Influence of rapid maxillary expansion in the stability of anterior open bite treatment

Objectives This study aimed to compare the stability of anterior open bite (AOB) in patients treated with and without rapid maxillary expansion (RME) before fixed palatal crib (PC) therapy in the mixed dentition. Material and methods Expansion/palatal crib group (EPC) was comprised of 25 patients (10 male, 15 female, mean initial age of 7.8 years) with AOB treated with RME before PC therapy. Palatal crib group (PC) included 25 patients with AOB (10 male, 15 female, mean initial age of 8.0 years) treated only with PC therapy. Lateral cephalograms were analyzed at pre-treatment (T0), after PC therapy (T1), and 3 years after PC removal (T2) in both groups. AOB relapse was considered when a negative overbite was observed at T2. Intergroup comparisons of interphase changes were performed using t and Mann-Whitney tests (p < 0.05). Results Treatment and post-treatment alterations showed similar changes in both groups for all cephalometric variables. Overall changes from T0 to T2 were similar between the groups except for the maxillary incisors that tipped lingually in PC group (1.PP = - 3.37 degrees) and labially in EPC group (1.PP = 1.76 degrees). The frequency of AOB relapse was 8% and 4% in the EPC and PC groups, respectively. Treatment time in the EPC group (9.7 months) was shorter (p = 0.024) when compared to the PC group (11.0 months). Conclusions In the mixed dentition, stability of AOB treated with RME before fixed PC therapy was similar to PC therapy alone. However, treatment time with fixed PC was slightly shorter in the group treated with RME.