Rapid palatal expander wiki
A Rapid Palatal Expander (RPE) or Rapid Maxillary Expander (RME) is an orthodontic appliance that is
used to expand the maxillary arch. It consists of two tooth borne anchorage abutments bridged
together by an adjustable screw. The screw is subsequently torque to produce a bilateral force
perpendicular to the posterior arch resulting in arch expansion. RPE are used to create space in a
crowed maxillary arch and correct posterior cross bites. These appliances are used primarily in
children of mixed dentition but may also be used select adult cases.
1. History
Rapid maxillary expansion was first proposed by Angle in the 19th century. Angle was also the first to
report the use of RME to correct maxillary constriction (1). The biological mechanism of orthopedic
expansion explained by Mesnard in 1929 who published radiographic data indicating expansion of
the mid palatal suture and subsequent bone fill within 4-6 weeks (2).
Currently RPE has been used in treating cases of cleft palate and to narrow arch forms (3) (4). Also,
in patients with mature fused mid palatal sutures the suture can be opened surgically and the palate
expanded (5)
2. Types
2.1. Fixed
2.1.1.Hyrax: all metal construction, anchored by bands
2.1.2. Hass: acrylic component which is support to conform to the palate better and cause less
tipping of the molars
2.1.3.Lingual Arch
2.1.4.W arch
2.2. Removable
2.2.1. Adams clasp
2.2.2. Undercut class
3. Rational
The appliance is anchored in the patient’s mouth and the jack screw is turned by the patient once daily.
The force form the jack screw is transferred through the framework, to the molars and subsequently the
maxillary suture. The more frequently the screw is torque the greater the force. The amount of force
used depends on the type of expansion desired. There are essentially three types of expansion;
a. Orthopedic: This high force expansion is done in children of mixed dentition. Expansion
of this kind often causes a large diastema between 1.1 and 2.1 which subsequently
closes after remodeling. when the dentition is moved via bodily movement through the
ridge or tipping to expand the arch form
b. Surgical expansion: Very similar force to orthopedic expansion except the suture is
surgically opend. Is used in adult patients.
c. Orthodontic expansion: This low force expansion can be performed in both children and
adults and results in tipping or bodily movement of the dentition through the alveolar
bone. This does not involve expansion of the maxillary arch.
d. Passive:
4. Indication
4.1. Unilateral and bilateral crossbites
4.2. Dental crowding
4.3. Maxillary constriction
4.4. Mixed dentition
4.5. 8-13 years girls 8-15 males
5. Contraindications
5.1. Open bites: RPE tend to open the bite
5.2. High mandibular plane angle
5.3. Orthopedic adult patients ie slow maxillary expander is more frequently used
5.4. Spacing
6. Clinical procedure for common fixed Hyrax RPE (6)
6.1. Preatreatment workup and diagnosis
6.2. Separating elastics
Place separating elastics mesial of the upper first molar to create enough space for placement
of orthodontic bands.
6.3. Patient instructions and expectations
The procedure takes about 10min. The next visit should be scheduled in 3-5 days. For
discomfort the child can be administered acetaminophen or ibuprofen.
6.4. Band fitting
Fitting of orthodontic bands on the anchor teeth (first molars)
6.5. Impression
After band fitting take an alginate impression with the bands in place using a stock tray then
sanitize the impression.
6.6. Band removal and placement in impression
The bands are removed and placed in the impression.
6.7. Lab prescription
The prescription form must be filled and sent along with the impression to the lab.
6.8. Replacement of separating elastics
6.9. Try-in
Place the RPE in the patient’s mouth and seat the bands
6.10.
Work the jack screw
Perform two turns in one direction then two in the other to loosen the jackscrew extra orally.
This will make it easier to activate the appliance intraoral.
6.11.
Pumice teeth
Mix pumice and water to paste like consistency and apply with a rotating brush around the
surfaces of the molars and any rest areas.
6.12.
Etch teeth
37% orthophosphoric acid is placed for 15s. Cement bands to teeth
Cementation of the RPE bands with glass ionomer banding cement. Metal rests should be
covered with 0.5mm of composite.
6.13.
Pt instructions
Explain to the child and parents on the number of turns, recall appointments, oral hygiene and
diet. Tell them there will be a space between the two from teeth and that this is normal.
6.14.
Activation
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Perform one screw activation every day
If one day is missed do not turn twice on the following day
Must not play with the wire
Teeth should be brushed and flossed in the usual manner. As well rinse the mouth after
each meal
Should expect 8mm space between front teeth that will close
6.15.
Activation phase with follow up
It is important to turn the screw following the prescription schedule (1 turn every day for 30
days). After the patient and parent are instructed how to activate the screw, three ¼ turns are
made at this visit at 5 minute intervals. There after the patient makes one ¼ turn per day
The patient is seen again at the end of one week to check the progress. Activation is complete
at 30 days.
6.16.
Retention phase
Appliance is left in for 3-6 months after the last activation for bone to fill in. It is best to ligate
the screw in place after proper expansion is achieved by using composite or via metal ligature
Radiograph the patient before removing the appliance to be sure the suture has filled in with
bone.
6.17.
Removal
The appliance can be removed after the retention phase is accomplished
7. References
Bibliography
1. Treatment of irregularities of the perminant or adult teeth. Angell, EC. 1860, Dent Cosmos.
2. Immediate separation of the maxillae as a treatment for nasal impermeability. Mesnard, L. 1929,
Dent Rec, pp. 49;371-372.
3. Rapid maxillary expansion: Review of literature . Al-Battikki, R. 2001, Saudi Dental Journal, pp. Vol. 13,
No. 3,.
4. Some effects of rapid maxillary - Expansion in cleft lip and palate patients. Isaacson, RJ. 1964, Angle
Orthod, pp. 143-154.
5. Surgically-Assisted Rapid Palatal Expansion for Management of Transverse Maxillary Deficiency.
Silverstein, K and Quinn, P.D. 1997, J Oral Maxillofac Surg, pp. 55:725-727.
6. Midpalatal suture opening during functional cross bite correction. Harberson, VA. 310, s.l. : Am. J.
Orthod, 1978, Vol. 74.