ORTHODONTICS

1. ARCH
EXPANSION
UNDER THE GUIDANCE OF
DR. MRIDULA TREHAN

2. CONTENT
 Historic Review
 Indications for maxillary expansion
 Classification
 Rapid maxillary expansion
 Slow expansion

3. LEARNING OBJECTIVES
The students should acquired the following
knowledge:
 Classification of expansion
 Rapid maxillary expansion
 Slow expansion

4. HISTORIC REVIEW
 Expansion of the palate was first achieved
by Emerson C Angell in 1860
 Walter Coffin in 1877 introduced a spring
called Coffin Spring for the purpose of
expanding the arch.

5. INDICATIONS FOR
MAXILLARY EXPANSION
 Crossbites or maxillary transverse
deficiency
 Mild crowding
 Along with functional appliance treatment
 Skeletal Class III malocclusion
 Distal molar movement
 Surgical orthodontics

6. CLASSIFICATION
 According to rate:
a) Rapid
b) Slow
 According to tissues:
a) Dental
b) Skeletal

7.  Classification of expansion by McNamara
1. Orthodontic or dental expansion
2. Orthopedic or skeletal expansion
3. Passive expansion

8. RAPID MAXILLARY EXPANSION
 Also known as Rapid palatal expansion or
split palate.
 Skeletal type of expansion.
 Father of rapid maxillary expansion-
Emerson C. Angell.

9. APPLIED ANATOMY
 Inter-maxillary and inter-palatine sutures
are collectively called the mid-palatal suture
 Age at which mid-palatal suture ossifies-16
years in girls and 18 years in boys (Melsen)

11. INDICATIONS FOR R.M.E.
1) Posterior crossbite
2) Cl. III malocclusion

12. 3. Cleft palate patients with collapsed
maxillary arch
4. Used along with face mask
5. ENT problems like nasal stenosis,
poor nasal airway, recurrent ear and
nasal infection etc.

13. DIAGNOSTIC AIDS
 Case history
 Clinical examination
 Study models
 Maxillary occlusal view radiograph
 P.A. Ceph

14. THE EFFECTS OF R.M.E.
 MAXILLARY SKELETAL EFFECT:
Opening of mid-palatal suture is fan-
shaped or triangular with max opening at
incisor region and gradually decreases
toward the posterior part of palate.

15.  Similar fan shaped opening is also seen in
supero-inferior direction with maximum
opening towards oral cavity and
progressively less towards nasal cavity

16.  AMOUNT OF EXPANSION ACHIEVED:
Upto 10 mm increase in maxillary width.
Rate of expansion-0.2-0.5mm per day

17.  EFFECT ON ALVEOLAR BONE: Bends slightly.
 EFFECT ON MAXILLARY ANTERIOR TEETH:
Appearance of a midline spacing. Incisor
separation is about half the distance the screw is
opened. Midline diastema closes by 3-5 months.
 EFFECT ON MAXILLARY POSTERIOR
TEETH:They tip buccally and extrude.

18.  EFFECT ON MANDIBLE:Downward and
backward rotation of Mandible leading to an
increase in mandibular plane angle.
 EFFECT ON NASAL CAVITY: Increase in
intra-nasal space. Air flow resistance
decreases by 45-60% thereby improving
nasal breathing.

19. TYPES OF APPLIANCES USED
1.Removable appliances
2. Fixed appliances
a.Tooth borne
b.Tooth and tissue borne

20. FIXED APPLIANCES
 TOOTH BORNE:
1.Isaacson type
2.Hyrax type
 TOOTH AND TISSUE BORNE:
1.Derichsweiler type
2.Hass type

21.  Isaacson type
 Uses a spring loaded screw called a
MINNE expander.

22.  HYRAX TYPE:
 Hygienic rapid expander

23.  TOOTH AND TISSUE BORNE:
 DERICHSWEILER TYPE

24.  HASS TYPE:

25. BONDED R.M.E.
 Splints are bonded to teeth
 Of 2 types:
1)Cast Cap Splints:Made of Ag-Cu alloy
2) Acrylic splints

26. DESCRIPTION OF A TYPICAL
EXPANSION SCREW
 PITCH OF SCREW: It is the extent to
which the 2 halves of the base plate move
for each full turn of the expansion screw.
Normally it is 0.8mm.
 The turning of screw by 90 degree (i.e. 1/4
turn) brings about a linear movement of
0.18mm

27. ACTIVATION SCHEDULE
 SCHEDULE BY TIMMS
 Upto 15 years-90 degree rotation in
morning and evening.
 Over 15 years- 45 degree activation 4
times a day.

28.  SCHEDULE BY ZIMRING AND ISAACSON:
 In growing patients:2 turns per day for 4-5 days
and then 1 turn per day till desired expansion is
achieved.
 In non growing patients: 2 turns per day for first 2
days, 1 turn per day for next 5-7 days and 1 turn
every alternate day till desired expansion is
achieved.

29. TREATMENT EVALUATION
DURING R.M.E.
 Midline diastema
 Maxillary occlusal radiograph
 P.A. Ceph

30. CONTRAINDICATIONS OF R.M.E.
 Single tooth crossbites
 Uncooperative patients
 Ossification of mid-palatal suture
 Skeletal asymmetry of maxilla and
mandible
 Vertical growth pattern
 Periodontally weak dentition

31. RETENTION FOLLOWING R.M.E.
 Not less than 3-6 months
 Screw immobilized by cold cure acrylic
 Removable or fixed retainers (TPA)

32. SURGERY AS AN ADJUNCT
 In girls over 16 years and in boys over 18
years of age.
 Palatal osteotomy
 Lateral maxillary osteotomy
 Anterior maxillary osteotomy

33. SLOW EXPANSION
 Maxillary arch is expanded slowly at the
rate of 0.5-1mm per week.
 Forces generated are 2-4 pounds as
against 10-20 pounds generated during
R.M.E.
 T.t completed in 1-2 weeks in R.M.E. and in
2-5 months in slow expansion
 Termed dento-alveolar expansion

34. APPLIANCES USED FOR SLOW
EXPANSION
 JACK SCREWS:Have a smaller pitch than
R.M.E

35.  COFFIN SPRING: Designed by Walter
Coffin
 1.25 mm thick wire

36. QUAD HELIX
 .038” wire
 Described by Ricketts

38.  ARCH EXPANSION USING FIXED
APPLIANCES:
1) By using expanded arch wires-
 0.021”x0.025”
 Wider by 10-12mm
 Rectangular wire maintains torque control

39. 2) Use of quad helix
 Quad helix or TPA can be used along with
fixed mechanotheraphy.

40. 3) Use of auxiliary arches
 0.019”x0.025” expanded rectangular SS
wire runs over the main archwire and is
inserted into the headgear tubes of the first
molar bands posteriorly and secured
anteriorly with a ligature.
 Known as expansion arches or Jockey
arches

42. W ARCH
 0.036” SS wire
 Soldered to bands on upper 6
 Extends from 6 to 3
 Kept 1 to 1.5 mm away from palate.
 Activated by expanding the appliance by 4-6
mm prior to insertion.
 Anterior expansion is achieved by widening the
free arms of the W arch prior to cementation

43. Fig: W arch

44. Ni-Ti EXPANDERS
 Developed by Arndt in 1993
 Action made possible by properties of
shape memory and thermal transition
temperature(84 degree F)
 0.035”diameter NiTi transpalatal loops
 0.032” SS wire for lateral expansion in
canine and premolar region

45. Fig: NiTi expander

46.  Come in 8 different inter molar widths from
26 to 47 mm
 A size that is 3 mm wider than the
transverse distance between maxillary 6
should be selected
 Inserted into lingual sheath after cooling
them

47. BIBILOGRAPHY
 Adkins , Nanda, and Currier: Arch
perimeter changes on rapid palatal
expansion. Am J Orthod 1990; 194-199
 Bjerklin K, Kurol J: Ectopic eruption of
maxillary first permanent molars: Etiologic
factors. Am J Orthod 1983; 84:147-155
 Canut J, Rega C: Morphological analysis of
cases with ectopic eruption of maxillaary
first permanent molars. Euro J Orthod 1983
; 5: 249-253

48.  Dr . James P. Moss : Rapid expansion of
maxillary arch. J Clin Orthod 1968; 215-223
 Haas : JCO interviews : Dr. Andrew J. J
Clin Orthod 1973; 227-245
 Haas : Palatal expansion : Just the
beginning of dentofacial orthopedics. Am J
Orthod 1970; 219-255
 Haas : Long term post treatment evaluation
of rapid palatal expansion. Angle Orthod
1980; 50:189-217

49.  Jacobs : Control of transverse dimension
with surgery and orthodontics. Am J Orthod
1980; 284-306
 Langford : Root resorption extremes
resulting from clinical RME. Am J Orthod
1982; 371-377
 Wertz RA. Skeletal and dental changes
accompanying rapid midpalatal suture
oprning. Am J Orthod 1970; 58: 41-66