不同材料嵌体修复邻牙合(Ⅱ类)洞型的应力影响分析

The stress distribution analysis of the medial-occlusal(classⅡ) cavity restored with different inlay

目的:分析不同材料嵌体修复邻(II类)洞型后牙体、嵌体的应力改变及分布。方法:建立不同材料嵌体修复邻(II类)近中-(MO)洞型三维有限元模型,求解分析各模型中垂直、侧向力(舌向45°)加载条件下牙体、嵌体主应力峰值及接触界面Von-mises峰值,并分析应力分布情况。结果:高弹性模量嵌体材料及其修复后的牙体应力峰值比低弹性模量嵌体材料高,2种加载下4种材料对牙体、嵌体应力分布趋势相似;侧向加载明显高于垂直加载。牙体应力峰值在洞底部牙本质近牙髓腔的位置;嵌体的应力峰值分布主要在其所对应的龈壁处。在牙体,其与嵌体的接触缘处的应力趋势表现为树脂>瓷>金合金>钴铬合金;在嵌体,其与牙体的接触处应力趋势为钴铬>金合金>瓷>树脂。结论:邻(II类)洞型嵌体修复后与龈壁对应处是嵌体的薄弱部位,洞底部近髓腔处是牙体的薄弱部位;与其它3种材料相比,树脂嵌体在同等载荷下牙体应力峰值小且分布均匀,自身受力较小,因此发生牙体折裂及微渗漏的可能性较小。

Objective：To analyse the stress distribution of the tooth and inlay with the restoration of resin,porcelain,gold alloy,co-balt chromium materials respectively.Methods：3-D finite element models of mandibular first molar with meiso-occlusal （classⅡ） cavity and different inlays were established.Von-mises stress distribution on the tooth and inlay with vertical load and lingual load at 45＆#176;were analyzed.Results：After restoration peak stress of high elastic module materials and dental inlays was higher than that of the low elastic module material inlays,however,the restorations of the different elastic module materials had the similar stress distribution trend.The stress under of lateral load（lingual at 45°）to the teeth inlays was significantly higher than that under vertical load.Peak stress concentration of tooth was on the bottom of the cavity near the pulp chamber dentin;inlay peak stress distribution is mainly in its corresponding to the gingival wall.In the tooth tissues stress level of the contact surface of inlay restoration,the strength was as the fol-lowing：Composite resin inlay 〉ceramics inlay 〉the gold alloy ceramics inlay 〉cobalt chromium alloy inlay.The stress level of the inlay of the four kinds of inlay restoration materials was just opponent with the tooth tissues.Conclusion：Gingival wall is the weakest part of meiso-occlusal（classⅡ）cavity inlay restoration,while near the pulp chamber at the bottom of the cavity is the weakest part of the tooth.Among the 4 materials Under the same load condition,composite resin inlay restoration has minimal tooth stress and uniform stress distribution,and can reduce the posibility of odontoschism and microleakage.