【摘要】 目的分析不同程度下颌第二前磨牙冠根折行牙冠延长术并桩冠修复后的牙周膜应力,探讨下颌第二前磨牙牙冠延长术的适应症。方法通过螺旋CT扫描获得原始二维图像数据,将获得的二维图像数据输入Mimics软件建立下颌第二前磨牙冠根折行牙冠延长术并桩冠修复后的三维模型,将模型的三维图像数据导入Ansys软件,在Ansys中对已经建立好的模型的牙周膜进行应力分析。结果当冠延长1 mm和2 mm时,牙周膜应力值逐渐增加,当延长3 mm、4 mm和5 mm时应力变化波动较小,当冠延长5 mm时,各应力值均未超过耐受阈值。结论当冠延长5 mm时牙周膜所受应力仍在安全范围内。牙颈部2 mm范围内牙周膜对牙周组织的支持力影响重大,因此在临床工作中应尽量保存牙颈部范围内的牙周组织的健康。更多还原

【Abstract】 Objective The study serves to discuss the indication of crown lengthening surgery(CLS) by investigating stress distribution on periodontal ligament of the fracture mandibular second premolar after restoration at different degrees of crown-root fracture having done CLS.Methods Two-dimensional images of the mandibular second premolar acquired by thin-layer CT were transferred into mimics software to obtain the models of the fracture mandibular second premolar after restoration at different degrees of crown-root fracture having done CLS.The Ansys software was adopted to analyze stress distribution of periodontal ligament in the models.Results When crown was lengthened from 1 to 2 mm,the values of stress on periodontal ligament increased gradually.When crown was lengthened from 3 to 5 mm,the values of stress on periodontal ligament changed a little.The values of stress on periodontal ligament were not beyond the tolerance threshold when crown was lengthened no more than 5 mm.Conclusions The values of stress on periodontal ligament are within the range of the tolerance threshold when crown is lengthened no more than 5 mm.The 2 mm periodontal ligament wrapping the dental cervix poses a significant effect on the support capacity of the periodontal tissue,and it should be conserved clinically.更多还原