不同腭部形态MSE放置不同位置对颅面复合体和扩弓效果的影响

Effects of different positions of MSE placement in different palatal morphologies on craniofacial complex and arch expansion effect

目的利用三维有限元分析上颌骨性扩弓器(MSE)放置不同位置对颅面复合体和扩弓效果的影响。方法利用锥形束CT(CBCT)及建模软件构建微种植钉支持式的三维有限元模型,模型构造包含MSE、牙列及颅骨。将不同腭部形态的颅上颌复合体模型分为腭盖正常组和腭盖高拱组,在这两种腭部形态下将MSE分别放置于第二前磨牙与第一磨牙间、第一磨牙间、第一与第二磨牙间,共分为6个模型(模型一,模型二,模型三,模型四,模型五,模型六)。每组将螺旋扩弓器分别施加0.25 mm横向位移,比较颅上颌复合体及第一磨牙的应力分布及位移趋势。结果腭盖正常组颅上颌复合体等效应力为模型三>模型一>模型二,腭盖高拱组颅上颌复合体等效应力为模型四>模型五>模型六。各骨缝等效应力变化呈线性关系,其中颧颞缝、翼腭缝、额颌缝、颧额缝等效应力较高。随着扩弓器位置后移,翼腭缝、额颌缝、颧额缝应力呈递增趋势。腭中缝x轴位移中,腭盖正常组:模型二>模型三>模型一;腭盖高拱组:模型五>模型六>模型四;扩弓器相同位置腭盖高拱组腭中缝x轴位移均小于腭盖正常组。腭盖高拱组与腭盖正常组的腭中缝宽度相比差异不明显。腭盖正常组与腭盖高拱组的上颌第一磨牙三维方向位移程度相比差异不显著。结论MSE扩弓后颅上颌复合体应力分布广泛,腭盖正常组在第一磨牙间应力最小,腭盖高拱组在第一与第二磨牙间应力最小;MSE对各骨缝均有应力分布,其中翼腭缝应力分布较高;两种腭部形态下MSE放置在第一磨牙间腭中缝扩弓效果最好;腭中缝呈前大后小的楔形打开,MSE放置位置越靠后越有利于腭中缝的平行扩展;随着上颌扩弓器位置后移,第一磨牙颊倾越明显;腭部形态对MSE扩弓效果影响较小。

Objective To investigate the effect of different positions of maxillary bone expander(MSE)place-ment in different palatal morphologies on craniofacial complex and arch expansion effect by 3D finite element analysis.Methods Cone beam CT(CBCT)and modeling software were used to construct a 3D finite element model supported by microimplant nails,including MSE,dentition,and skull.The cranial maxillary complex models with different palatal morphologies were divided into the normal palatal operculum group and the palatal operculum high arch group,and the MSE was placed between the second premolars and the first molar,the first molar,and the first and second molars,re-spectively,which were divided into 6 groups(model 1,model 2,model 3,model 4,model 5,and model 6).Each group applied a 0.25 mm lateral displacement to the spiral arch expander to compare the stress distribution and displacement trend of the cranial maxillary complex and the first molar.Results The equivalent force of the cranial maxillary com-plex in the normal palatal operculum group was reduced successively in model 3,model 1,model 2,and the equivalent force of the cranial maxillary complex in the palatal operculum high arch group was reduced successively in model 4,model 5,model 6.The equivalent force of each bone suture showed a linear relationship,among which the zygotemporal suture,pterygopalatine suture,frontal suture,and zygofrontal suture have higher effect force.As the position of the ex-pander moved back,the stress of pterygpalatine suture,frontal suture,and zygomatic frontal suture increased successive-ly.The X-axis displacement of the middle palate suture in the normal palatal operculum group decreased successively in model 2,model 3,model 1,and that in palatal operculum high arch group decreased successively in model 5>model 6>model 4.The X-axis displacement of the middle palate suture at the same position of the arch expander in the palatal operculum high arch group was smaller than that in the normal palatal operculum group.The palatal suture width was not significantly different between the two groups.There was no significant difference in the three-dimensional displace-ment of maxillary first molars between the two groups.Conclusion The stress distribution of the cranial maxillary complex after MSE arch expansion is extensive,and the stress is the lowest between the first molars in the normal pala-tal operculum group and between the first and second molars in the palatal operculum high arch group.MSE has stress distribution for each bone suture,among which the stress distribution of pterygopalatine suture is high.In the two palate morphologies,MSE is best placed in the palate between the first molars to expand the arch.The middle palate suture opens in a wedge shape with a large anterior and small posterior position,and the further back the MSE is placed,the more conducive to the parallel expansion of the middle palate suture.As the position of the maxillary arch expander shifts back,the first molar's cheek tilt becomes more pronounced.Palatal morphology has little effect on MSE arch ex-pansion.