面开孔直径对种植修复系统及周围皮质骨影响的有限元分析

The effect of diameter of the screw-access hole on the implant prosthodontic system and surrounding cortical bone-A 3D finite element analysis

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 （Ф=0、1、2、3、4mm） 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： ≤31nm stress on oeclusal surface of crown was almost unchanged and mainly distributed in the loading area. Ф = 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 ram. 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.