摘要目的:通过有限元分析探讨直线通路微创开髓洞型对上颌第一前磨牙力学性能的影响。方法:收集2018年6月至2020年6月于四川大学华西口腔医院口腔颌面外科就诊患者因正畸或牙周病拔除的上颌第一前磨牙，从中选取牙体完整、根尖孔发育完成的双根管牙20颗，对其显微CT（micro-CT）数据进行三维重建，在三维模型中模拟传统开髓洞型、桁架开髓洞型与直线通路微创开髓洞型的开髓与根管治疗（每组样本量均为20个）。建模完成后进行有限元分析，记录纵向及斜向负载模式下各组模型的牙颈部von Mises等效应力峰值（VM）并观测各组模型的应力分布模式。结果:纵向负载模式下，3种开髓洞型牙颈部颊侧和腭侧VM分别为：桁架开髓洞型［（146.0±12.9）和（167.6±15.9）MPa］，直线通路微创开髓洞型［（142.6±13.7）和（168.1±17.4）MPa］，传统开髓洞型［（188.7±13.4）和（200.9±25.7）MPa］。与传统开髓洞型相比，桁架开髓洞型（ t=9.01， P<0.001； t=4.59， P<0.001）和直线通路微创开髓洞型（ t=9.64， P<0.001； t=3.76， P=0.004）均可有效降低根管治疗后上颌第一前磨牙颊侧和腭侧牙颈部VM，同时缓解应力在 面集中力加载区域、牙颈部及牙根的集中。在斜向负载模式下得到了相似的结果。在两种负载模式下，桁架开髓洞型与直线通路微创开髓洞型间颊腭侧牙颈部VM差异均无统计学意义（ P>0.05）。 结论:直线通路微创开髓洞型可以有效保护根管治疗后上颌第一前磨牙的力学性能，具有一定的临床可行性。

abstractsObjective:To investigate the effects of straight-line minimally invasive access cavity on the mechanical properties of endodontically treated maxillary first premolars using finite element analysis.Methods:Micro-CT data of twenty maxillary first premolars were collected for three-dimensional reconstruction. Three access cavities, including the conventional access cavity (ConvAC), the truss access cavity (TrussAC) and the straight-line minimally invasive access cavity (SMIAC), as well as the root canal treatment procedure, were simulated in all the 20 reconstruction samples of three-dimensional models, respectively. The peak von Mises stress on the cervical area of each model, as well as the stress distribution under vertical and oblique loading circumstances, were subsequently determined by using finite element analysis.Results:In comparison to the stresses of ConvAC [buccal cervical (BC): (188.7±13.4) MPa, palatal cervical (PC): (200.9±25.7) MPa], the stresses of TrussAC [BC: (146.0±12.9) MPa, PC: (167.6±15.9) MPa] ( t=9.01, P<0.001; t=4.59, P<0.001) and SMIAC [BC: (142.6±13.7) MPa, PC: (168.1±17.4) MPa] ( t=9.64, P<0.001; t=3.76, P=0.004) significantly reduced the peak von Mises stress on the cervical area of the maxillary first premolars after root canal treatment. Under vertical loading conditions, SMIAC also reduced the central tendency of stresses on the occlusal surface, cervical area and root. In the case of oblique loading conditions, similar results were observed. Under both loading conditions, there was no significant difference in the peak von Mises stress on the cervical area of the maxillary first premolar between TrussAC and SMIAC groups. Conclusions:The design of SMIAC could preserve the mechanical properties of the maxillary first premolar following root canal treatment, which might have certain clinical feasibility.