Centro de Química Estrutural (CQE), Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.
Centro de Investigação Interdisciplinar Egas Moniz (CiiEM), Instituto Universitário Egas Moniz, Monte da Caparica, Portugal.
J Mech Behav Biomed Mater. 2019 Mar;91:164-173. doi: 10.1016/j.jmbbm.2018.12.009. Epub 2018 Dec 13.
Loosening and fracture of implanted dental crowns is a consequence of relative micromovements between the zirconia abutment and the titanium alloy of the implant, in a biochemical aggressive environment. Thus, it is important to establish the in vitro tribological testing conditions that better mimics such environment. The present work aims to evaluate the effect of ball-on-plate tests configuration on the tribological behavior of ZrO/Ti6Al4V pair in dry and lubricated conditions, using different lubricants: water, artificial saliva solution and human saliva. Ceramic balls sliding on metallic plates (TiPlate) and metallic balls sliding on ceramic plates (TiBall) were tested and the coefficient of friction (CoF) and wear response was monitored trough nanotribological tests. Open circuit potential was also measured during the tests carried out in saline solution (artificial saliva) to access the tribochemical response. The wear mechanisms were evaluated by scanning electron microscopy and atomic force microscopy analysis. Relevant differences were found between the two configurations, with and without the presence of human saliva: TiPlate presented always a higher CoF than TiBall, which may have resulted from differences in the degradation and regeneration processes of the titanium passive film during sliding. TiBall demonstrated to be the best choice to reproduce the in vivo conditions, since the metallic surface contacts permanently with zirconia, impairing the titanium repassivation. Regarding the effect of the lubricants, it was observed that human saliva had a protective action of the surfaces, leading to the lowest CoF among the lubricants used (0.19 ± 0.05 for TiBall and 0.35 ± 0.08 for TiPlate) and neglectable wear.
种植体牙冠松动和断裂是氧化锆基台与种植体钛合金在生化侵蚀环境中发生相对微动的结果。因此，建立更好模拟这种环境的体外摩擦学测试条件非常重要。本工作旨在评估球盘试验配置对干燥和润滑条件下 ZrO/Ti6Al4V 对摩擦行为的影响，使用了不同的润滑剂：水、人工唾液溶液和人唾液。测试了陶瓷球在金属板（TiPlate）上滑动和金属球在陶瓷板（TiBall）上滑动，并通过纳米摩擦学测试监测摩擦系数（CoF）和磨损响应。在盐溶液（人工唾液）中进行的测试还测量了开路电位，以评估摩擦化学响应。通过扫描电子显微镜和原子力显微镜分析评估了磨损机制。在存在和不存在人唾液的两种配置之间发现了相关差异：TiPlate 的 CoF 始终高于 TiBall，这可能是由于滑动过程中钛钝化膜的降解和再生过程存在差异所致。TiBall 被证明是再现体内条件的最佳选择，因为金属表面与氧化锆永久接触，阻碍了钛的再钝化。关于润滑剂的影响，观察到人唾液对表面具有保护作用，导致使用的润滑剂中 CoF 最低（TiBall 为 0.19±0.05，TiPlate 为 0.35±0.08），磨损可忽略不计。
