fixed appliance techniques
2.Classification of expansion appliances
i) Rapid maxillary expansion appliance
Tooth born : Hyrax , Isaccson.
Tooth and tissue born : Hass , Derichsweiler ,
Arnold, IPC expander.
ii) Slow maxillary expansion appliances
W arch , Quad helix, NiTi expander, Trombone
appliance, Transforce appliance, Mobile intraoral arch
appliance, Williams expander, Srping jet, 3D modular
appliance, Begg technique , Preadjusted edgewise
4. Retention and stability.
Expansion in arch has been one of the oldest means of creating
space in the dental arches.
1. It is also one of the conservative method of gaining space.
2.It can also be used to correct the intermaxillary and dental arch
relationships primarily in transverse direction.
3.It enables correction of crossbites early in treatment.
• In 1860 Emerson C Angell placed a screw between maxillary
premolar of a girl aged 14 yrs and wider her arch in two weeks.
• In 1877 Walter coffin demonstrated the expansion of the maxillary
arch using spring which caused separation of the mid palatal suture
Pfaff, in 1929 described improved nasal function after maxillary
Haas, in 1960 reported increased nasal width, gain in arch and
lowering of mandible with bite opening.
Skeletal Expansion is
possible by opening
the mid palatal
Not possible to
expand the basal
Dento-alveolar Possible . Possible to certain
Scope of expansion in jaws
To correct lateral Malrelationships of Dental Arches
Failure of the two dental arches to occlude normally in lateral
relationship, known as lateral or posterior crossbite, may be due to
localized problems of tooth position or alveolar growth, or to gross
disharmony between maxilla and mandible.
Dentoalveolar crossbite with good apical base width (left) and
crossbite with a deficient apical base width (right).
Need for expansion
Lack of harmony between the maxillary and mandibular widths
usually is due to a bilateral constriction of maxilla.
In such cases, the muscles shift the mandible to one side to acquire
sufficient occlusal contact for mastication, causing unilateral
crossbite though the constriction is bilateral.
Rarely, there may be true unilateral crossbite due to asymmetric
lateral growth of maxilla e.g in case of hemifacial microsomia.
A more severe condition is that in which the mandibular denture
occludes completely within the maxillary arch.
On the basis of the type
On the basis of the effect by the forces
Slow / Dentoalveolar / Orthodontic Fixed
Passive - Frankel .
Rapid / Orthopedic - Fixed .
On the basis of the region to be expanded
In the lateral direction.
In AP direction – unilateral / Bilateral.
It is well known that expansion of the dental arches can be produced
by a variety of orthodontic treatments, including those that employee
Orthopedic Expansion :
Rapid maxillary expansion (RME) appliances are the best examples
of true orthopedic expansion in that changes are produced primarily
in the underlying skeletal structures rather than by the movement of
teeth through alveolar bone.
When the occlusion is shielded from the forces of the buccal and labial
musculature, a widening of the dental arches often occurs. This
expansion is not produced through the application of extrinsic
biomechanical forces, but rather by intrinsic forces such as those
produced by the tongue. Example as passive expansion are the
dimensional changes in the dental arches produced by such vestibular
shield appliances as the FR-2 of Frankel.
1.Rapid Palatal Expansion Appliances
e.g. : Haas appliance.
2. Slow Palatal Expansion Appliances
e.g. : Quad Helix ,NiTi expander etc.
3. Dentoalveolar expansion Appliances
e.g. : Conventional fixed appliances .
1. Increased anchorage and retention.
2. Minimal effects on speech
3. Continuous action over a long period of time.
4. Patient’s compliance is not required.
Advantages of Fixed Expansion Appliances
Effect of RME on Maxillary and Mandibular Complex
Maxillary skeletal effect:
When viewed occlusally, there is the opening of the midpalatine
suture was nonparallel and triangular with maximum opening at
incisor region and gradually diminishing towards the posterior part
When viewed frontally, the maxillary suture separates
Superoinferiorly in a nonparallel manner. It is pyramidal in shape
with the base of pyramid located at the oral side of the bone.
Rapid maxillary expansion appliances
Maxillary halves : Haas and Wertz found the maxilla to be
frequently displaced downward and forward.
Palatal vault: Haas reported that the palatine process of maxilla
was lowered as a result of outward tilting of maxillary halves.
Alveolar process : Because bone is resilient, lateral bending
of the alveolar processes occurs early during RME, which
rebounds back after a few days.
Maxillary anterior teeth : From the patient’s point of view, one of
the most spectacular changes accompanying RME is the opening
of a diastema between the maxillary central incisors. It is estimated
that during active suture opening, the incisors separate
approximately half the distance the expansion screw has been
opened, but the amount of separation between the central incisors
should not be used as an indication of the amount of suture
separation. This diastema is self-corrective due to elastic recoil of
the transseptal fibers.
Maxillary posterior teeth : There is buccal tipping and
extrusion of the maxillary molars. The posterior maxilla
expands less readily because of the resistance produced by
the zygomatic buttress and pterygoid plates.
Effect of RME on mandible: There is a concomitant
tendency for the mandible to swing downward and
RME and nasal airflow: Anatomically, there is an
increase in the width of the nasal cavity immediately
following expansion thereby improves in breathing. The
nasal cavity width gain averages of 1.9 mm, but can be as
wide as 8 to 10 mm.
It is important for the clinician to remember that the main
resistance to midpalatal suture opening is probably not
the suture itself, but in the surrounding structures
particularly the sphenoid and zygomatic bones.
INDICATIONS/CONTRAINDICATIONS OF RME
Rapid maxillary expansion is indicated in cases with a transverse
discrepancy equal to or greater than 4 mm and where the
maxillary molars are already buccally inclined to compensate for
the transverse skeletal discrepancy. Rapid palatal expansion has
been used to facilitate maxillary protraction in class III treatment
by disrupting the system of sutures, which connect the maxilla to
the cranial base, cleft lip and palate patients with collapsed
maxillae are also RME candidates.
Finally, some clinicians use the procedure to gain arch length in
patients,who have moderate maxillary crowding. It is contraindicated
in patients, who have passed the growth spurt, have recession on the
buccal aspect of the molars, anterior open bite, steep mandibular
plane, convex profiles and who show poor compliance.
CLINICAL MANAGEMENT OF RME
The patient/parent should be informed in advance about the upper
midline diastema during the expansion phase. This is likely to close
spontaneously during the retention period. Patients should be
instructed to turn the expansion screw one-quarter turn twice a day
(am and pm).
It appears that approximately 1 millimeter per week is the maximum
rate at which the tissue of the midpalatal suture can adapt, so that
tearing and hemorrhaging are minimized compared with rapid
Regime for screw rotation
Timms prescribed it according to the age and expected resistance
Three categories of patients according to age
Upto 15 yrs : 180 degree daily divided to two activations of 90
degrees morning and night.
Age 15 – 20 yrs : 180 degrees daily divided into four activations
of 45 degrees.
Age over 20 yrs : 90 degrees daily in two activations morning
Over 25 yrs : surgical seperation may be required.
Schedule by Issacson and Zimring
In young growing patients, 180 degree daily for 4 -5 days and
later 90 degrees daily till desired expansion achieved.
In non-growing adult, 180 degree daily for first two days, 90
degrees daily for next 5 -7 days and 90 degrees on alternate days
till desired expansion achieved.
Force levels tend to accumulate following multiple turns and can
be as high as 10 kg following many turns. Patients should be
reviewed weekly and some clinicians recommend that an upper
occlusal radiograph be taken one week into treatment to ensure that
the midpalatal suture has separated. If there is no evidence of this,
it is important to stop appliance activation as there is a risk of
alveolar fracture and/or periodontal damage. Active treatment is
usually required for a period of 2-3 weeks, after which a retention
period of three months is recommended to allow for bony infilling
of the separated suture
APPLIANCES FOR RME
These are banded and bonded appliances. The banded appliance
are attached to teeth with bands on the maxillary first molar and
first premolars. The banded appliances are hygienic as there is no
The banded RME are of two types:
1. Tooth and tissue borne .
2. Tooth borne .
It is a tooth borne appliance, which was introduced by William
Biederman in 1968. This type of appliance makes use of a special
screw called HYRAX (Hygenic Rapid Expander).
The Hyrax Expander is essentially a nonspring loaded jackscrew
with an all wire frame. The screws have heavy gauge wire
extensions that are adapted to follow the palatal contours and
soldered to bands on Premolar and molar.
TOOTH BORNE RME
They consist of only bands and wires without any acrylic
The main advantage of this expander is that it does not
irritate the palatal mucosa and is easy to keep clean. It
is capable of providing sutural separation of 11 mm within
a very short period of wear and a maximum of 13 mm can
also be achieved.
Each activation of the screw produces approximately 0.2
mm of lateral expansion and it is activated from front to
It is a tooth borne appliance without any palatal covering. This
expander makes use of a spring loaded screw called Minne
expander (developed by university of Minnesota, dental school),
which is soldered directly to the bands on first premolar and
The Minne expander is a heavily calibrated coil spring expanded
by turning a nut to compress the coil.
Two metal flanges perpendicular to the coil are soldered to the bands
on abutment teeth.
The Minne expander may continue to exert expansion forces after
completion of the expansion phase unless they are partly deactivated.
They consist of an expansion screw with acrylic abutting on
alveolar ridges. Haas, in 1970, gave the following advantages of
tooth and tissue RME
1. Produces more parallel expansion.
2. Less relapse.
3. Greater nasal cavity and apical base gain.
4. More favorable relationship of the denture bases in width and
frequently in the anteroposterior plane as well.
5. Creates more mobility of the maxilla instead of teeth.
Disadvantage of Tooth and Tissue Borne RME
These tooth and tissue borne RME tend to have higher Soft tissue
TOOTH AND TISSUE BORNE RME
The basis for the rapid expansion procedure is to produce immediate
midpalatal suture separation by disruption of the sutural connective
The rapid palatal expander as described by Haas is a rigid appliance
designed for maximum dental anchorage that uses a jackscrew to
produce expansion in 10 to 14 days. He believed that this will
maximize the orthopedic effects and forces produced by this
appliance have been reported in the range of 3 to 10 pounds.
A length of 0.045” SS wire is soldered along the palatal aspects
of the bands.
The free ends are turned back and embedded in the acrylic base
short of the bands
A jack screw is incorporated.
Banding difficult on malposed teeth as path of insertion is not
Banding and cementation difficult on deciduous teeth.
The first premolar and molars are banded. Wire tags are soldered
to these bands and then inserted to the split palatal acrylic, which
contains the jack screw.
Inman power component (IPC) rapid palatal expander
IPC is designed for orthopedic expansion along with labial alignment
of incisors . As expansion occurs, the IPC controls the NiTi open coil
spring force applied to the lingual surface of the anterior teeth. Wire
around the distal end of the lateral incisors limits the midline diastema
that often occurs during RPE treatment.
Inman Palatal Component E-Arch (Arnold) Expander
Ideal for transverse expansion of maxillary or mandibular arches
where patient compliance is a concern. A tube-like framework is
located on half of the arch which is connected to the Inman Power
Component (IPC) on the opposing side. Activation occurs by sliding
the collar anteriorly along the IPC compressing the NiTi open coil
springs against the tube.
The Bonded RPE were first described by Cohen and Silverman in
1973 . It is similar to the banded version with the exception of the
method of attachment to the teeth. This appliance is constructed
with an acrylic cap over the posterior segments, which is then
bonded directly to the teeth. The bonded appliance has become
popular because of its advantages:
1. It can be easily cemented during the mixed dentition stage,
when retention from other appliances can be poor.
2. Number of appointments are reduced.
BONDED RAPID PALATAL EXPANDER
3. There is reduced posterior teeth tipping and extrusion. The
buccal capping limits molar extrusion during treatment and,
therefore improves the vertical control, which is particularly useful
in class II conditions, as molar extrusion would cause autorotation
of the mandible backward and downward resulting in increase in
facial convexity and the vertical dimension of the lower face.
4.It provides Bite block effect to facilitate the correction
of anterior crossbite (McNamara).
It is introduced by Raymond Howe in 1982 . It Clears the palate
of acrylic, no banding, Can be used on malposed teeth where
parallel path of insertion is not possible.
There is a less error prone as bands dot have to be placed in
It is easy to make on deciduous teeth also.
SLOW MAXILLARY EXPANSION (SME)
SME procedures produce less tissue resistance around the
Circum maxillary structures and therefore improve bone formation
in the intermaxillary suture, which theoretically should eliminate or
reduce the limitations of RME.
Slow expansion has been found to promote greater postexpansion
stability, if given an adequate retention period. It delivers a constant
physiologic force until the required expansion is obtained. The
appliance is light and comfortable enough to be kept in place for
sufficient retention of the expansion. Prefabrication eliminates
extra appointments for impressions and the time and expense of
For SME, 10 to 20 newtons of force should be applied to the
maxillary region only 450 to 900 gm of force is generated, which may
be insufficient to separate a progressively maturing suture. Maxillary
archwidth increases ranged from 3.8 to 8.7 mm with slow expansion
of as much as 1 mm per week using 900 gm of force.
Difference between rapid and slow palatal expansion
In 1728, Pierre Fauchard developed the expansion arch which
was a flat piece of metal scalloped out for ideal position of teeth.
The teeth were ligated towards this position.
In 1887, Dr. Angle introduced the “E arch” i.e. the expansion
arch in which the labial wire was supported by clamp bands on
molar teeth. This arch was expanded and teeth were ligated to it.
Later molar bands were added.
Conventional fixed appliances
It is a fixed type modification of the Coffin spring. First used by
Ricketts in cleft palate cases.
It is preferred in maxilla and mandibular arch expansion where
mild to moderate expansion needed.
Wilson appliance / W - Arch
It is made up of 1mm SS wire.
The anterior part of wire should contact the teeth in crossbite.
Posterior part of wire should not extend more than 1 to 2 mm
beyond molar bands.
The wire is away form marginal gingiva and palatal tissue by 1 to
It can be opened anteriorly at the curve as well as at the
It is opened 3 to 4 mm wider than passive width .
Expansion rate is 2 mm per month until 2-3mm overexpansion can
be indicated .
Retention period is 3-4 months after expansion.
It is a modification of W-spring introduced by Dr. Robert
Ricketts in 1975.
1. All crossbites needing upper arch expansion.
2. Crowding cases needing mild expansion.
3. Class II cases needing molar distal rotation.
4. Class III cases with constricted maxillary arch.
5. Tongue thrusting and thumb sucking cases.
6. Cleft lip with cleft palate conditions – early treatment.
The incorporation of four helices into the W-spring helped to
increase the flexibility and range of activation. The length of the
palatal arms of the appliance can be altered depending upon
which teeth arch in crossbite.
It is made up 1mm SS wire either prefabricated or laboratory
Anterior bridge at the level of distal surfaces of canines.
Anterior helices are towards the palate.
Posterior helices are placed 2mm distal to the first molars.
These are sloped parallel to the palatal surface.
A Three prong plier is used.
1st bend: Anterior bridge is bent by keeping single beak anteriorly
– intermolar expansion.
2nd and 3rd bends are on the palatal bridges to expand lateral arms
and counteract mesial molar rotation.
A three-month retention period, with the quadhelix in place, is
recommended once expansion has been achieved. If fixed
appliances are being used, the quadhelix can be removed once
stainless steel wires are in place.
The desirable force level of 400 gm can be delivered by activating
the appliance by 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.
The quadhelix appliance works by a combination of buccal tipping
and skeletal expansion in a ratio of 6:1 in prepubertal children.
Quad helix with 3-4 mm ss tongue cribs soldered to anterior bridge
to correct the tongue thrust and thumb sucking habit correction.
The nickel titanium expander generates optimal, constant expansion
forces. It is introduced by Wendell Arndt in 1993.
It is a fixed – removable appliance(semifixed).
Its central component is fabricated from a 0.036"thermally activated
nickel titanium alloy. The rest of the appliance, including the anterior
arms, is made of 0.036"stainless steel. The expander may be used
simultaneously with conventional fixed appliances, requiring only
the addition of lingual sheaths on the molar bands.
The nickel titanium component has a transition temperature of
94°F. At room temperature, the expander is too stiff to bend for
The expander may be put in a freezer or cooled with gel freeze
packs until ready for placement. Alternatively, a refrigerant spray
such as ethyl chloride or tetrafluoroethane can be used immediately
prior to insertion to chill the expander, which is then wrapped in
gauze and placed in the mouth. The moist gauze insulates the
cooled expander from body temperature, thereby increasing the
The expander is available in sizes from 26mm to 44mm. In most
cases, the simplest way to determine the appropriate size is to
measure the mandibular intermolar width at the central fossae. Since
the mesiolingual cusps of the maxillary molars should occlude in
these fossae, expansion to the mandibular intermolar width will
provide optimal occlusion.
A 3mm increment of expansion exerts only about 350g of force and
the nickel titanium alloy provides relatively uniform force levels as
the expander deactivates.
If the mandibular molars are lingually inclined as a dental
compensation for a skeletal posterior crossbite, as often occurs, it is
appropriate to add another 1-2mm to the expansion requirement. In
any case, 2-3mm should be added for overexpansion . If more than
8mm of expansion is needed, two expanders must be used in
1. Select the appropriate size expander, based on measurement of
the study casts.
2. Adjust the anterior arms of the expander as needed.
3. Wrap the central component with moist gauze and place the
expander in the freezer.
4. Determine the appropriate band sizes, and fit bands (with lingual
sheaths) as usual .
5. Cement the bands with a dual or light-cured cement.
6. Remove the expander from the freezer, and with the gauze still in
place, slide the inserts into the molar sheaths.
7. Remove the gauze from the expander.
An alternative method involves assembly of the expander and bands
extraorally and cementation as one unit. This procedure is preferable
where access to the palate is restricted and insertion may be
difficult. The drawback of this method is that it requires rapid band
placement and cementation as the expander warms to oral
If the molars are rotated, the anterior arms of the expander may
not initially contact the buccal segments. It is usually not
necessary to adjust these arms until some derotation has
The rate of expansion will depend on the age of the patient.
Patients in the primary or early mixed dentition can be expanded in
One to two months, depending on the severity of the case.
Expansion in adolescents can take as long as three months, and
even longer expansion and retention times should be expected in
adults. The retention period should be 50-100% of the expansion
Advantage of NiTi Expander
2.Light continuous forces.
3.Easily adaptable in inactivated state.
4.Automatically expands to a predetermined shape.
5.Requires little manipulation by clinician.
6.Inbuilt safety system.
7.Patient can mitigate pressure responses.
The Transverse Expander has an expansion module to increase the
inter-canine width in upper and lower arch to accommodate
crowding in the labial segments, or to correct arch width in
The appliance inserts in horizontal lingual sheaths on the molar
bands and incorporates a gingival step mesial to the molar, placing
the body wire close to gingival level.
A recurved wire extends mesially from the molar sheath and may
be used to align irregular anterior teeth from the lingual aspect.
This facility is particularly useful when insufficient space exists to
place brackets on lingually displaced teeth. The space is created
first by transverse expansion before improving alignment prior to
bonding brackets on the anterior teeth.
The expansion unit is positioned lingual to the incisors and is very
effective in creating space in a crowded labial segment. However
it is equally effective in expanding inter-molar width and
widening the arch in the deciduous molar or premolar region.
The body wire extends from the expansion module to be inserted
in a horizontal lingual sheath on the molar band. Although the
force delivered to the molar is reduced by the long lever arm, it is
nevertheless an extremely efficient mechanism to increase molar
width without tipping the molars, by delivering a low continuous
force generated by the enclosed nickel titanium spring.
The Transverse Expander is provided in four sizes and the appropriate
size can be selected for use in the upper or lower arch. The inter-canine
width and inter-molar width is adjusted accordingly.
The range of action of the Transverse appliance is 8 mm. The anterior
transverse width of the appliance increases in 2 mm increments
throughout the series. The mesio-distal length also increases by 2 mm
to allow for variation in tooth width.
The trombone appliance is designed specifically to assist anterio-
posterior and tranverse arch development in mandible. Since the t
rombone appliance does not interfere with speech and is integrated
with conventional fixed appliances, it has excellent potential for both
mixed and adult treatment.
The design is based on the slide principle, with an inner tube sliding
freely within an outer tube to extend or contract the length of the
The molar section of the appliance is retained with double
lingual posts and includes a vertical tube attachment for insertion
of the trombone section of the appliance.
The appliance is preactivated to achieve the initial amount of
expansion required. The trombone appliance was activated by 1 mm
per side. Subsequent bilateral activation was achieved by replacing
the silicon compression tubing with tubing that was 1 mm longer,
once every 4 weeks to provide 1 mm activation per month until
the desired amount of space was achieved.
The distal portion of wire is recurved and retained in a horizontal
sheath on the molar band that extends mesially at the gingival level
to engage the anterior segment of the lingual arch. The absence of
frictional forces allows rapid tooth movement using gentle,
controlled lingual forces.
The MIA Mobile Intraoral Arch is a palatal and lingual appliance,
described by Dr. Bartel.
The MIA system makes the application less time consuming,
offering the advantage of inserting and removing the lingual
arches into sheaths pre-welded on bands. Easy removal and
reinsertion allow greater flexibility and control during treatment.
Mobile intraoral arch system
It is made up of .038 inch elgiloy. It is a prefabricated form with
various width are available.
A quad helix consists of the force producing transverse body, the
force generating arms, and the retention loops between them. The
transverse body starts occlusal at the sheath and crosses over the
arm lingually to allow proper gingival clearance around the neck of
the molars. In addition, the body of the arch maintains its flexibility
without significantly restricting the tongue.
It can be used with MIA curved rotation sheaths as well as straight
It is secured with wire tie or Alastik S1 force module. No soldering
Adapt arch in the mouth or on patient model. Use inactivated
for initial treatment phase.
Anterior helices: Position at first bicuspids
Posterior helices: Position at the middle of the sheaths.
MIA transverse body: Should miss the tissue by 1 mm in the
Maxilla and 2mm in the mandible. Consider future active tooth
Arch arms: Should contact the teeth as needed. Arms should contact
the teeth needing to be moved (bicuspids and molars) gingivally at
the area of the greatest circumference.
MIA arch adaptation
1. Activate with a flat nose plier and finger-pressure.
2. Verify activation amount by inserting one retention loop and
observing the relationship of the other retention loop to its sheath.
3. Repeat on opposite side to confirm.
The treatment goal always determines the amount of activation for
expansion, contraction, torque, and rotation. Heavy permanent forces
require activation in only small steps:
To avoid molar torque, place a compensatory bend in the double end
of the quad helix prior to sheath insertion.
Maximum 8 week activation parameters:
- Expansion and contraction is 3mm
- Rotation is 20 degrees
- Torque is 10 degrees
It is successful Mandibular Expansion Appliance was introduced
by Dr. Jeff Williams in 1994.
The Mandibular Williams Expansion Appliance is primarily
designed for children who are passing through the age of Mid-
Mixed Dentition, whose Mandibular arch is constricted, with
crowding evident in the newly erupted Mandibular incisors.
This Mandibular appliance utilizes two long stainless
tubes soldered to each of the lower primary second
molar bands with extensions back to contact the lingual
of the 6-year molars. An expansion screw is secured to
the molar bands by wire extensions extending to
transverse the anterior portion of the mandible.
An arc of .016 NiTi arch wire inserts into the forward ends of the
stainless tubes and, as the expansion screw is activated the NiTi
wire is moved forward to automatically uncrowded the incisors.
The .016 NiTi arch wire is glued, with a small bit of composite, to
the most lingually positioned incisor.
This wire may be replaced monthly with a slightly longer length
of .016 NiTi to maintain positive pressure against the lingual of
the incisors. In cases where the Mandibular 6 year molars are fully
erupted, they may be banded instead of the primary second
Indications for use of Williams Expansion Appliance:
Mandibular arch needing transverse correction.
Mandibular anterior crowding.
The Mandibular Williams Expander is adjusted by turning the
screw one turn(= 0.25mm ) weekly twice. The expansion is
continued until the proper transverse cuspid position is
At times, it may be necessary to replace the .016NiTi wire with a
stronger wire. Simply remove the original wire from the
appliance, measure the new wire, replace the shorter wire with the
Then finish by gluing the new wire to the lingual surface of the
most lingually displaced tooth. If needed, the appliance can be left
in place until the Mandibular Fixed-Removable Lingual Arch
(FRLA) is fitted to the mandibular 6-year molars for retention.
It is prefabricated appliance consist of active component madeup
of Niti spring , extended components are madeup of stainless steel
The spring jet offers a lighter consistent force transferred through
the use of NiTi springs.
Activation period is every two weeks 90 degrees turn, done by
using an allenwrench to tighten the screw in the lock
mechanism to hold the compression.
Niti coil spring delivers the 400 grams of force slow, controlled
arch expansion for patients with collapsed arches or crossbites.
Appliance installation procedure :
1. Bend the wire segment vertically into molar lingual sheath.
2. Cut to the tube to length allowing 1 mm for the bayonet wire entry.
3. From the double back , seat in sheath and check passive fit and
4. Finish the anterior wire segment for desired corrections keeping as
close to the gingival margin as possible.
Forming a bayonet bend
1.Layfree end on the director tube, mark and bend vertically to the
2.From the double back insert free end in director tube and double
back in sheath.
3. Check passive fit and finish the anterior segment.
Dr. William Wilson and Robert Wilson introduced a new
‘convertible’ appliance system in which many appliances can be
fitted through a single attachment.
3D Modular lingual tube is the key element.
It is a dual vertical tube which provides good control over molar tip,
torque and rotation.
There are 5 different modules of designs that can be fitted precisely
into these tubes
3D Quad Helix
3D Palatal Arch
3D Lingual Arch
3D Modular appliance
The 3D Quad helix has 2 twin posts which produce friction lock
security with the plugs of a 3D adapter tubes.
It is made of .038 blue elgiloy wire either prefabricated (6 different
sizes) or laboratorary constructed.
3D quad helix
The 3D Quad-Helix very precisely allow the orthodontists control
the amount of forces employed and control molars on the three
planes of the space, strongly increasing movements control.
Dr .Wilson recommends installing the appliance, at first patient visit,
absolute passive to malocclusion and starting to activate the 3D
quadHelix on a second visit.
New activations should be posted on 40 to 40 days period, on majority
of cases the activation can not exceed 1 to 2mm in order to keep case
ADAPTATION OF 3D QUAD HELIX
Tightening the posts
After use 3D Quad Helix can be cut between the helices and posts to give
This can be used as BUCCAL EXPANDER for Cuspid amd Bicuspid expansion
Resiliency of the wire reduces countermoment reaction of molars.
3D PALATAL ARCH
It is an advanced design with
As an expansion appliance it
is used for both bilateral and
3D LINGUAL ARCH
Unilateral molar expansion
Buccal root torque on non movement
side along with buccal crown tip
on expansion side
.018” Truchrome wire soldered to
lingual arch for buccal / anterior
Since there is a tendency for the anchor molars to contract and tip
lingually during the first stage of treatment, hence the archwire
should be made greater than the dental arch width this is called
“expansion for prevention”.
In considering the initial .016 premium archwire for a bicuspid
1. If the dental arch width is satisfactory, the wire should be made
2-3mm wider at each cuspid and 8-10 mm at the molar region.
2. If the dental arch requires expansion, the arch wire should be made
4-6mmwider at the cuspid and 15-25mm at the anchor molar.
3. If a bilateral cross bite is present the archwire is made 25-40 mm
wider at the side where cross bite is present.
Arch expansion is a mass buccal movement in which the arch
wire moves both buccal segments buccally and at the same time
change the anterior curvature.
Expansion with Archwires
Significant expansion may be produced by using overexpanded
stainless steel archwires, particularly those with a large dimension
for example, 0.021" x 0.025".
The archwire should be overexpanded by approximately 10 mm.
One advantage of this technique may be that less buccal tipping of
the molars occurs during expansion as the rectangular archwire
maintains torque control.
Pre adjusted edgewise Technique.
Expansion arches, also known as jockey arches, are auxiliary wires
that can be easily and cheaply constructed at the chair side and
incorporated into a fixed appliance during treatment.
The expansion arch, which can be made from 0.019" x 0.025"
rectangular stainless steel or a larger round steel wire with a
diameter of 1–1.13 mm, runs over the main archwire and is inserted
into the extra-oral traction tubes of the first molar bands posteriorly
and secured anteriorly with a ligature.
Some operators prefer to bend the wire into the buccal sulcus in
order to reduce its visibility.
The advantages of using expansion arches are that their
construction is cheap and can be carried out easily at the chairside
without having to change the molar bands.
Expansion is likely to be produced by a degree of molar tipping
and this may be reduced by incorporating molar buccal root torque
into the main rectangular archwire.
To produce maxillary expansion, cross elastics run from the palatal
aspect of one or more of the maxillary teeth to the buccal aspect of
one or more of the mandibular teeth.
Recommended force 150-210 grams.
In addition to producing lateral forces, a vertical force vector is also
produced which tends to cause molar extrusion. This can be
detrimental in patients with a reduced overbite or increased face
To limit the degree of molar tipping, cross elastics should only be
used in conjunction with rectangular stainless steel archwires.
Success with this technique is dependent on good patient
NiTi arch wires are available in preformed arch forms.
An over expanded arch form is selected.
Because of its Shape Memory and Superelasticity features, a
slow continuous force is applied which causes expansion to the
original shape of wire.
The invisalign System is proprietary to Align Technology.
The clinician sends a rubber base impression (polyvinyl
siloxane) to Align Technology laboratories with copies of
radiographic films, photographs, and a detailed treatment plan.
In this system, the clinician forms a diagnosis, plans the treatment,
and communicates this desired plan through the internet to laboratory
technicians who refine these communications via the Computerized “
ClinCheck “, until the clinician is satisfied with the treatment plan.
Aligners are then fabricated and shipped to the treating clinician.
After final approval, the treatment sequence is divided into a
series of algorithmic stages. Each stage has a maximum tooth
movement potential of 0.25 mm per appliance.
Stage models are created using computer aided process called
Individual appliances (aligners) are made from the computer-
generated models of each stage and 25 to 30 appliances may be
needed for the resolution of a case.
Buccal expansion, in the range of 2 to 4 mm, can be achieved with
this appliance to provide space for crowded anterior teeth or to
change archform. It is likely that this expansion is largely of a
tipping nature, however, if bodily expansion is required, this may
be specified (usually as an overcorrection) as the goal for
treatment into the computer plan initially.
This appliance, as is true of most removable appliances, is
relatively efficient at tipping movements. Patients who usually
progress most rapidly are those that have required primarily
tipping of their crowns. Anterior tooth alignment achieved by
proclining of anterior teeth is predictably accomplished, provided
appropriate overcorrection is done for accompanying rotations or
STABILITY OF CROSSBITE CORRECTION
The factors which may be important in enhancing the
stability of maxillary expansion include:
Achievement of good intercuspation;
Alteration in tongue position.
Expanding the maxilla in some cases may allow the
tongue to adopt a higher resting position which may
help to maintain increases in transverse arch
Mode of respiration : Expansion may be less stable in
mouth breathers because of the lower natural tongue
Retention: Retainers should be constructed from acrylic
and the Hawley type is recommended. The more flexible
Essix type of retainer may not have adequate rigidity to
counteract relapse forces.
Most of the borderline cases which once were considered for extraction
are now being attempted through non extraction approach with required
space being provided by arch expansion.
Expansion can be done along with fixed mechanotherapy but it can
questionable how much expansion can be takes place. In any fixed
mechnotherapy only 2 to 3 mm expansion can be carried out. It is
indicated only in mild expansion required cases. More than 3mm
expansion required then we go to rapid expansion methods.
Before treatment is commenced, it is essential that the prognosis
for stability of correction is assessed. The main factors
influencing stability have been stated. owing to the high relapse
potential of transverse expansion, it is important to achieve a
degree of over correction and provide adequate retention.