CAJ | 학술논문

目的探讨通用型面部软组织三维有限元模型的个性化转换方法,为正畸临床分析前牙内收对面部软组织形态的影响提供参考.方法以1名健康志愿者A的螺旋CT数据为基础,建立包括表面皮肤、脂肪、骨骼、牙齿及7对口周肌肉在内的通用型面部三维有限元模型.分别选取1名健康志愿者B和1例临床错验患者,利用两者锥形束CT重建数据与通用型模型的解剖性标志点坐标值,使用基于径向基函数的插值算法对通用型三维有限元模型进行个性化转换,将个性化转换后的三维有限元模型与锥形束CT重建数据重叠,进行个性化转换验证.选取2例具备完整治疗前后锥形束CT数据的临床错(拾)患者,将治疗前后锥形束CT三维重建数据重叠,获得前牙内收及前部牙槽嵴表面的改建量,作为边界条件代入治疗前个性化三维有限元模型计算,得到预测模型,将其与治疗后锥形束CT重建数据进行三维比较,调整并找出合理的赋值.结果个性化转换得到的三维有限元模型与锥形束CT重建数据的软、硬组织表面平均差值分别为0.47和0.75 mm,通过改进模型转换的方法,可使面部软组织区域的正负平均差值缩小至+0.29和-0.21 mm.对于预测模型,将皮肤、肌肉和脂肪的泊松比均设为0.45,弹性模量分别设为90.0、6.2和2.0 kPa时可获得最佳预测结果.结论利用锥形束CT数据,并使用径向基函数的插值算法,可实现通用型三维有限元模型的个性化转换,得到包含面部不同层次软组织的个性化三维有限元模型.
목적 탐토통용형면부연조직삼유유한원모형적개성화전환방법,위정기림상분석전아내수대면부연조직형태적영향제공삼고.방법 이1명건강지원자A적라선CT수거위기출,건립포괄표면피부、지방、골격、아치급7대구주기육재내적통용형면부삼유유한원모형.분별선취1명건강지원자B화1례림상착험환자,이용량자추형속CT중건수거여통용형모형적해부성표지점좌표치,사용기우경향기함수적삽치산법대통용형삼유유한원모형진행개성화전환,장개성화전환후적삼유유한원모형여추형속CT중건수거중첩,진행개성화전환험증.선취2례구비완정치료전후추형속CT수거적림상착(습)환자,장치료전후추형속CT삼유중건수거중첩,획득전아내수급전부아조척표면적개건량,작위변계조건대입치료전개성화삼유유한원모형계산,득도예측모형,장기여치료후추형속CT중건수거진행삼유비교,조정병조출합리적부치.결과 개성화전환득도적삼유유한원모형여추형속CT중건수거적연、경조직표면평균차치분별위0.47화0.75 mm,통과개진모형전환적방법,가사면부연조직구역적정부평균차치축소지+0.29화-0.21 mm.대우예측모형,장피부、기육화지방적박송비균설위0.45,탄성모량분별설위90.0、6.2화2.0 kPa시가획득최가예측결과.결론 이용추형속CT수거,병사용경향기함수적삽치산법,가실현통용형삼유유한원모형적개성화전환,득도포함면부불동층차연조직적개성화삼유유한원모형.
Objective To get individualized facial three-dimensional finite element (FE) model from transformation of a generic one to assist orthodontic analysis and prediction of treatment-related morphological change of facial soft tissue.Methods A generic three-dimensional FE model of craniofacial soft and hard tissue was constructed based on a volunteer's spiral CT data.Seven pairs of main peri-oral muscles were constructed based on a combination of CT image and anatomical method.Individualized model could be obtained through transformation of the generic model based on selection of corresponding anatomical landmarks and radial basis functions(RBF) method.Validation was analyzed through superimposition of the transformed model and cone-beam CT(CBCT) reconstruction data.Pre-and post-treatment CBCT data of two patients were collected,which were superimposed to gain the amount of anterior teeth retraction and anterior alveolar surface remodeling that could be used as boundary condition.Different values of Poisson ratio v and Young's modulus E were tested during simulation.Results Average deviation was 0.47 mm and 0.75 mm in the soft and hard tissue respectively.It could be decreased to a range of + 0.29 mm and -0.21 mm after a second transformation at the lip-mouth region.The best correspondence between simulation and post-treatment result was found with elastic properties of soft tissues defined as follows.Poisson ratio v for skin,muscle and fat being set as 0.45 while Young's modulus being set as 90.0 kPa,6.2 kPa and 2.0 kPa respectively.Conclusions Individualized three-dimensional facial FE model could be obtained through mathematical model transformation.With boundary condition defined according to treatment plan such FE model could be used to analyze the effect of orthodontic treatment on facial soft tissue.