The Three-dimensional Finite Element Analysis Of An Obstructive Sleep Apnea Hypopnea Syndrome Patient’s Hyoid Bone Position Changement With Titrated Mandibular Advancement

Obstructive sleep apnea hypopnea syndrome（OSAHS) is characterized byrepetitive sleep apnea, oxygen saturation decreased due to upper airway collapse.There are many studies about position changes of hyoid in OSAHS patient,butwhether if there is relevence between position change of hyoid and mandibularadvancement,and even there is regulation in position change of hyoid are still inargue.Most of the past studies are two-dimensional,three-dimensional methodssuch as computerized tomography(CT) are still and interval.These methods cananalyze one movement position of hyoid while Three-dimensional Finite Elementanalyse can analysis the whole process of position change of hyoid withmandibular advancement escaping from extra radiation and disturbance.Three-dimensional finite element method is the most advanced and effectivemethod of biomechanical analysis in medicine. This study obtained the accurateDicom format of the image information of OSAHS patient’s upper airway by usingspiral CT scan and establish an accurate, flexible simulation OSAHS patient’supper airway model by using Mimics and Ansys software. Through loading ofmandibular advancement, position change of hyoid can be simulated, which laythe foundation for the OSAHS patient’s upper airway biomechanical analysis, aswell as provide a theoretical basis for Oral appliance optimal design for OSAHStherapy, while exploring a new way of thinking for future research of OSAHS. Objective Construct a three-dimensional finite element model of the Upperairway and adjacent structure of an Obstructive sleep apnea hypopnea syndromepatient and regulate protrusion of mandibular, the position changes of hyoid andits relationship with the mandibular protrusion can be observed and analysizedwhich providing theoretical basis for mechanism studies of treatment to OSAHSwith mandibular protraction.Methods DICOM format image information of an OSAHS patient’s upperairway obtained by thin—section CT scanning and digital image processing wereutilized to construct a three—dimensional finite element model by Mimics andAnsys software. And then titrated mandibular advancement, the changes and thelaw of palatopharyngeal part observed by biomechanics and morphologic.Results A case of OSAHS and the adjacent upper airway structure ofthree-dimensional finite element model is constructed which is formed by solid92tetrahedral unit of a10-node mesh. The model has cortical bone:562920elements,544929nodes;spongy bone:50141elements,84869nodes; muscle andupper airway:336789elements,303134nodes. After mandibular advancement,hyoid part of three-dimensional finite element of OSAHS change significantly.The main manifestations are: the hyoid move ahead and upward; the section ofpalatopharyngeal part which shape of oval reduce in transverse diameter whileincrease in sagittal diameter..Conclusion Establish accurate, flexible three-dimensional finite elementmodel of the upper airway and vicinity structure of an OSAHS patient with the useof spiral CT technology and Mimics software, Ansys software. The model hasgood geometric similarity and good flexibility.Through mandibular advancement,palatopharyngeal part on OSAHS loading analysis of finite element model, theeffective show the relationship between mandibular advancement and the hyoid, which confirming that the study is feasibility, providing a theoretical basis fortreatment of OSAHS with Mandibular advancement appliance and laying a goodfoundation for the following study of upper airway in OSAHS patients withbiomechanical analysis.