Facies Cranii And Upper Airway Changes After Rapid Maxillary Expansion And Maxillary Protraction On Skeletal Class â…¢ Malocclusion

Objective: This study was conducted to examine the effect of treatment with rapid maxillary expansion(RME)and maxillary protraction appliance on the development of the craniofacial structures and upper-airway dimensions in 20 subjects exhibiting a Skeletal Class III malocclusion with a retruded maxilla, and to evaluate the relationship between changes in the craniofacial morphology and upper-airway dimensions and to provide theoretical basis for clinical treatment.Methods: Twenty subjects( 9 males and 11 females mean age10.5y)from the Hebei Medical University Dental Hospital of orthodontics were diagnosed by cephalometric analysis as skeletal Class III malocclusions with maxillary retrognathism. All subjects with the treatment of rapid maxillary expansion for 15 days and maxillary protraction for 5.5 months. Cephalometric radiographs and posteroanterior(PA) were taken before treatment(T0), after RME (T1)and after maxillary protraction(T2).All the landmarks were taken by one person at one time and measured by Winceph8.06 software. The means and standard deviations of the changes in various measurements were obtained with SPSS 13.0 software.Results: After effective treatment, all the anterior crossbites were corrected. Cephalometric analysis showed that:1 After RME, the soft tissues and hard tissues have a litter changes.The items changes with statistically significant on Cephalometric radiographs: SNA,MP-FH,MP-SN,OJ have a statistically significant increases(P<0.05) and I1-I2 have a statistically significant diminished. The item changes with statistically significant on posteroanterior(PA): Mx-Mx',Zmd-Zmd',Umol-Umol'have a statistically significant increases(P<0.05). 2 After maxillary protraction the hard tissues changed a lot. The measurements changes with statistically significant on Cephalometric radiographs involve: SNA,ANB,NA-PA,MP-SN,NP-AB,MP-FH,U1-SN,OJ have statistically significant increases(P<0.05). SNB,OP-SN,PP-SN,L1-MP have statistically significant diminished. The anterior crossbites were corrected.3 The measurements of Air way and hyoid bone which have statistically significant changes involve UPW-PNS,SPP-SPPW,H-SN,H-FH,H-MP,H-Or,V-TH have a statistically significant increases. PAS,V-LPW have a statistically significant diminished. It means that the hyoid bone moved backwards and downward. The sagittal diameter of upper airway superior part increased and the inferior part diminished.Conclusion:1After RME, Significant increase of the maxillary transversal width and clockwise rotation of the mandible were observed. 2 After maxillary protraction significant increase in maxillary forward growth were observed. The anterior crossbites were corrected. And significant changes were observed at hyoid bone. After treatment, it moved backwards and downward.3 Significant changes were observed at upper airway. The superior part increased and the inferior part diminished. It may be caused by the move of maxillary and hyoid bone.