Indian Journal of Dental Research

: 2011  |  Volume : 22  |  Issue : 5  |  Page : 734-

eRME - Rapid Maxillary Expansion in the economic way

Sonali Mahadevia, Nozar Daruwala, Krishnamurthy, Malay Vaghamshi 
 Department of Orthodontics and Dentofacial Orthopaedics, Ahmedabad Dental College and Hospital, Ahmedabad, India

Correspondence Address:
Sonali Mahadevia
Department of Orthodontics and Dentofacial Orthopaedics, Ahmedabad Dental College and Hospital, Ahmedabad


Aim and Objectives: Rapid Maxillary Expansion constitutes a routine clinical procedure in orthodontics, involving separation of mid-palatine suture which is usually done with help of the Hyrax screw. However, because of its high cost, the use has been limited, especially in institutions. So, the purpose of this study was to construct an economical device which can expand the maxillary arch in growing patients. Materials and Methods: Six patients having constricted maxilla and posterior skeletal crossbite were randomly selected from the Department of Orthodontics. A unique, easy and simple alternative device for expanding the maxillary arch called economic Rapid Maxillary Expander (eRME) has been fabricated at about one-tenth the cost of the conventional Hyrax. Pre- and post-treatment effects were statistically tested by using paired t-test at 0.05 level of significance. Results and Conclusion: The study results showed an average expansion in canine, premolar and molar regions of 4.4 mm, 6.8 mm and 9.4 mm, respectively, having significant difference pre-and post-treatment. Thus, it shows that maxillary expansion is efficiently possible with the application of this newly constructed device named eRME. This appliance also acts as a fixed retainer to avoid relapse, hence negating the need for a separate retainer.

How to cite this article:
Mahadevia S, Daruwala N, Krishnamurthy, Vaghamshi M. eRME - Rapid Maxillary Expansion in the economic way.Indian J Dent Res 2011;22:734-734

How to cite this URL:
Mahadevia S, Daruwala N, Krishnamurthy, Vaghamshi M. eRME - Rapid Maxillary Expansion in the economic way. Indian J Dent Res [serial online] 2011 [cited 2023 Sep 29 ];22:734-734
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Full Text

Expansion of the maxillary arch to correct transverse skeletal and dental discrepancies and to reduce intra-arch crowding is an accepted method of treatment first outlined by Emerson Collon Angel in 1860 and popularized by Haas 100 years later. [1] The use of Rapid Maxillary Expansion (RME) procedures has increased in the recent years, and conclusive radiographic and microscopic evidence of mid-palatal suture separation has been reported by numerous studies. [2],[3],[4],[5],[6],[7],[8],[9] In this skeletal type of expansion, the major resistance to maxillary expansion apparently is not the mid-palatal suture but the remainder of the articulation. [9]

An increase in maxillary width of up to 10 mm can be achieved by RME and skeletal changes are approximately 50% of the total change. [10],[11],[12] Rate of expansion is 0.2-0.5 mm/day. [13]

Since a long time, various appliances have been developed to create maxillary expansion, ranging from the basic removable acrylic appliances with a midline screw to the banded or bonded expansion devices.

Later, Hyrax came into practice and has proved to be an efficient and hygienic appliance, but it is not economical enough to be used, especially in institutions. So, a new appliance was fabricated in the Orthodontic Department of our college at about one-tenth the cost of the conventional Hyrax and was named economic Rapid Maxillary Expander (eRME). This new appliance provides excellent features of Hyrax with the advantage of low cost.

 Materials and Methods

Materials required

The materials required were 14 mm Jack screw with pitch 0.86 mm, flux and solder material, band material (0.180″ × 0.005″), and 18-gauge (0.044″) stainless steel (SS) wires, and acrylic resin (cold cure).

Patient selection

A total of six patients were randomly selected from the Department of Orthodontics. Out of these, four were females and two were males, with an average age of 12 ± 0.89 years.

Inclusion criteria

The age ranged between 10 and 13 years. Mid-palatine suture was patent with constricted maxilla and posterior skeletal crossbite. [14],[15] To ensure this, an occlusal radiograph was taken. All the teeth were periodontally sound. Diagnostic criteria included Ashley How's analysis, Pont's index, Korkhaus proposed index and cephalometric analysis.

Exclusion criteria

Patients with congenital deformity or pathology, systemic disease and ossified suture were excluded.

Records taken

All the necessary records were taken prior to the initiation of treatment, including case history, photographs, models, radiographs and bite registration.


The separators were placed before the fabrication of bands on 1 st premolars and 1 st molars in the upper arch. After separation, band pinching was done and an alginate impression was taken with the bands in place. The bands were removed carefully and repositioned in the impression. The impression was poured in the dental stone (Type 2) and the working model was obtained. A specially designed screw was fabricated, the details of which are as follows.

A Jack screw [Figure 1] of 14 mm length was embedded in dental plaster, with only the four corners of the screw (which move away from each other when the screw is turned) exposed [Figure 2]. 18-gauge (0.044″) stainless steel (SS) round wires of 5 cm length were hydro-soldered on the four corners of the Jack screw [Figure 3]. Acrylic capping was done on either side of the screw to prevent sliding of the guiding rods to one side of the screw [Figure 4].{Figure 1}{Figure 2}{Figure 3}{Figure 4}

Now, this screw is ready for adaptation on the palate. The four arms of the appliance were soldered to the bands as done in Hyrax, ensuring that sufficient space existed between the screw and the palatal mucosa.

Then, the appliance was cemented onto the 1 st premolars and 1 st molars in the patient's mouth [Figure 5].{Figure 5}

At the time of cementation of the appliance, verbal instructions were given to the parent and patient on the maintenance and activation of the appliance. It was cautioned that a string should be attached to the activation key and to the wrist of the person activating the appliance to prevent accidental swallowing of the key. [6]

Timms expansion schedule was followed in all the six cases. It included two turns immediately after insertion, followed by one turn (90°) in the morning and evening for 5 days and later one turn per day till the desired expansion was achieved.

After that, acrylic was placed to prevent unscrewing. This appliance was maintained as a retention appliance for a period of 3 months.

Post-expansion records were taken including photographs, impressions and radiographs.

The arch width measurement was estimated as shown in [Figure 6].{Figure 6}

The data were entered in Microsoft excel 2007. Data were compiled and analyzed by using SPSS version 17. Paired t-test was used to compare the pre-and post-treatment results. The level of significance was set at P<0.05.


Six patients were selected for maxillary expansion done by using the newly designed eRME appliance as an alternative to the costly Hyrax appliance.

[Figure 7] shows pre-and post-treatment intraoral views.{Figure 7}

The following results can be obtained from [Table 1]: Inter-canine width pre-treatment was 31.2 ± 2.56 mm and post-treatment was 35.6 ± 2.1 mm, showing gain in width of 4.4 ± 0.70 mm; the inter-premolar width pre-treatment was 25.4 ± 0.86 mm and post-treatment was 32.2 ± 0.86 mm, showing gain in width of 6.8 ± 1.48 mm; and the inter-molar width pre-treatment was 34.4 ± 0.72 mm and post-treatment was 43.8 ± 0.67 mm, showing gain in width of 9.4 ± 1.13 mm, which was found to statistically highly significant (P<0.001).{Table 1}

Effects of eRME

Maxillary skeletal effect-Clinically and radiographically (post-treatment occlusal X-ray), opening of mid-palatal suture was seen. It is fan shaped or triangular, with the apex directed posteriorly. Post-treatment lateral cephalogram showed downward displacement of maxilla.

Effects on maxillary anterior teeth-Clinically, appearance of midline spacing was seen. It is the most reliable evidence of maxillary separation. The amount of incisor separation is half of the amount of opening of the screw. By 2-3 months, midline spacing closes because of the trans-septal fiber traction.

Effects on maxillary posterior teeth-Sufficient molar expansion which led to the correction of the crossbite was seen. Some amount of buccal tipping was seen clinically. The upper molars rotated mesio-palatally, which can be corrected during the later stages of the treatment.

Effect on mandible-Downward and backward rotation and an increase in the mandibular plane angle was seen cephalometrically.

Effects of RME on nasal cavity-Increase in inter-nasal space was seen due to shallowing of the deep palate.


RME is an accepted procedure to relieve deficiencies in arch perimeter and to correct crossbite. During the past 20 years, with the increasing emphasis on non-extraction therapy, the procedure has gained in popularity because of the relief of crowding it provides. RME compensates for arch perimeter deficiencies through transverse expansion of the alveolar and dental arches. [16]

Various reports [17],[18],[19],[20],[21] have documented the skeletal as well as the dental changes that occur with rapid expansion of the maxilla. However, the magnitude of change in arch perimeter with transverse expansion of the dental arch has not been evaluated. Determination of a simple method for projecting increases in arch perimeter would be beneficial in planning orthodontic treatment.

RME treatment is able to induce significantly more favorable skeletal changes in the transverse plane when it is initiated before the pubertal peak in skeletal growth. This clinical finding agrees with histological data previously noted by Melsen, [22] which demonstrated a higher level of response to mechanical stimuli in the mid-palatal suture in preadolescent patients due to a lesser degree of interdigitation between the two halves of the maxilla. Wertz and Dreskin and Chung and Font [23],[24] also noted greater and more stable orthopedic changes in patients under the age of 12 years.

The study results showed an average expansion in canine, premolar and molar regions of 4.4 ± 0.70 mm, 6.8 ± 1.48 mm and 9.4 ± 1.13 mm, respectively, having significant difference pre-and post-treatment. Thus, it shows that maxillary expansion is efficiently possible with the application of this newly, economically designed RME appliance.

Unlike Hyrax, no wire component was given in the 2 nd premolar region. In spite of this, the 2 nd premolar moved along with 1 st premolar and 1 st molar. This again confirms that the expansion was skeletal.

The increment of arch width added by opening the mid-palatal suture is to be assured through the repair of the defect by new bone.

Here, the main advantages of comparing eRME with Hyrax are the cost factor and its simplicity to adapt because of its thinner gauge wire (18 gauge or 0.044″) which is sufficient to give skeletal expansion.


RME has tested the deep waters of time to be completely trusted and accepted as a respected treatment modality in the field of Orthodontics. Hence, we can conclude that eRME, which is an economical substitute for HYRAX, will find its place as an important tool in the armamentarium of an orthodontist for skeletal maxillary expansion.


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