2.2. Clinical Procedure

Ten patients (4 male and 6 female) were submitted to palatine suture expansion by RME procedures through McNamara appliance, which is a tooth-supported orthodontic appliance that consists of two acrylic parts attached in the posterior tooth and connected by an expansion screw in the midpalatal region (Figure 1). The inclusion criteria were patients between 9–17 years of age and in good health, who presented signs and symptoms of maxillary skeletal transverse deficiency and A or B stage midpalatal suture maturation according to Angilieri’s classification [24]. Patients who were not within the selected age range, presented a different bone maturation stage (C, D or E), presented systemic conditions, craniofacial syndromes, malformations or had a different diagnosis or treatment plan were excluded. Afterwards, the rapid maxillary expansion procedure through McNamara was made by taking oral impressions with two-phase silicone (Aquasil, Dentsply, Erlangen, Germany). The expansion device was 13 mm long with 1.5 mm thick arms and 0.8 mm full turn (Leone, Florence, Italy) and glass-ionomer cement was used to adhere on the upper molars and premolars. The expansion protocol (Figure 1) was 1/4 turn per day for 15 days (0.4 mm per day), which was the active period of disjunction [26]. The appliance was subsequently kept for up to 9 months of passive retention to avoid relapses.

(A) Preoperative occlusal and (B) frontal view, and (C) postoperative occlusal and (D) frontal view after RME treatment with McNamara appliance.