Three-dimensional Morphological Evaluation Of Maxillary Complex And Upper Airway And Computational Fluid Dynamics Simulation Of Upper Airway Response To Maxillary Skeletal Expander Treatment In Adults With Maxillary Transverse Deficiency

Objective:The purpose of this study was to investigate the morphological changes of maxillary complex and upper airway and computational fluid dynamics changes of upper airway using three-dimensional reconstruction,model registration and computational fluid dynamics simulation in maxillary transverse deficiency adult patients who treated by maxillary skeletal expander,in order to provide theoretical basis for clinical treatment.Materials and Methods:From our clinic archives,we selected 12 patients aged from 18 to 29 years with maxillary transverse deficiency(2 males and 10 females).All of those patients were treated by maxillary skeletal expander for approximately 3 weeks(average 19.50±3.73 days).Italian New Tom 5G CBCT was taken before expansion and no more than 1 week after completion of expansion.All of the data were collected and stored in DICOM format.The 3D model reconstruction and registration and CBCT image measurements were completed by Mimics 19.0 software and Dolphin Imaging 11.8 Premium software,respectively.Afterwards,the upper airway flow field characteristic were simulated by Ansys 16.0 software.And all of the results were analyzed by paired r-test in SPSS 17.0 software.Results:1.After the maxillary skeletal expander opened 4.91 ± 1.06mm in average,the increase of midpalatal suture in canine level and first molar level was 3.08±1.48mm and 2.62±1.06mm,respectiveIy.The distance between maxillary canines widened 2.03±1.12mm and the distance between maxillary first molars widened 4.28±1.56mm,which showed significant statistical differences(P<0.01).Comparing the width change of maxillary first molar and screw of the appliance,there is no statistical differences(P>0.05).However,the width change of midpalatal suture of molar level and screw of the appliance showed significant statistical differences(P<0.01).The lateral wall of nasal cavity widened 1.79±1.42mm,upper inter-zygomatic distance increased 1.40±0.70mm and lower inter-zygomatic distance increased 3.54± 1.44mm,which showed significant statistical differences(P<0.01).The minimum area of nasal cavity increased 47.12±46.54mm2 which showed significant statistical differences(P<0.01)and the minimum area of nasopharynx increased 47.22±58.10 mm2 which showed statistical differences(P<0.05).The volume of nasal cavity increased 439.98mm3 which showed significant statistical differences(P<0.01).2.Computational fluid dynamics simulation of the upper airway showed that,the pressure drop of nasal cavity decreased 8.26 ±6.20 Pa and the maximum velocity of flow decreased 1.19±0.73m/s after MSE treatment,which showed significant statistical differences(P<0.01).The drop pressure of pharynx decreased 2.95 ±3.27Pa which showed statistical differences(P<0.05)and the maximum velocity of pharynx decreased 0.46± 1.33m/s which showed significant statistical differences(P<0.01).Conclusions:1.Midpalatal suture opened after MSE treatment in maxillary transverse deficiency adult patients.The morphology of maxillary complex width(especially at zygomatic bone and nasal bone)and nasal volume significantly increased.2.CFD evaluation of upper airway indicated an evident resistance decrease at nasal airway area after MSE treatment in maxillary transverse deficiency adult patients.The resistance of upper airway decreased.