下颌第一磨牙邻面大面积缺损不同修复方案的生物力学效果

Biomechanical effect of different restoration schemes for large medial-occlusal cavities of mandibular first molar

目的比较下颌第一磨牙邻面大面积缺损不同修复方案的生物力学效果。方法采用三维有限元法建立不同的下颌第一磨牙修复方案模型,模拟正常人咬合;施加垂直和45度斜向加载,记录纤维桩加强全冠和髓腔固位冠两种不同修复方式下剩余牙体组织和修复体等效(EQV)应力大小和分布。结果施加垂直加载或斜向加载后,纤维桩加强全冠组和髓腔固位冠组剩余牙体组织的应力分布均集中于牙颈部,且纤维桩加强全冠组的EQV应力峰值高于髓腔固位冠组。而纤维桩加强全冠组修复体的EQV应力集中于冠颈部边缘,髓腔固位冠组修复体的应力集中于髓腔粘接面,髓腔固位冠组的EQV应力峰值高于纤维桩加强全冠组。结论髓腔固位冠可有效降低剩余牙体组织EQV应力和冠折的可能性。

Objective To compare the biomechanical effect of different restoration schemes for large medial-occlusal cavities of mandibular first molar. Methods Three-dimensional finite element method was used to establish the mandibular first molar repair programme model for simulating the normal occlusion. With vertical or 45 degrees oblique load, the size and distribution of equivalent stress on the residual tooth tissues and restoration of the mandibular first molar were recorded under the two different repair modes of fiber post reinforced crown and endocrown. Results Under two kinds of load, the stress distribution of the teeth in groups of fiber post reinforced crown and endocrown were both concentrated in the neck of the tooth. The peak of equivalent stress of the teeth in fiber post reinforced crown group was higher than that in endocrown group. The equivalent stress of restoration in fiber post reinforced crown group focused on the edge of the crown, which in endocrown group focused on the adhesive surface of the medullary cavity. The peak of equivalent stress of restoration in endocrown group was higher than that in fiber post reinforced crown group. Conclusion Endocrown can effectively reduce the stress of dental tissues and the possibility of crown fracture.