Dentoskeletal changes and their correlations after micro-implant-assisted palatal expansion (MARPE) in adults with advanced midpalatal suture ossification

OBJECTIVES To evaluate and correlate the dentoskeletal changes of adult patients after miniscrew-assisted rapid palatal expander (MARPE) in the two final stages of midpalatal suture ossification. MATERIALS AND METHODS This interventional pre-post clinical study consisted of 20 adults (24.9±1.8 years), with transverse maxillary atresia, divided into two subgroups (n=10) based on the ossification degree of the midpalatal suture: stage D, fusion completed in the palatine bone; and stage E, fusion anteriorly in the maxilla. Cone beam computed tomography (CBCT) in the pre- (T0) and post-treatment (T1) time intervals were used to evaluate the anterior and posterior sutural opening, activation of the expander screw, vestibular-lingual inclinations, and widths of first premolars and first molars. Maxillary interincisor diastema was measured on patients' plaster models in the same timepoints. The Wilcoxon-Mann-Whitney test, generalized linear models (GLM), and chi-square (χ2) test were employed. RESULTS All variables significantly increased after MARPE therapy regardless of the ossification degree (P<0.05). Patients with stage D suture presented wider interincisal diastema and maxillary suture opening (on both regions, anterior and posterior) when compared with patients with stage E (P<0.05). Maxillary interincisor diastema was positively associated with anterior and posterior suture opening for all subjects (P<0.05). MARPE therapy was unsuccessful in six patients, mostly presented by individuals with E maturation stage of the midpalatal suture. CONCLUSIONS After MARPE, a significant correction in the transverse defect of the maxillary basal bone was achieved for adults in the last two midpalatal suture maturation stages. CLINICAL RELEVANCE Adult patients in stage D of maxillary suture ossification are more susceptible to dentoskeletal changes following MARPE therapy as compared to patients with stage E.