A 23-year-old man visited with the chief complaint of malocclusion. He was diagnosed with transverse maxillary deficiency and posterior crossbite, which presented a skeletal class I pattern, anterior crowding, labioversion of the incisor teeth, and impaction of the mandibular right second molar by clinical and radiographic examination (Figure 1) The patient had no syndrome and no other medical conditions for transverse maxillary deficiency.
In this case, the patient had closed midpalatal suture, so possible treatment include SARPE and segmented osteotomy of the maxilla. SARPE and osteotomy were planned to correct the transverse compression and posterior crossbite.
Four tent screws (Tent screw, Neobiotech, Seoul, South Korea) were placed under local anesthesia prior to the osteotomy surgery, and an impression of the upper maxillary arch was taken for the appliance (Figure 2).
The tent screws had the following dimensions: diameter 2 mm, length 10 mm. Generally, tent screws are used for guided bone regeneration to maintain the space between the membrane and bone for bone formation to ease the fixing of membrane. These screws have a hole for the cover screw, and we used this hole for setting the appliance (Figure 3).
The patient underwent a bilateral osteotomy and splitting of the midpalatal suture according to the procedure described by Glassmann [9]. This procedure was performed under general anesthesia.
The rigid arms of the customized RPE appliance were designed to fit in the cover screw hole, which were made to be 1 mm in the actively expanded state in the laboratory. When the appliance was set in the upper arch, the activated screw was unwound to the inactivated state, placed to fit in the hole and activated to 1 mm again to retain the appliance. So, we could solve the problem if there were some errors on device, and the device could be fitted well on proper position (Figure 4).
We activated the appliance 2 times a day (1 activation = +0.25 mm) for 14 days, for a total of 7 mm. After the expansion was completed and the screw was immobilized, the appliance acted as a fixed retainer for a period of 6 months to allow the tissues to reorganize in their new positions. Orthodontic brackets were placed and orthodontic force was applied after activation was terminated (Figure 5).
Upper arch impressions were taken to include the occlusal surfaces of the teeth using rapid-setting alginate at the time of appliance fitting and after 2 weeks. Using digital calipers, the arch widths were measured on the resulting models between the maxillary first molars and the incisors, and a 2.27-mm increase in the intermolar width and a 3.25-mm increase in the interincisor width were observed after active expansion. This result remained stable after 6 months, 1 years, and 2 years. No significant differences was found. The patient didn’t show dental problem and anchorage loss. Also, the patient felt comfortable on the distraction procedure.