Effects of Rapid Maxillary Expansion on Upper Airway; A 3 Dimensional Cephalometric Analysis

EFFECTS OF RAPID MAXILLARY EXPANSION ON UPPER AIRWAY; A 3 DIMENSIONAL CEPHALOMETRIC ANALYSIS Yoon H. Chang D.D.S. Marquette University, 2011 The purpose of this study was to use cone-beam computed tomography (CBCT) to assess changes in the volume and cross sectional areas of the upper airway in children with maxillary constriction treated by rapid maxillary expansion (RME). The study group consisted of 5 males and 9 females with mean age of 12.93 years with posterior cross bite and constricted maxilla who were treated with hyrax expander. Pre and post RME CBCT scans were analyzed with 3D Dolphin 11.0 software to measure the retropalatal (RP) and retroglossal (RG) airway changes. The transverse width changes were evaluated from the maxillary inter 1 molar and inter 1 pre molar mid lingual alveolar plate points. Pre and post RME scans were compared with paired t test and Pearson correlation test was done on data reaching significance. Only the cross sectional airway measured at posterior nasal spine (PNS) to Basion (Ba) level showed a statistically significant increase (P=0.0004). The inter-molar and inter-premolar mid lingual alveolar plate distances increased equally by 4.76 mm and were statistically significant (P< 0.0001). The percentage increase at the 1 premolar level was significantly larger than at the 1 molar level (P= 0.035). PNS-Ba cross sectional area increase was highly correlated with the maxillary 1 molar mid lingual inter alveolar plate width (p=0.0013). In conclusion, RME produced a numerically equal amount of expansion between the mid inter-lingual plates of maxillary 1 molars and 1 premolars. However, when the percentage change was calculated, a greater opening was observed at the 1 premolar level suggesting a triangular shape of opening. In regard to the upper airway, a moderate increase of the cross sectional area adjacent to the hard palate was found and this increase was deemed to be highly dependent on the expansion between the maxillary 1 molars. Further studies with a larger sample size and incorporating breathing evaluations are needed to estimate the real impact of the RME on the airway.