剩余牙本质肩领位置对上颌前磨牙桩核冠受力的三维有限元分析

Influence of residual ferrule location on stress distribution of maxillary premolar restored with post-and-core crown：a three-dimensional finite element analysis

摘要:

目的：运用有限元法分析研究不同位置牙本质肩领的上颌前磨牙桩核冠修复后的各项应力分布情况。方法：将拔除的上颌前磨牙包埋于甲基丙烯酸树脂块中，结合CBCT扫描技术和有限元分析软件，建立5组不同位置的牙本质肩领桩核冠修复模型（A组：环形牙本质肩领；B组：颚侧完整牙本质肩领；C组：颊侧完整牙本质肩领；D组：近中侧完整牙本质肩领；E组：远中侧完整牙本质肩领，所有牙本质肩领高度均为2.0 mm），于颊尖舌斜面顶1/3处施加载荷为200 N，与牙体长轴呈45°的静态侧向力，分析各小组牙体硬组织应力分布情况。结果：C组最大等效应力值最大，为64.53 MPa，A组等效应力峰值最小，为50.87 MPa。B、D、E组等效应力峰值分别为55.31、60.61和59.73 MPa；最大主应力分别为43.04、43.60、47.34、45.39 和46.91 MPa。结论：保留完整的牙本质肩领可有效减少牙体组织应力集中，增强患牙抗折性；当剩余牙体组织不足时，保留鄂侧的牙本质肩领可保护粘结层的完整性并提高牙本质与树脂之间粘结层的抗折能力，从而增加患牙的抗折能力。

Abstract:

Objective：To investigate the stress distribution of maxillary premolar with different residual ferrule locations after post-core crown restoration using the finite element analysis. Methods：An extracted maxillary premolar was embedded in acrylic resin block. Cone-beam CT scan and a finite element analysis software were used to establish five models of post-core crown restoration with dif－ferent residual ferrule locations（group A：teeth with a circular ferrule；group B：teeth with a complete palatal ferrule；group C：teeth with a complete buccal ferrule；group D：teeth with a complete mesial ferrule；group E：teeth with a complete distal ferrule；the height of the ferrule was 2 mm in all groups）. A load of 200 N at a 45° angle to the long axis of the tooth was applied at the top 1/3 of the lingual surface of the buccal cusp. The maximum von Mises stress and the maximum principal stress were analyzed. Results：Group C had the highest maximum von Mises stress of 64.53 MPa，while group A had the lowest maximum von Mises stress of 50.87 MPa. The maximum von Mises stresses in group B，group D，and group E were 55.31，60.61 and 59.73 MPa，respectively. The maximum principal stresses in groups A to E were 43.04，43.60，47.34，45.39 and 46.91 MPa，respectively. Conclusion：A complete ferrule can effectively prevent stress concentration at the dentinal tissue of the tooth and enhance fracture resistance of the diseased tooth. When the re－maining dentinal tissue is not sufficient，preservation of the palatal ferrule can protect the integrity of the adhesive layer，increase the fracture resistance of the adhesive layer between the dentin and resin，and thus enhance the anti-fracture ability of the diseased tooth.