Comparison of Dentofacial and Periodontal Effects of Rapid and Semi-rapid Maxillary Expansion

Objective: The purpose of this study was to compare the skeletal, dentoalveolar and periodontal effects that occurred after rapid maxillary expansion (RME) and semirapid maxillary expansion (SRME) with an acrylic splint bonded expansion appliance and also to compare the degree of root resorption in the supporting teeth during expansion. Materials and Methods: The sample of the study included 19 patients having maxillary constriction requiring bilateral upper premolar extraction. The semi-rapid group consisted of 10 patients and the rapid group consisted of 9 patients. Lateral and posteroanterior (PA) cephalometric radiographs were taken at the beginning of the treatment, at the end of expansion and after 3 months of retention period. Eleven patients underwent low-dose computed tomography (CT) at the beginning of treatment and at the end of retention period, after giving informed consent. The evaluation of root resorption was made using a scanning electron microscope from the extracted teeth. Results: Both lateral and PA radiographs showed similar changes between the groups. Posterior nasal cavity width, palatal maxillary width, the distance between palatinal roots and the distance between incisor roots showed significant increase in the CT measurements. Buccal bone thickness decreased and palatal bone thickness increased in all molar and premolar teeth examined. Root resorption was seen in both groups, but no significant differences were observed between the groups. Conclusion: Some differences were seen in short-time effects between SRME and RME but these differences were temporary and disappeared at the end of the retention period. The qualitative evaluation of the roots showed that the location and degree of the root resorption were similar between the groups