Pessoa Roberto S, Bezerra Fábio J B, Sousa Ravel M, Vander Sloten Jos, Casati Marcio Zaffalon, Jaecques Siegfried V N
Faculty of Odontology, Federal University of Uberlandia, Uberlandia, Brazil.
J Periodontol. 2014 Sep;85(9):1161-71. doi: 10.1902/jop.2014.130633. Epub 2014 Mar 17.
It is not yet well understood to what extent different implant-abutment mismatch sizes and implant-abutment connection types may influence the peri-implant biomechanical environment of implants in different clinical situations.
Computed tomography-based finite element models comprising a maxillary central incisor socket and 4.5 × 13 mm outer-diameter implants with external and internal hex connection types were constructed. The abutments were designed with diameters of 3.5 mm (platform switching [PS] with 1 mm of diametral mismatch [PS - 1]), 4.0 mm (PS with 0.5 mm of diametral mismatch [PS - 0.5]), and 4.5 mm (conventional matching implant-abutment design [CD]). Analysis of variance at the 95% confidence interval was used to evaluate peak equivalent strain (EQV strain) in the bone, bone volume affected by a strain >4,000 με (EQV strain >4,000 με), the peak von Mises stress (EQV stress) in abutment screw, and the bone-implant relative displacement.
Similar bone strain levels (EQV strain and EQV strain >4,000 με) were encountered in PS - 1, PS - 0.5, and CD models for immediately placed implants, independent of the connection type. For immediately loaded implants, slightly smaller peak EQV strain and EQV strain >4,000 με were found for PS - 1. However, for both connection types in osseointegrated models, the higher the mismatch size, the lesser the amount of strain found.
The increase in mismatch size of PS configuration results in a significant decrease of strain levels in bone for osseointegrated implants, principally for external hex connections. No significant effect of PS could be noted in immediately placed implants.
在不同临床情况下，不同种植体-基台不匹配尺寸和种植体-基台连接类型对种植体周围生物力学环境的影响程度尚未得到充分理解。
构建基于计算机断层扫描的有限元模型，包括上颌中切牙牙槽窝以及外径为4.5×13 mm、具有外六角和内六角连接类型的种植体。基台设计直径为3.5 mm（平台转换[PS]，直径不匹配1 mm[PS - 1]）、4.0 mm（PS，直径不匹配0.5 mm[PS - 0.5]）和4.5 mm（传统匹配种植体-基台设计[CD]）。采用95%置信区间的方差分析来评估骨中的峰值等效应变（EQV应变）、应变>4000 με（EQV应变>4000 με）影响的骨体积、基台螺钉中的峰值冯·米塞斯应力（EQV应力）以及骨-种植体相对位移。
对于即刻植入的种植体，PS - 1、PS - 0.5和CD模型中遇到的骨应变水平（EQV应变和EQV应变>4000 με）相似，与连接类型无关。对于即刻加载的种植体，PS - 1的峰值EQV应变和EQV应变>4000 με略小。然而，对于骨结合模型中的两种连接类型，不匹配尺寸越高，发现的应变量越少。
PS构型不匹配尺寸的增加导致骨结合种植体骨中应变水平显著降低，主要是对于外六角连接。对于即刻植入的种植体，未发现PS有显著影响。
