Effect of rapid maxillary expansion on skeletal, dental, and nasal structures: a postero-anterior cephalometric study

The purpose of this study was to compare the transverse dimensions of skele tal, dental, and nasal structures of a group of patients with maxillary nar rowness before and after rapid maxillary expansion (RME) with an untreated control group using postero-anterior (PA) cephalometric radiographs. The ma terial consisted of PA cephalograms of 25 children with a posterior crossbi te (mean age 13 years 4 months), and 25 age- and sex-matched controls (mean age 13 years 11 months). Both groups consisted of 20 females and five male s. Thirty-four reference points were digitized using the Dentofacial Planne r(R) software program. The 17 variables studied consisted of six skeletal, four dental, and seven intra-nasal linear measurements. Student's t-tests w ere used to compare the differences between the groups, and the effect of R ME on skeletal, dental, and nasal structures. RME produced small, but statistically significant changes in maxillary widt h, upper and lower molar widths, the width between tapper central incisor a pices, and intra-nasal width. When compared with previous studies, the chan ges observed were similar for patients of a similar age group, but less tha n reported for a younger population. There is some evidence that the patter n of expansion produced by RME will vary depending on the age and maturity of the subject.