Department of Prosthodontics, University of Alabama at Birmingham, Birmingham, AL 35294-0007, USA.
J Prosthodont. 2009 Dec;18(8):656-62. doi: 10.1111/j.1532-849X.2009.00504.x. Epub 2009 Aug 13.
The purpose of this study was to investigate the fit of cast alloy overdenture and laser-welded titanium-alloy bars by measuring induced strain upon tightening of the bars on a master cast as well as a function of screw tightening sequence.
Four implant analogs were secured into Type IV dental stone to simulate a mandibular edentulous patient cast, and two groups of four overdenture bars were fabricated. Group I was four cast alloy bars and Group II was four laser-welded titanium bars. The cast alloy bars included Au-Ag-Pd, Pd-Ag-Au, Au-Ag-Cu-Pd, and Ag-Pd-Cu-Au, while the laser-welded bars were all Ti-Al-V alloy. Bars were made from the same master cast, were torqued into place, and the total strain in the bars was measured through five strain gauges bonded to the bar between the implants. Each bar was placed and torqued 27 times to 30 Ncm per screw using three tightening sequences. Data were processed through a strain amplifier and analyzed by computer using StrainSmart software. Data were analyzed by ANOVA and Tukey's post hoc test.
Significant differences were found between alloy types. Laser-welded titanium bars tended to have lower strains than corresponding cast bars, although the Au-Ag-Pd bar was not significantly different. The magnitudes of total strain were the least when first tightening the ends of the bar.
The passivity of implant overdenture bars was evaluated using total strain of the bar when tightening. Selecting a high modulus of elasticity cast alloy or use of laser-welded bar design resulted in the lowest average strain magnitudes. While the effect of screw tightening sequence was minimal, tightening the distal ends first demonstrated the lowest strain, and hence the best passivity.
本研究旨在通过测量杆拧紧时在主模型上产生的诱导应变以及拧紧顺序的函数来研究铸造合金义齿和激光焊接钛合金杆的适配性。
将四个种植体模拟体固定在 IV 型牙科石膏中，以模拟下颌无牙患者的模型，然后制造两组四个义齿杆。组 I 为四个铸造合金杆，组 II 为四个激光焊接钛合金杆。铸造合金杆包括 Au-Ag-Pd、Pd-Ag-Au、Au-Ag-Cu-Pd 和 Ag-Pd-Cu-Au，而激光焊接杆均为 Ti-Al-V 合金。这些杆是由同一个母模铸造的，然后拧到位，并通过粘在种植体之间的杆上的五个应变计测量杆中的总应变。每个杆都用三个拧紧顺序拧到 30 Ncm 扭矩位置 27 次。数据通过应变放大器处理，并使用 StrainSmart 软件通过计算机进行分析。数据通过方差分析和 Tukey 事后检验进行分析。
发现合金类型之间存在显著差异。激光焊接钛合金杆的应变往往低于相应的铸造杆，尽管 Au-Ag-Pd 杆没有显著差异。当第一次拧紧杆的两端时，总应变的幅度最小。
使用拧紧时杆的总应变来评估种植体义齿杆的被动性。选择高弹性模量的铸造合金或使用激光焊接杆设计可导致最低的平均应变幅度。尽管拧紧顺序的影响很小，但首先拧紧远端显示出最低的应变，从而具有最佳的被动性。
