OBJECTIVETo analyze the stress magnitude and distribution of remaining dentin in posterior residual root restored with post-core crown by three-dimension finite element methods. The variables were number, length and material of post.

METHODSThe models of residual root of maxillary first molar restored with post-core crown were created by CT scanning, Mimics software and Abaqus software. Different number, length and material of posts were used in the modeling. The post was cemented with zinc-phosphate cement. A load of 240 N was applied to the occlusal surface in vertical direction and tensile, shear, and Von mises stresses were calculated.

RESULTSThe maximum stresses on remaining dentin changed irregularly as the number and length of post. The maximum stresses on remaining dentin decreased slightly as elastic modulus of the material of post increase.

CONCLUSIONThe number, length, material of post have influence on magnitude and distribution of stress.

Crowns ; Dentin ; Elastic Modulus ; Finite Element Analysis ; Humans ; Molar ; Post and Core Technique ; Tooth Root ; Tooth, Nonvital

[摘 要] 目的：探讨抗PD-1单抗联合化疗及抗血管生成药物治疗晚期黑色素瘤的疗效和安全性。方法：收集2020年4月至2021年6月在北京大学肿瘤医院接受抗PD-1单抗联合化疗药物替莫唑胺±顺铂、白蛋白结合型紫杉醇及抗血管生成药物贝伐珠单抗治疗的14例（男6、女8例）不可切除的晚期黑色素瘤患者的临床资料。主要研究终点为无进展生存期（PFS），次要终点为客观有效率（ORR）、疾病控制率（DCR）、总生存期（OS）及安全性数据（CTCAE 5.0标准）。结果：14例晚期黑色素瘤患者均纳入生存分析，中位随访时间为5.50个月（95% CI: 0~13.12个月），中位PFS为7.43个月（95% CI: 3.07~11.79个月），中位OS为13.50个月（95% CI: 5.19~21.81个月），中位起效时间为1.5个月；ORR为28.6%（4例均为部分缓解），DCR为85.7%；不良反应多为1~2级。结论：抗PD-1单抗联合化疗及抗血管生成药物治疗在晚期黑色素患者中显示出初步的有效性及良好的安全性，此可能为晚期黑色素瘤的联合治疗策略提供了新思路。