Gowda Srinivasa, Quadras Dilip D, Sesappa Rajeet S, Katapadi Vidyachandra, Kumar Lalit, Kulkarni Dinraj, Mishra Nitu
Department of Prosthodontics, Armed Forces Medical College Maharashtra University of Health Sciences, Pune, Maharashtra India, Phone: +919049866969, e-mail:
Department of Orthodontics and Dentofacial Orthopedics Srinivas Institute of Dental Sciences, Mangaluru, Karnataka, India.
J Contemp Dent Pract. 2018 Jun 1;19(6):669-674.
The aim of this study was to evaluate the effect of connector designs on scale and distribution pattern of the stress generated in the supporting bone of implant tooth-supported three-unit fixed partial denture in distal extension situation.
Three-unit fixed partial denture geometric models with implant abutment in second molar, pontic in first molar, and second premolar as mesial abutment in distal extension situations were evaluated using a two-dimensional (2D) finite element analysis. Three models were designed and constructed with mesial and distal rigid connectors, mesial nonrigid connector, and distal nonrigid connector respectively, using the software ANSYS, version 10.0 (University Intermediate). The models were analyzed to determine the maximum equivalent von Mises stress at five critical zones (maximum value) under static axial loading (240 N) after meshing and assigning the material properties.
The maximum stress concentration values at mesial and distal alveolar crest of the implant-supporting bone were 60.59 and 68.57 MPa, respectively, in Model No 1. The high equivalent von Mises stress concentration values at the mesial and distal alveolar crest of the implant-supporting bone were 1.65 and 0.747 MPa with 0.1 mm vertical movement and 7.88 and 9.34 MPa with 0.5 mm vertical movement of the connector respectively, in Model No 2. The high equivalent von Mises stress concentration values at mesial and distal alveolar crest of the implant-supporting bone were 10.45 and 3.43 MPa with 0.1 mm vertical movement and 4.50 and 5.71 MPa with 0.5 mm vertical movement of the connector respectively, in Model No 3.
In the supporting bone around the implant in Model No 1, the maximum von Mises stress concentrations were displayed in the crestal zones. In the supporting bone around the implant abutment, the von Mises stress concentrations were minimal toward the apical third zone in all the models. The stress concentrations were minimal in the supporting bone around the implant and the natural tooth in the models with nonrigid connector.
When implant is used as distal abutment in three-unit implant tooth-supported fixed partial denture with pontic at first molar in distal extension situation, it is recommended to place the nonrigid connector in the mesial side of the distal implant abutment.
本研究旨在评估在远中游离端情况下，种植体支持的三单位固定局部义齿连接体设计对支持骨中产生的应力大小及分布模式的影响。
采用二维有限元分析评估远中游离端情况下的三单位固定局部义齿几何模型，该模型中第二磨牙为种植基牙，第一磨牙为桥体，第二前磨牙为近中基牙。使用ANSYS 10.0版软件（大学中级版）分别设计并构建三个模型，分别为近远中均为刚性连接体、近中为非刚性连接体以及远中为非刚性连接体的模型。在划分网格并赋予材料属性后，对模型进行分析，以确定在静态轴向加载（240 N）下五个关键区域（最大值）的最大等效应力。
模型1中，种植体支持骨近远中牙槽嵴处的最大应力集中值分别为60.59 MPa和68.57 MPa。模型2中，种植体支持骨近远中牙槽嵴处，连接体垂直移动0.1 mm时，等效应力集中高值分别为1.65 MPa和0.747 MPa；连接体垂直移动0.5 mm时，分别为7.88 MPa和9.34 MPa。模型3中，种植体支持骨近远中牙槽嵴处，连接体垂直移动0.1 mm时，等效应力集中高值分别为10.45 MPa和3.43 MPa；连接体垂直移动0.5 mm时，分别为4.50 MPa和5.71 MPa。
在模型1种植体周围的支持骨中，最大等效应力集中出现在嵴顶区域。在种植基牙周围的支持骨中，所有模型中向根尖三分之一区域的等效应力集中最小。在具有非刚性连接体的模型中，种植体和天然牙周围支持骨中的应力集中最小。
当种植体作为远中游离端情况下第一磨牙为桥体的三单位种植体支持固定局部义齿的远中基牙时，建议在远中种植基牙的近中侧放置非刚性连接体。
