Transverse changes determined by rapid and slow maxillary expansion-a low-dose CT-based randomized controlled trial

Abstract

Objectives- To compare transverse skeletal changes produced by rapid (RME) and slow (SME) maxillary expansion using low-dose computed tomography. The null hypothesis was that SME and RME are equally effective in producing skeletal maxillary expansion in patients with posterior crossbite. Setting and Sample Population- This study was carried out at the Department of Oral Sciences, University of Naples Federico II, Italy. Twelve patients (seven males, five females, mean age±SD: 10.3±2.5years) were allocated to the SME group and 14 patients (six males, eight females, mean age±SD: 9.7±1.5years) to the RME group. Materials and Methods- All patients received a two-band palatal expander and were randomly allocated to either RME or SME. Low-dose computed tomography was used to identify skeletal and dental landmarks and to measure transverse maxillary changes with treatment. Results- A significant increase in skeletal transverse diameters was found in both SME and RME groups (anterior expansion=2.2±1.4mm, posterior expansion=2.2±0.9mm, pterygoid expansion=0.9±0.8 mm). No significant differences were found between groups at anterior (SME= 1.9±1.3mm; RME=2.5±1.5mm) or posterior (SME=1.9±1.0mm; RME=2.4±0.9mm) locations, while a statistically significant difference was measured at the pterygoid processes (SME=0.6±0.6mm; RME=1.2±0.9mm, p=0.04), which was not clinically relevant. Conclusion- Rapid maxillary expansion is not more effective than SME in expanding the maxilla in patients with posterior crossbite. © 2012 John Wiley & Sons A/S.