伴偏斜对下颌前突患者颞下颌关节应力分布的影响

The Influence of Facial Asymmetry on Stress Distributions in Temporomandibular Joints for Patients with Mandibular Prognathism

目的探究伴偏斜对下颌前突患者颞下颌关节(temporomandibular joint,TMJ)应力分布的影响。方法在Mimics中建立4名下颌前突伴偏斜患者和4名下颌前突不伴偏斜患者的三维颌面部模型,在ABAQUS中赋予模型偏侧咬合(单侧磨牙咀嚼)的肌肉力与边界条件,分析偏侧咬合工况下患者TMJ的最大和最小主应力。结果偏侧咬合工况下,伴偏斜患者髁突的平均最大应力显著大于不伴偏斜患者(P<0.05),伴偏斜会使髁突处应力增加2~3倍,关节窝应力增加5~7倍,且伴偏斜患者中颞下颌关节紊乱综合征(temporomandibular disorder,TMD)患者同侧TMJ处的应力高于无TMD患者。结论伴偏斜会增大患者髁突和关节窝的应力,TMD会引起伴偏斜患者同侧TMJ的高应力。建议根据偏斜与否考虑下颌前突的治疗。

Objective To explore the effects of facial asymmetry on stress distributions in temporomandibular joints(TMJs)for patients with mandibular prognathism.Methods Eight 3 D maxillofacial models were established in MIMICS based on cone-beam CT of 4 mandibular prognathism patients with asymmetry and 4 mandibular prognathism patients without asymmetry.Muscle forces and boundary conditions corresponding to the unilateral occlusion(unilateral molar chewing)were applied on the models in ABAQUS.The maximum and the minimum principal stresses of TMJ were chosen for analysis.Results There were significant differences in the maximum and minimum principal stresses at the condyles between the mandibular prognathism patients with and without facial asymmetry under unilateral occlusions(P<0.05).Compared with patients without facial asymmetry,the stresses on the condyle in patients with asymmetry increased by 2-3 times,and the stresses on articular fossa increased by 5-7 times.Among the mandibular prognathism patients with asymmetry,the stresses of the ipsilateral TMJ in patients with temporomandibular disorder(TMD)were significantly higher than those in patients without TMD.Conclusions Facial asymmetry increased the stresses of the articular fossa and condyle in patients with mandibular prognathism.TMD would cause greater stresses in ipsilateral TMJ of the mandibular prognathism patient with asymmetry.Therefore,different treatment strategies should be considered for mandibular prognathism with facial asymmetry.