Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, São Paulo, Brazil.
Int J Oral Maxillofac Implants. 2013 May-Jun;28(3):e161-70. doi: 10.11607/jomi.2481.
To evaluate the effectiveness of three types of abutments in the maintenance of screw joint preload before and after cyclic loading as well as to observe possible microdamage in the structure of the components using a scanning electron microscope (SEM).
Forty-five external-hex implants were embedded in epoxy resin, received their respective abutments, and were randomly divided into three experimental groups (n = 15): (1) machined titanium (Ti) abutments; (2) pre-machined gold (Au) abutments; and (3) machined zirconia (ZrO(2)) abutments. The abutment screws were tightened according to the manufacturer's recommended torque. Initially, a static bending test was performed using five specimens of each group to determine the load applied in the cyclic loading test. Thus, 10 specimens of each group were used to measure the reverse torque value (preload) of the abutment screw before and after loading. A cyclic loading (0.5 × 10(6) cycles; 15 Hz) between 11 and 211 N was applied at an angle of 30 degrees to the long axis of the implants. The group means were compared using analysis of variance and the Tukey test (α = .05).
The reverse torque analysis before cyclic loading showed no significant difference among the groups (P > .05). After cyclic loading, all preload means decreased significantly. The lowest decrease in preload was observed in the Ti group, whereas the highest decrease was observed in the ZrO(2) group, with a significant difference noted between them (P = .010). The Au group presented an intermediate decrease, with no significant difference compared to the other groups (P > .05). SEM images showed structural changes in the mating surfaces of the abutments after cyclic loading.
The load application reduced the preload means significantly in all groups, and more significantly in the ZrO(2) group.
评估三种类型的基台在循环加载前后维持螺丝连接预紧力的有效性，并通过扫描电子显微镜（SEM）观察部件结构中可能存在的微损伤。
将 45 个外六角种植体嵌入环氧树脂中，分别连接相应的基台，然后随机分为三组（每组 15 个）：（1）加工钛（Ti）基台；（2）预制金（Au）基台；（3）加工氧化锆（ZrO2）基台。按照制造商推荐的扭矩拧紧基台螺丝。首先，对每组的五个样本进行静态弯曲试验，以确定循环加载试验中的施加负载。因此，每组使用 10 个样本测量加载前后基台螺丝的反向扭矩值（预紧力）。以种植体长轴成 30 度角施加 11 到 211 N 的循环负载（0.5×10^6 次；15 Hz）。使用方差分析和 Tukey 检验（α=0.05）对组均值进行比较。
循环加载前的反向扭矩分析显示各组间无显著差异（P＞0.05）。循环加载后，所有预紧力均值均显著下降。Ti 组的预紧力下降幅度最小，ZrO2 组的预紧力下降幅度最大，两者之间有显著差异（P=0.010）。Au 组的预紧力下降幅度居中，与其他两组相比无显著差异（P＞0.05）。SEM 图像显示循环加载后基台的配合面出现结构变化。
所有组的负载应用均显著降低了预紧力均值，ZrO2 组的降幅更显著。
