Dentofacial changes from fan-type rapid maxillary expansion vs traditional rapid maxillary expansion in early mixed dentition

Abstract

ABSTRACT Objective: To test the null hypothesis that there is no difference between the effects of fan-type rapid (FRME) and rapid maxillary expansion (RME) used with an acrylic bonded expansion appliance on dentofacial structures in early occlusal stages. Materials and Methods: This was a prospective clinical trial. The FRME group had an anterior constricted maxillary width with a normal intermolar width, and the RME group had bilateral constricted maxillary width. The FRME group consisted of 20 patients (mean age, 8.96 ± 1.19 years), and the RME group consisted of 22 patients (mean age, 8.69 ± 0.66 years). Lateral and frontal cephalometric radiographs and dental casts were taken before and after expansion and 3 months after completing treatment for each patient. The data were compared using repeated-measures analysis of variance. The paired-samples t-test was used to evaluate treatment and retention effects, and the independent samples t-test was used to consider the differences between the two groups. Results: The maxilla moved downward and forward in both groups. The nasal cavity and maxillary width were expanded more in the RME group, and there were only a few relapses in this group during the retention period. There was significant labial tipping of the upper incisors in the FRME expansion group. The expansion of intercanine width was similar in both groups, but the expansion of intermolar width was significantly greater in the RME group. Conclusion: The null hypothesis was rejected. There was a difference between the effects of FRME and RME used with an acrylic bonded expansion appliance on dentofacial structures in the early occlusal stages.