Skeletal and dental changes after microimplant-assisted rapid palatal expansion (MARPE)–a Cephalometric and Cone-Beam Computed Tomography (CBCT) study

Abstract

Purpose: The maxillary transverse discrepancy is common in orthodontic practice. Rapid palatal expansion has traditionally been used before puberty, but the skeletal effect is limited. Recently, micro-implant-assisted rapid palatal expansion (MARPE) has been proven to be effective in adolescents and adults. The purpose of this study is to assess the skeletal and dental 3-dimensional outcomes after MARPE. Materials and methods: Nineteen subjects who presented with a maxillary transverse discrepancy and received MARPE treatment were included in this study. Cephalometric radiographs and Cone-Beam Computed Tomography (CBCT) images were obtained and analysed at the initial (T1) and the end of the expansion (T2). The Wilcoxon signed-rank test was used to evaluate the differences between the two time points. Results: The results demonstrated anteroposterior correction. The SNA, ANB, FH-NA, N-A-Pog, A-Na perpendicular (mm) and U1-Nasion perpendicular (mm) all increased from T1 to T2, which explained the maxillary advancement after MARPE. The SN-MP, PP-MP and SNB changes indicated a mandible backward rotation followed expansion. In the CBCT analysis, the average expansion amount was 5.5 mm, of which 71.1% was due to a skeletal effect. In addition, the expansion pattern was almost parallel with a ratio of 83.2% from PNS to ANS. Conclusions: MARPE treatment can provide successful transverse correction with near parallel expansion of the maxilla in the coronal and axial planes. Maxillary advancement and a mandibular backward rotation associated with MARPE can provide positive correction in the sagittal plane. As dentoalveolar tipping was limited, the expansion result was mainly skeletal.