目的: 探索牙冠面开孔直径对种植修复系统及周围皮质骨应力状况的影响.方法: 建立第一磨牙缺失的下颌骨有限元模型,模拟植入Bego 种植体1 枚.建立不同开孔直径的牙冠模型(Φ = 0、1、2、3、4 mm) ,于面施加200 N 垂直力及100 N、45°侧向力,分析各部件的最大等效应力.结果: 开孔直径≤3 mm 时,牙冠咬合面所受应力保持平稳并集中在咬合力加载区.开孔直径在4 mm 时应力增长达到峰值,垂直载荷下应力集中区转变至开孔边缘处.开孔直径≤1 mm 时,中央螺丝在垂直载荷下可以维持在较低的应力水平.其余部位未见明显应力改变.结论: 在后牙区行单牙种植修复时,若不考虑体外粘接,建议将面开孔直径设置为1 mm.%Objective: To investigate the stress and stress distribution generated on each component of implant prosthodontic system and surrounding cortical bone when different diameters of screw-access hole (SAH) were prepared on molar crown. Methods: A fimite element(FE) model of partial mandible without first molar was set up, and an Bego implant was insert into it. A total of 5 models of the crown were computer-simulated by varying the diameter (Φ = 0-4 mm) of the SAH. The loading forces were 200 N axially (0°) and 100 N obliquely (45°) respectively on occlusive surface. The FE analysis was performed by computer. Results: Φ ≤3 mm: stress on occlusal surface of crown was almost unchanged and mainly distributed in the loading area. Φ = 4 mm, stress appeared an obvious rise and reached the maximum, the stress concentration under vertical load was changed to the hole margin. In vertical loading, screw could remain at a relatively low stress level when diameter did not exceed 1 mm. No changes on other components was observed. Conclusion: SAH diameter of 1 mm is recommended when a cement-and screw-retained crown is used in posterior region.
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