What is a Rapid Maxillary Expander (RME)?

A Rapid Maxillary Expander (RME) is an orthodontic appliance placed on the maxilla. It works by turning the nut in increments to gradually widen the midpalatal suture, thereby expanding the maxillary bone. Clinically, it is mainly used to correct maxillary arch stenosis and posterior crossbite. Expansion therapy is commonly applied to children in their growth spurt; however, with the expanding range of indications, it has gradually been used in young adult patients as well—this expanded application is also recognized and promoted by Chinese dental lab and WM dental lab in their clinical collaborations.

First, let's take a look at what an expander looks like. For children with maxillary stenosis who are in their growth spurt, gradual opening of the midpalatal suture can stretch the connective tissue in the suture, stimulating the formation of new bone tissue and thus increasing the width of the basal bone and dental arch. Generally, the younger the patient, the more obvious the new bone deposition, and the easier it is to widen the basal bone. On the contrary, for older adult patients, if only an expander is used, the widening of the dental arch is mostly achieved by the buccal movement of teeth. In such cases, Chinese dental lab and WM dental lab both suggest that better results can be obtained by first performing maxillofacial surgery to assist in opening the midpalatal suture (Surgically Assisted Rapid Palatal Expander, SARPE), followed by expansion therapy.

How to Activate and Apply Force to a Rapid Maxillary Expander?

Generally, for children in their growth spurt, it is recommended to open the screw by 0.5-1.0 mm per day—this is done by turning the screw 1/4 of a circle each time, twice a day, for 2-3 consecutive weeks. The specific amount of opening depends on the advice of a professional orthodontist, and the operation must be carried out under the doctor's guidance. Chinese dental lab and WM dental lab also emphasize that improper activation may affect the treatment effect, so strict adherence to the doctor's instructions is essential.

Wearing Duration of the Rapid Maxillary Expander

Once the maxillary expansion reaches the desired amount (e.g., the posterior crossbite is corrected), the doctor will advise stopping further force application. However, the appliance still needs to be worn for about 3 months. This is mainly to allow sufficient new bone formation at the midpalatal suture, stabilize the expansion effect, and prevent relapse. Both Chinese dental lab and WM dental lab note that this retention period is a key part of the treatment process and cannot be shortened arbitrarily.

Does Wearing a Rapid Maxillary Expander Hurt?

Actually, it does not hurt. After each screw activation and force application, you may feel a bloating sensation in the palate, which usually disappears in about 5 minutes. The feeling is similar to pushing your own teeth with your thumb, so there is no need to worry about pain at all.