DIFFERENT METHODS OF ARCH EXPANSION ARE PRESENTED

1. Prof dr MAHER FOUDA
MANSOURA EGYPT
Orthodontic
arch expansion

2. It`s one of means of creating space in dental arches
Expansion can be classified into:
- rapid maxillary expansion devices
- slow expansion devices

3. Expansion devices
Rapid maxillary expansion
(RME) devices
Removable
appliances
fixed
appliances
tooth borne
appliances
Isaacson RME Hyrax RME
tooth and tissue borne
appliances
Derichsweiler
RME
appliances
Hass RME
appliance
Slow expansion devices
Screw
appliances Coffin spring Quad helix
Ni-TI
Expander

4. Rapid maxillary expansion devices
-First reported by Emerson C.Angell who used
double jack screw kind of an appliance to expand
maxillary arch by 0.25 inches in a girl of 14.5
years old for 2 weeks with a resultant midline
diastema
-Another simpler appliance without screw was used
by walter coffin who demonstrate maxillary
expansion by coffin spring

6. Effects of RME
On the maxillary teeth and alveolar bone:
- The posterior teeth used as handles to transmit
forces to the maxilla, they tend to tip buccally
due to the compression of the periodontal
ligament on the pressure side

8. -There`s distinct appearance of amid line
diastema which appears within days of
initiating RME therapy
-The diastema is generally 1/2 the distance of
the distance by which the screw is activated
-The diastema is reported to close
simultaneously within 6 months due to the
trans-septal fiber traction

10. Maxillary skeletal effects:
-The RME appliance is essentially a dento facial
orthopedic appliance, which tends to split mid palatine
suture
-It shows large individual variations to closing
ranging from 15 to 19 years of age with agrater
degree of obliteration occurs posteriorly than
anteriorly and with maximum obliteration
in the third decade of life
-So the palatine processes separate in a triangular or
wedge shape manner when viewed occlusally

12. Indications for use RME appliance:
-Growing patient with severely constricted
maxillary arches involving mouth breathing
patients
-Posterior cross bite with maxillary deficiency
-Cleft patients
-Along with face mask
-Class3 cases minor maxillary deficiency
-As apart of interceptive orthodontics

13. Types of RME appliances
Removable appliances
Fixed appliances
-tooth borne
-tooth and tissue borne

14. Removable RME appliances
More effective in mixed dentition
-
phase as the mid palatine suture hasn`t been
ossified yet
-The appliance consists of a screw in the midline
with retentive clasps on the posterior teeth
-The acrylic plate is split in the midline and
activations of the screw forces the two halves
apart resulting in expansion

15. Fixed RME appliances
Tooth borne appliances
Isaacson RME appliances
- Consists of a metal frame work soldered both
labially and palatally on first premolar and
molar bands
-A spring loaded screw called front expander is
soldered on the palatal extension of metal
framework
-On closing anut, the spring is compressed and
activation of expander occurs

17. HYRAX RME appliance (hygienic rapid expander)
-The hyrax screw has heavy wire extensions
which can be adapted to the contour of the
palate and are soldered to either metal
bands or cast cap splints or awire
framework that has acrylic splints or
embedded in acrylic splints

20. Tooth and tissue borne RME appliances
:
Derichsweiler RME appliances
-Wire tags are soldered to premolar
and molar bands, incorporated in an
acrylic plate which contains screw
in mid line

22. :
HASS RME appliance
-It has a rigid wire framework, soldered
to the first premolar and molar bands
both buccally and palatally
-The palatal extensions of 1.2 mm wire
are incorporated in an acrylic plate
containing an expansion screw in the
midline

24. ِ
activation of RME appliance
-The basic principle is to generate forces (more than
orthodontic forces) up to 10:20 pounds that are
capable of splitting the mid-palatine suture
- The screw is activated at between 0.5 to1mm per
day, resulting in 1cm expansion in 2 to 3 weeks
-Timms has suggested an activation of 90 morning
and evening for patients up to age of 15
- Above this age he suggested an activation of 45
four times a day

25. -Zimring and isaacson recommended, two turns
per day for initial 4 to 5 days followed by one
turn per day in growing individuals
- For adults he recommended two turns each for
the first two days followed by one turn per day
for the next 5 to 7 days

26. Retention following RME therapy
-Usually the same appliance is used for
retention after immobilizing the screw
using cold cure acrylic
-Alternatively the expansion can be
maintained using atranspalatal arch
(ATP)

29. Slow expansion devices
-It involves the use relatively lesser forces
(2 to 4 pounds) over longer periods (2 to 6
months)
Indications p of slow expansion:
-Correction of unilateral cross bites
-Correction of 'V' shaped arches as in thumb
suckers
-Preparation for bone grafts in cleft cases
-Minimal crowding in upper arch (1-2mm)
-Elimination of displacement

30. Appliances used for slow expansion
Screw appliances :
-These screws have a smaller pitch
and activated less frequently as
compared to screws used for RME
appliances

32. Coffin spring:
- It has been shown to split palate especially
when used in early mixed dentition period
- Ideal appliance to treat unilateral
cross bites
-It has an advantage over screw appliances in
that differential expansion can be obtained in
the premolar and molar regions

34. Coffin spring activation
-by pulling the wings apart at first in premolar
area then in molar area with the two sides at
the same plane
-Marking holes should be drilled on the two
wings and a divider should be used to measure
the amount of activation

36. Quad/Tri/Bi-Helix:

38. Ni-Ti Expanders:
-These make use of the high flexibility of
the nickel –titanium alloy to produce
gentle expanding forces in the range
of 300 to350 gm
-They are available in various sizes and
can be inserted in lingual sheaths
welded to molar bands