Graduate student, Graduate Program in Dentistry, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University, São Paulo, Brazil.
Assistant Professor, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University, São Paulo, Brazil.
J Prosthet Dent. 2017 Sep;118(3):363-371. doi: 10.1016/j.prosdent.2016.10.033. Epub 2017 Feb 17.
Slight offset of the central implant in 3-unit implant-supported prostheses has been reported to improve biomechanical behavior. However, studies that assessed the effects of an offset implant configuration in the posterior maxilla are scarce.
The purpose of this 3-dimensional (3D) finite element analysis was to assess the effects of splinting in 3-unit implant-supported prostheses with varying implant positions (straight-line or offset configuration) in terms of the stress/strain distribution on bone tissue and the stress distribution on abutment screws.
Three 3D models were used to simulate a posterior maxilla bone block (type IV): straight-line implants supporting single crowns (model M1), straight-line implants supporting 3-unit splinted fixed dental prosthesis (model M2), and an offset implant configuration supporting 3-unit splinted fixed dental prosthesis (model M3). The applied forces were 400 N axially and 200 N obliquely. The type of implant platform simulated was an external hexagon. von Mises stress on the abutment screws was measured, and the maximum principal stress and microstrain values were used to perform cortical bone tissue analysis. Analysis of variance (ANOVA) and the Tukey honest significant differences post hoc test were used to determine the significance of the results and interactions among the main variables (α=.05).
In all models, oblique load increased the stress on abutment screws and bone tissue and the microstrain on bone tissue. Model M3 decreased the stress concentration on the abutment screws and bone tissue. With regard to microstrain distribution, model M3 had the smallest values, and M1 and M2 had similar values.
Splinting associated with an offset implant configuration was effective for decreasing the stress on abutment screws and bone tissue and the microstrain on bone tissue.
报道称，在 3 单位种植体支持的修复体中，中央种植体稍有偏移可改善生物力学行为。然而，评估上颌后牙中偏移种植体配置影响的研究很少。
本三维（3D）有限元分析的目的是评估在不同种植体位置（直线或偏移配置）下，3 单位种植体支持的修复体中，夹板对骨组织的应力/应变分布和基台螺钉的应力分布的影响。
使用三个 3D 模型来模拟上颌后牙骨块（IV 型）：直线种植体支持单个牙冠（模型 M1），直线种植体支持 3 单位夹板固定义齿（模型 M2）和偏移种植体配置支持 3 单位夹板固定义齿（模型 M3）。施加的轴向力为 400 N，斜向力为 200 N。模拟的种植体平台类型为外六角。测量基台螺钉上的 von Mises 应力，并使用最大主应力和微应变值进行皮质骨组织分析。采用方差分析（ANOVA）和 Tukey 诚实显著差异事后检验来确定结果的显著性和主要变量之间的相互作用（α=0.05）。
在所有模型中，斜向负荷增加了基台螺钉和骨组织的应力以及骨组织的微应变。模型 M3 降低了基台螺钉和骨组织的应力集中。就微应变分布而言，模型 M3 的值最小，模型 M1 和 M2 的值相似。
与偏移种植体配置相关的夹板可有效降低基台螺钉和骨组织的应力以及骨组织的微应变。
