Objective: The purpose of this study was to evaluate the dental and skeletal changes in the maxillary bone morphology, produced by two-arm rapid palatal expansion appliances.
Patients and methods: The study included 22 girls with an average age of 11.9 years treated with RPE appliances at the Department of Pedodontics and Orthodontics, Faculty of Dentistry, Timisoara, Romania. We evaluated the changes on study casts, using an optical 3D scanner--Activity 101 (SmartOptics) and also on radiographs. The level of statistical significance was set by comparing the changes between pre and post treatment values. We also used the Pearson's correlation coefficient (r) to measure the strength of the association between the recorded measurements. The correlations were significant at p<0.05.
Results: Significant changes were found in intermolar width change, interpremolar width change, molar tipping and alveolar tipping. Less significant changes were found in molar rotation and palatal depth change. After rapid maxillary expansion, five of the 21 correlations were found to be statistically significant. Positive medium correlations were found between intermolar width change and alveolar tipping and between interpremolar width change and alveolar tipping. A negative medium correlation was found between palatal depth change and alveolar tipping. Weak, but statistically significant correlations were found between intermolar width change and interpremolar width change and between intermolar width change and palatal depth change. No statistically significant correlation was found between the other variables.
Conclusions: This type of maxillary expander is capable of expanding the maxillary dentition and alveolar process, opening the midpalatal suture and changing the maxillary bone morphology. The most remarkable changes occurred in the transverse plane. Future research is required to evaluate a larger group of patients.