Joshi Shikha, Kumar Sandeep, Jain Shashikala, Aggarwal Rajnish, Choudhary Sunita, Reddy Nandalur K
Department of Prosthodontics, Surendera Dental College and Research Institute, Sri Ganganagar, Rajasthan, India.
Department of Prosthodontics, Surendera Dental College and Research Institute, Sri Ganganagar, Rajasthan, India, Phone: +91 9024606318, e-mail:
J Contemp Dent Pract. 2019 Jul 1;20(7):794-800.
Proper stress distribution on dental implants is necessary in bar-retained implant overlay dentures. The purpose of the study is to comparatively assess the stress distribution pattern on the crestal bone at the bone-implant interface due to different bar heights using finite element models (FEMs).
Eight 3D FEMs were developed from mandibular overdentures with two implants in the canine region separated by a distance of 20 mm. In these models, four different bar heights from the mucosa (0.5, 1, 1.5, and 2 mm) with 12 mm occlusal plane height were analyzed. A unilateral and a bilateral vertical load of 150 N were applied to the central occlusal fossa of the first molar and the stress of bone around the implant was analyzed by finite element analysis (FEA).
By increasing the bar height, the maximum stress values around implants on the crestal bone were found to be increased in unilateral and bilateral loading models. In unilateral loading models, the maximum stress was found in a model with a 2 mm bar height (0.46 MPa) on the distal side of the ipsilateral implant, and in bilateral loading cases, the maximum stress was also found in a model with a 2 mm bar height (0.456 MPa).
As the vertical cantilever increases (here the bar height), the maximum stress on the crestal bone increases. A minimum of 0.5 mm of space is sufficient between the mucosa and the inferior border of the bar to maintain oral hygiene.
From the present study, it can be concluded that an increase in bar height causes an increase in stress levels on the peri-implant crestal bone.
在杆卡式种植覆盖义齿中，牙种植体上适当的应力分布是必要的。本研究的目的是使用有限元模型（FEM）比较评估不同杆高度下种植体-骨界面处牙槽嵴骨上的应力分布模式。
从下颌覆盖义齿建立八个三维有限元模型，在尖牙区有两颗种植体，间距为20mm。在这些模型中，分析了距黏膜四种不同的杆高度（0.5、1、1.5和2mm），咬合平面高度为12mm。在第一磨牙的中央咬合窝施加150N的单侧和双侧垂直载荷，并通过有限元分析（FEA）分析种植体周围骨的应力。
通过增加杆高度，发现在单侧和双侧加载模型中，种植体周围牙槽嵴骨上的最大应力值增加。在单侧加载模型中，在同侧种植体远侧杆高度为2mm的模型中发现最大应力（0.46MPa），在双侧加载情况下，在杆高度为2mm的模型中也发现最大应力（0.456MPa）。
随着垂直悬臂增加（此处为杆高度），牙槽嵴骨上的最大应力增加。黏膜与杆下缘之间至少0.5mm的间隙足以维持口腔卫生。
从本研究可以得出结论，杆高度的增加会导致种植体周围牙槽嵴骨上的应力水平增加。
