This document discusses rapid maxillary expansion (RME), a technique used to widen the upper jaw. It describes the 8 stages of dental development and various RME appliances such as the Hyrax, quad helix, and removable plates. RME should be initiated before midpalatal suture ossification. It effects include widening the maxilla up to 10mm and downward/backward mandibular rotation. Activation is usually 0.5mm per day and retention is required for 3-6 months after expansion. Complications are rare if performed correctly.

1. DR CHANDRIKA KATTI
Reader, Dept Of Orthodontics.
Navodaya Dental College, Raichur.

3. Eight relevant stages of dental development
A – Calcification if single occlusal points without fusion of
different calcifications
B – Fusion of the materialization points the contour of the
occlusal surface is recognizable

4. C – Calcification of the crown is
complete: beginning of dentin deposits.
The pulp chamber is curved, and no
pulp horns are visible.
D - Crown formation is complete up to the cement enamel junction.
Root formation has commenced. The pulp horns are beginning to
differentiate, but the wall of the pulp remain curved.
E – Root length shorter than crown height .The walls of the pulp
chamber are straight, and the pulp horn have become more
differentiated than in the previous stage .In molars the radicular
bifurcation has commenced to calcify.

5. F – Root length larger than crown
height the walls of the pulp chamber
now form an isosceles triangle. In
molars the bifurcation has developed sufficiently to give the root a
distinct form.
G – Root formation finished. Apical foramen still open, the walls of the
root canal are now parallel. In molars only the distal root is rated.
H – Apical foramen is closed the periodontal membrane surrounding
the root and apex is uniform in width throughout.

6.  Expansion of the palate was first achieved
by Emerson C Angell in 1860.
 Rapid maxillary expansion-
Also known as rapid palatal expansion or
split plate. It is a skeletal type of expansion
that involves the separation of the mid-
palatal suture and movement of the
maxillary shelves away from each other.

8.  Applied anatomy-
The inter-maxillary and inter palatine
sutures are collectively called as mid-
palatal suture.
Rapid maxillary expansion should be
initiated prior to the ossification of mid
palatal suture.

9.  Indications-
-Posterior cross bite associated with real or
relative maxillary deficiences.
-Class 3 malocclusion of dental or skeletal origin.
-Cleft palate patients.
-In cases requiring face mask therapy.
-Medical indications like nasal stenosis, septal
deformities, ear and nasal infections.

10.  Diagnostic aids-
Case history, clinical examination and study
models, maxillary occlusal radiographs,
P A cephalogram .

11.  Effects of R M E-
- Maxillary skeletal effect
maxillary posterior teeth are used as
handles to apply a transverse reciprocal
force so as to open the mid palatal suture.

12. -Amount of expansion achieved
Increase in maxillary width upto 10mm
-Effect on alveolar bone
Alveolar bone bends slightly

13.  -Effect on maxillary
anterior teeth
-Effect on maxillary
posterior teeth

14. -Effect on mandible
Most authors have observed downward
and backward rotation of mandible.
-Effect on adjacent cranial bones and
sutures
-Effect on nasal cavity

15.  Types of appliance-
1.Removable appliance-
Split acrylic plate with midline scew
2.Fixed appliances –
a. Tooth and tissue borne-
-Derichsweiler type
-Hass type
b. Tooth borne –
-Isaacson type
-Hyrax type

17.  Bonded RME-
alternate design of the appliance would to
have a splint covering variable number of
teeth on either side to which jack screw is
attached
Splints can be of two types-
Cast acrylic splints
Acrylic splints

18.  Description of expansion screw-
consists o oblong body divided into halves.
Each half has a threaded inner side that
receives one end of a double ended screw.
The screw has a central bossing with four
holes..The turning of the screw by 90 degree
[one turn] brings about a linear movement of
0.18mm.

20.  Activation schedule-
By Timms
for patients upto 15 yrs , 90 degree of
rotation in morning and evening .45 degree
activation 4 times a day.
By Zimring and Isaacson
in young patients, two turns each day for 4-5
days and later one turn per day till the
desired expansion achieved. In adults, two
turns each day for first two days one turn
per day for next 5-7 days and one turn every
alternate day.

21.  Treatment evaluation-
Midline diastema.
Contra indications-
-single tooth cross bites
-un cooperative patients
-after ossification of mid palatal suture
-skeletal asymmetry of maxilla and mandible.
-vertical growers with steep mandibular
plane angle.
-periodontally weak dentition.

22.  Retention following RME-
not less than 3-6 months.
Surgical procedures –
Palatal osteotomy
Lateral maxillary osteotomy
Anterior maxillary osteotomy

23.  Clinical tips-
-Oral hygiene instructions should be given
-Orthodontic movement of the anchor teeth
should be avoided prior to rapid maxillary
expansion.
-Patient should be trained to use the key
-Maxillary occlusal radiographs taken at
regular intervals.
-Immediate effects of premature appliance
removal include dizziness, pressure at the
bridge of nose, eyes, blanching of soft
tissues under eyes.

24.  Slow expansion-
maxillary arch expanded slowly at a rate of
0.5-1mm per week.
the forces generated is much lower i.e 2-4
pounds as against 10-20 pounds generated
by RME.

25.  Appliances used for slow expansion-
 -Coffin spring
 -Jack screw
 -Quad helix.

28. QUAD HELIX The Quad Helix is one of several types of
appliances that are used for expansion of the upper jaw.
It usually must be left in the mouth for 6-9 months to
allow the jaw to grow laterally with the expansion.

29. Removable orthodontic apparatus
(expansion plate)

30. Palatal Expander
The upper jaw bone (maxillae) is made up of two bones
connected by a suture in the middle. This suture does
not close until the early teenage years. Therefore, the
palatal expander can be used to widen the upper jaw
bones to correct crowding, arch constriction, and cross
bites.
This appliance will be turned once a day for a
prescribed amount of turns. During this process a gap
will open between the two front teeth as the suture is
widened. This gap will close by itself as soon as the
expansion is completed. After expansion, the expander
must stay in place for 6 months for the upper jaw bones
to grow back together and form a new suture.

31.  Schwartz
(2 way appliance) Is used when only 2
directional expansion is needed. This
Appliance is used to expand the upper
arch laterally

32. Hyrax (Rapid Palatal Expander) with
palatal expansion screw cemented in
place.

33.  3-way Appliance
This appliance is used to expand the upper arch in 3 directions, the
front forward and the back transversely. This appliance achieves
arch expansion to eliminate crowding and an optimal relationship to
the lower jaw.

34. Quad Helix with lingual expansion
arms.

35. Upper Schwarz expansion appliance
with finger spring.

36. Blue Grass Appliance is used to
correct finger and thumb sucking
habits.

37. Tongue Fence Appliance used to
control tongue thrusting
or to prevent thumb sucking.

38. Rapid Palatal Expander (RPE)—
This appliance is used to expand
the upper jaw