Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
Int J Oral Maxillofac Implants. 2012 Nov-Dec;27(6):1474-80.
To evaluate the effect of functional cyclic loading on two retrieved abutment screws used with single implant supporting cement-retained porcelain-fused-to-metal crowns by characterizing the structure, properties, and biotribologic behavior after long-term use in vivo.
Two abutment screws were retrieved from the same patient and same implant at two different times. An external hex implant was used to replace a missing central incisor. A traumatic incident occurred 9 months after insertion and displaced the implant palatally by bending the screw. A second, similar incident occurred 31 months after insertion. In both cases, the abutment screws were retrieved and subjected to thorough nondestructive and destructive testing.
Light and scanning electron microscopic examinations revealed very minimal surface deterioration of the thread profile for the first screw (in service for 9 months) and demonstrated advanced metal adhesive wear in the form of galling for the second screw (in service for 31 months). The galling led to moderate thinning of the thread profile. Both screws were composed of Au-based alloy, where the microstructure of the matrix consisted of homogeneous equiaxed fine grains with two different second phase particles.
It appears that the occurrence of adhesive wear on abutment screws in the form of galling is highly related to the length of in-service time in the mouth. This biotribologic behavior was inevitable and considered to be a normal consequence of long-term use in vivo. Metallurgic analysis indicated that both screws were identical in terms of composition and microstructure.
通过对长期体内使用后的结构、性能和生物摩擦学行为进行特征分析，评估功能性循环载荷对 2 个用于单种植体支持的水泥固位烤瓷金属冠的回收基台螺丝的影响。
从同一患者和同一种植体的 2 个不同时间取出 2 个基台螺丝。使用外六方种植体代替缺失的中切牙。种植后 9 个月发生创伤事件，螺丝弯曲导致种植体向腭侧移位。种植后 31 个月再次发生类似事件。在这两种情况下，均取出基台螺丝并进行了彻底的非破坏性和破坏性测试。
光镜和扫描电镜检查显示，第一个螺丝（使用 9 个月）的螺纹轮廓表面仅略有恶化，而第二个螺丝（使用 31 个月）则表现出严重的金属粘着磨损形式的胶合。胶合导致螺纹轮廓中度变薄。两个螺丝均由 Au 基合金组成，基体的微观结构由均匀的等轴细晶粒和两种不同的第二相颗粒组成。
似乎基台螺丝粘着磨损形式的胶合发生与在口腔中的服役时间长度密切相关。这种生物摩擦学行为是不可避免的，被认为是长期体内使用的正常后果。冶金分析表明，这两个螺丝在成分和微观结构方面完全相同。
