Clelland N L, Papazoglou E, Carr A B, Gilat A
College of Dentistry, Ohio State University, Columbus 43210-1241, USA.
J Prosthodont. 1995 Dec;4(4):243-50. doi: 10.1111/j.1532-849x.1995.tb00350.x.
To measure and compare strains transferred to a bone simulant by screw-fastening implant overdenture bars with various levels of fit or misfit.
Photoelastic resin was cast directly to two 3.75 X 13-mm Branemark fixtures (Nobelpharma USA Inc, Chicago, IL) situated 20 mm apart in a silicone mold of an edentulous mandible. Two strain-gauge rosettes were also incorporated in the resin to allow precise determination of principal stresses at two locations. Four groups of three overdenture bars with 0-, 180-, 360-, and 500-micrometer vertical gaps were fabricated. These bars were sequentially secured to the abutments with gold slot screws tightened to 10 N-cm. Strain indicator readings were recorded at a standardized time following the initial fastening of each bar. The test was repeated three times for each overdenture bar.
Mean principal stresses and strains at the location of the rosettes were determined. The magnitude of these stresses and strains increased significantly with each increase in gap size. Strains were several times larger mesial to the fixture than they were distal.
Strains are transferred to the bone when misfitting prostheses were secured. Some of the strains mesial to the fixture appeared to be unfavorable for regions of lower bone density when the groups with designed gaps were secured. These data will be compared with those in ongoing animal studies regarding the cellular response to prosthesis misfit.
测量并比较通过螺丝固定不同贴合度或不贴合度的种植覆盖义齿杆传递至骨模拟物的应变。
将光弹性树脂直接浇铸到两个3.75×13毫米的Branemark种植体（美国诺贝尔制药公司，伊利诺伊州芝加哥）上，这两个种植体在无牙下颌骨的硅橡胶模型中相距20毫米。树脂中还嵌入了两个应变片式应变花，以便精确测定两个位置的主应力。制作了四组覆盖义齿杆，每组三根，垂直间隙分别为0、180、360和500微米。这些杆依次用金槽螺丝固定到基台上，拧紧至10牛厘米。在每根杆初次固定后的标准时间记录应变指示器读数。每个覆盖义齿杆重复测试三次。
确定了应变花位置处的平均主应力和应变。随着间隙尺寸的每次增加，这些应力和应变的大小显著增加。种植体近中侧的应变比远中侧大几倍。
固定不贴合的假体时，应变会传递至骨。当固定有设计间隙的组时，种植体近中侧的一些应变似乎对骨密度较低的区域不利。这些数据将与正在进行的关于假体不贴合的细胞反应的动物研究数据进行比较。
