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Rapid Maxillary Expansion and Appliance

Intern; Vinayaka Mission’s Sankarachariyar Dental College, NH – 47, Sankari Main Road, Ariyanoor, Salem – 636308, Tamil Nadu, India, ,
Professor; Vinayaka Mission’s Sankarachariyar Dental College, NH – 47, Sankari Main Road, Ariyanoor, Salem – 636308, Tamil Nadu, India, ,
Address for correspondence:
This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
This article was originally published by Informatics Publishing and was migrated to Scientific Scholar after the change of Publisher; therefore Scientific Scholar has no control over the quality or content of this article.


The purpose of this article is to know more about the rapid maxillary expander. It produces significant changes in the maxillary arch. RME has fundamental effect on the dentofacial structures which results in major change occurring in the basal structures of the maxilla. The concept of maxillary expansion has also been extended to the nasal cavity. Early orthodontic treatment with RME is able to reduce the symptoms of obstructive sleep apnea syndrome. This technique is more suited for younger patients and faster duration of action.


Obstructive Sleep Apnea Syndrome
Rapid Maxillary Expander

1. Introduction

RME is otherwise known as Rapid palatal expander or split palate. RME produce skeletal type of expansion. It consists of enlargement of dental arch and widening of the palate. This concept was widely supported by ENT surgeons. RME is more useful in mixed dentition. It places an important role in the orthopaedic therapy. Orthopaedic expansion is the procedure by applying a lateral force against the posterior maxillary dentition producing a separation of midpalatal suture and produces increase in the transverse width of maxillary basal bone1,2.

2. Effect of the Rapid Maxillary Expansion

2.1 Effect on Maxillary Teeth

In anterior teeth, RME opens the midpalatal suture which creates midline spacing between two maxillary central teeth, Bodily displacement of tooth along its long occlusal direction of molars in the posterior teeth3,4.

2.2 Effect on Mandible

Decreases the overbite and increases the facial height of the mandible because of the extrusion and buccal tipping of the maxillary molars4.

2.3 Effect of RME in Nasal Cavity

Increase the intranasal space due to separation of the outer walls during activation of RME. Patients with narrow maxillary arch along with malocclusion can lead the OSAS. So RME is more affective in patient with OSAS2,4.

2.4 Effect on Alveolar Bone

During activation of RME because of compression of periodontal ligament the alveolar bones bends buccally5.

3. Indication

  • Unilateral/bilateral cross bite of the molars.

  • Patient with class II and class III malocclusion.

  • RME is useful for cleft lip and cleft palate patient.

  • Severe construction of the maxillary arch.

  • Poor nasal airway and allergic rhinitis4,6.

4. Contra Indication

  • Medically compromised patient.

  • Patient with poor co-operation.

  • Not accepted for deciduous dentition.

  • Handicapped patient.

  • Before completion of midpalatal suture RME is not accepted.

  • Patients with steep mandibular plane angle.

  • Crossbite of single tooth7,2.

5. Types of Appliance Used for RME

  • Removable

  • Fixed – Divided into two types

    • - A Banded

    • - B Bonded

5.1 Banded RME

  • Tooth borne and tissue borne.

  • Tooth borne.

5.1.1 Tooth Borne and Tissue Borne

  • Derichsweiler type.

  • Hass tyre.

5.2.2 Tooth Borne

  • Isaacson type.

  • Hyrax type.

5.2 Bonded Type RME

  • Cast cap splints.

  • Acrylic splints1.

6. Fixed Appliance

6.1 Derichsweiler Type

This appliance is tooth tissue and tooth borne type of appliance and also banded fixed appliance. The molar and premolar are banded. Wires are tagged and soldered onto the palatal aspect of the band. Those wires tags are inserted into a splitpalatal acrylic plate, incorporating a screw at its centre5,8,9. [Figure 1]

Figure 1.: Derichsweiler type of expansion appliance a. Wires tags. b. Premolar bands. c. Molar bands. d. Expansion screw. e. Acrylic plate.

6.2 Hass Type

The Hass type expander is a tooth and tissue borne style of appliance that consists of bands. The first molar and premolar are banded with a midline screw, incorporated into two acrylic plates which connect with the mucosa of the palate. Supported wires are extended to the anterior of the molar along with the posterior molar in order to get rigidity. Acrylic plates are used to reduce the tipping of the posterior molars. Inflammation of the palatal tissue due to contact of appliance with the palate.1,5,9 [Figure 2]

Figure 2.: Hass type of expansion appliance a. Lingual support wire. b. Premolar bands. c. Molar bands. d. Buccal support wire. e. Acrylic plate. f. Expansion screw.

6.3 Hyrax Type

The Hyrax tyre of expander is a fixed tooth borne appliances that consist of bands. The bands are connected to the first molar and premolar with Hyrax screw incorporated into the metal framework. Acrylic component are not used in the fabrication of the Hyrax appliance. Hyrax appliance is more flexible when compared to the Derichsweiler and Hass type expander1,5,9. [Figure 3]

Figure 3.: Hyrax type of expansion appliance.

6.4 Isaacson Type

Isaacson type of expander is a tooth borne appliance instead of acrylic component metal frame work is used. MINNE expander (developed at the University of Minnesota, dental school) is a type of spring loaded screw in Isaacson type of expander. The first molar and premolar are soldered and banded into the lingual and buccal aspect using metal framework. This type of expander contains coil spring which compresses the spring having nut. The Isaacson expander is activated by closing the nut which compresses the spring79. [Figure 4]

Figure 4.: Isaacson type of expansion.

7. Activation

In patient with 15 years of age 90 degree rotation can be activated twice in a day. In patients with above 50 years of age 45 degree activation is required 4 time/day. In older patient first 2 days should be two turns on each day followed by 1 turn/day for the 5-7 days and one time activation for alternative days till the acceptable amount of expansion is gained. The parent must be guided to active the screw for the younger patient. Mild pain may be felt during expansion1,9. [Figure 5(a) (b)]

Figure 5.: (a) Typical expansion screw. (b) Key used for activation of appliance.

8. Conclusion

RME is more useful in several cases with moderate to severe discrepancy and maxillary construction and also used for increase the arch length. This procedure will improve nasal respiration and may be useful approach in dealing with abnormal breathing and OSAS. The appliance used in RME is more useful for expansion of the maxillary arch with limited duration. RME is a comparatively simple and conservative method of treatment.


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