Modelo de contato aplicado a componentes odontológicos de titânio com superfícies obtidas por diferentes processos de fabricação

Abstract

Changes in manufacturing processes used in dental components (implant/abutment) may imply different levels of surface roughness. Therefore, the interaction between them results in different contact areas with their respective stresses, affecting the performance of the set. This study investigated the effect of roughness, in different surfaces, on resulting contact stresses. For this purpose, a microscopic contact model for real surfaces was applied. The analyzed surfaces were titanium alloys (Ti-6Al-4V) and pure titanium, materials commonly used in implant dentistry. Four surfaces were analyzed: i) electro-discharge machined; ii) electro-discharge machined followed by electrolytic polishing, iii) real component of machined implant, and iv) real component of machined abutment. Roughness was determined by optical interferometry, using 3D images from different areas. In addition, the surfaces were characterized by optical and scanning electron microscopy. Contact areas were calculated using the classic Greenwood-Williamson mechanical contact model for different levels of separation between surfaces. It was found that the relationship between the Sq (root mean square roughness) and Ssc (mean summit curvature) parameters had a significant influence on the results. The higher ratio Sq / Ssc increases the contact area and generated lower stress. The single variation of Sq was less significant than the presented relationship. The surface of the abutment, with low roughness and smallest Ssc value, presented the lowest stress, although its Sq is greater than that of the implant. The greatest contact stress was generated by the electro-discharge machining, which presented the highest values Sq, Ssc and Sds (summit density) among the analyzed samples.