allows capillary healing across the
osteotomy area- Ilizarov theory of distraction).
• It is better to divert the root of the central to allow surgical cut
Indications
1. Failed orthodontic expansion
2. Adult patient
3. Sever maxillary transverse deficiency >5mm
4. Extremely thin, delicate gingival tissue or presence of significant buccal gingival
recession in the canine-premolar region in the maxilla
Evidence
Surgical and non-surgical techniques: No significant difference in stability of expansion after 1 yr
Berger et al., 1998
Problems
1. PD damage at area of osteotomy
2. Root damage at area of osteotomy
3. Oronasal fistula
4. Numbness of lip and palate due to osteotomy side effect
5. Risk of nasal septum deviation
Factors & Yardsticks that determines the type and technique of expansion
1. Age
2. Aetiology
3. Buccolingual inclination of the post teeth
4. OB
5. Buccal gingivae thickness
6. The clinical condition of the teeth
7. Intermolar width measurement
• measure the distance between the most gingival extension of the buccal grooves on the
mandibular first molars
• measure the distance between the tips of the mesiobuccal cusps of the maxillary first molars; and
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24. • subtract the mandibular measurement from the maxillary measurement.
• The average differences in persons with normal occlusion are + 1.6 mm for males and + 1.2 mm
for females
• If:
1. 1-5mm can be treated by URA
2. 5-6mm can be treated with Q-helix
3. More than 6mm need RME in growing pt and SARPE in adults
4. One should overexpand the molars 2 to 4 mm beyond the required distance to allow for the
expected post fixation relapse.
Stability and retention.
1. Up to 40% relapse has been found for all three forms of active expansion (Quad-helix, URA
expansion plates, or rapid maxillary expansion), and there is no difference between them, Herold
1989.
2. Little et al., 1990 showed that 89% of expansion in mixed dent relapses.
3. Schiffman 2001 Maxillary expansion: a meta-analysis: only 2.4 mm of expansion remaining after
more than a year which was no greater than what has been documented as normal growth. There
is insufficient data to conclude that any useful expansion beyond that can be expected through
normal growth was retained.
4. A degree of overexpansion is therefore advisable in anticipation of this.
5. Stopping the cause (habit or mouth breathing)
6. Achievement of good buccal segment intercuspation may help to enhance stability of crossbite
correction.
7. The method of retention is also important, and less relapse occurs with fixed retainers than with
removable. as the rigid acrylic baseplate, removable retainers are used offers more resistance to
relapse forces than the more flexible Essix type
8. Mode of respiration. Expansion may be less stable in mouth breathers because of the lower
natural tongue position.
9. Favourable AP and transverse growth.
Treatment of scissor bite
1. Mild to moderate
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25. A. In a child, a functional appliance can be used to correct this relationship by advancing the
mandible forward and by doing so this may help correct the lingual crossbite.
B. In an adult, fixed appliances can be used with cross-elastics and an expanded mandibular
archwire, buccal crown torquing of lower posterior, expanded archwire, .
2. Sever
A. If there is a skeletal class II base relationship, mandibular advancement surgery may help correct
the lingual crossbite.
B. Surgical techniques using distraction osteogenesis for widening the mandibular arch or
constriction of maxillary one have also been described.
Appliances for unilateral maxillary expansion
Some children do have true unilateral crossbites due to unilateral maxillary constriction of the
upper arch. In these cases the ideal treatment is to move selected teeth on the constricted side. To
a limited extent, this goal can be achieved by using:
1. Different length arms on a W-arch or quad helix but some bilateral expansion must be
expected
2. URA with asymmetric sectioning of the acrylic plate and screw
3. An alternative is to use a mandibular lingual arch to stabilize the lower teeth and attach
cross elastics to the maxillary teeth that are at fault.
4. TAD can be used to hold the unaffected side and allow the conventional expansion
technique to work on the affected side. Kim , 2010
Anterior crossbites
Prevelance
In permanent dentition, 0.8% Lipton 1996
Treatment of anterior crossbites
1. If dental Xbite
A. Bodily movement use fixed appliance 2*4 appliance
B. Simple tipping movement use URA with posterior capping, Z spring, double cantilever
spring, crossed cantilever spring, screw plate.
Requirement for successful result of the treatment by URA:
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26. A. Cooperative patient.
B. Growth direction and degree.
C. Retroclined or uprighted incisors
D. The degree of AP position of the tooth in the crossbite
E. Adequate space
F. Deep or average OB
G. The LLS are aligned. If they need an alignment it is better to delay it after correction of crossbite
H. Condition and position of the opposing tooth/teeth. If lower canine, which oppose the crossbite
upper incisor is big or buccally displaced, it is better to treat it before correction of crossbite or at
the same time.
I. Position of the unerupted canine which might cause root resorption of the incisors.
2. Dentoalveolar or mild skeletal then
A. Chincap
B. Frankle 3 (Functional)
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