Long-term evaluation of rapid maxillary expansion and bite-block therapy in open bite growing subjects: A controlled clinical study.

Abstract

To evaluate the long-term effects of rapid maxillary expansion (RME) and posterior bite block (BB) in prepubertal subjects with dentoskeletal open bite. The treatment group (TG) comprised 16 subjects (14 girls, 2 boys) with dentoskeletal open bite with a mean age of 8.1 ± 1.1 years treated with RME and BB. Three consecutive lateral cephalograms were available before treatment (T1), at the end of the active treatment with the RME and BB (T2), and at a follow-up observation at least 4 years after the completion of treatment (T3). The TG was compared with a control group (CG) of 16 subjects (14 girls, 2 boys) matched for sex, age, and vertical skeletal pattern. An independent sample t-test was used to compare the T1 to T3, T1 to T2, and T2 to T3 cephalometric changes between the TG and the CG. In the long term, the TG showed a significantly greater increase in overbite (+1.8 mm), reduced extrusion of maxillary and mandibular molars (-3.3 mm), and, consequently, a significant decrease in facial divergence (-2.8°) when compared with untreated subjects. The RME and BB protocol led to successful and stable recovery of positive overbite in 100% of the patients considered. Correction of open bite was associated with reduced extrusion of maxillary and mandibular molars with a significant improvement in vertical skeletal relationships when compared with the CG.