Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Simultaneous degradation by corrosion and wear of titanium in artificial saliva containing fluoridesPublication . Souza, Júlio C.M.; Barbosa, S. L; Ariza, E.; Celis, J-P.; Rocha, L. A.The degradation of titanium-based oral rehabilitation systems can occur by corrosion and wear processes taking place simultaneously (tribocorrosion) and influenced by the presence of fluorides. In this study, the tribocorrosion behavior of titanium in artificial saliva solutions containing fluorides is investigated. Before sliding tests were started up, electrochemical measurements such as open circuit potential (OCP) and impedance spectroscopy (EIS) were performed to get information on the corrosion behavior of titanium in artificial saliva solutions. Then, sliding wear tests were carried out at the OCP taken by the test sample. Scanning electron microscopy and weight loss measurements were performed after the tribocorrosion tests. The presence of a compact passive surface film on titanium immersed was demonstrated in artificial saliva free of fluorides and in presence of up to 227 ppm F-. However, a progressive degradation of titanium was observed at a F- concentration of 12,300 ppm. Additionally, the corrosion and wear resistance of the titanium oxide film formed at a F- concentration of 12,300 ppm differ from the ones obtained up to 227 ppm F- reflected by a decrease of the coefficient of friction although the material loss increased. The synergism between wear and corrosion processes on titanium needs thus to be further investigated to reach a reliable prediction of the long-term behavior of titanium-based prostheses and implants in the oral cavity.
- Detorque Evaluation of Dental Abutment Screws after Immersion in a Fluoridated Artificial Saliva SolutionPublication . Duarte, Antônio; Silva Neto, João; Souza, Júlio C.M.; Bonachela, WellingtonPurpose: Implant-abutment connections still present failures in the oral cavity due to the loosening of mechanical integrity by detorque and corrosion of the abutment screws. The objective of this study was to evaluate the detorque of dental abutment screws before and after immersion in fluoridated solutions. Materials and Methods: Five commercial implant-abutment assemblies were assessed in this investigation: (C) Conex˜aoR , (E) EmfilsR , (I) INPR , (S) SINR , and (T) Titanium FixR . The implants were embedded in an acrylic resin and then placed in a holding device. The abutments were first connected to the implants and torqued to 20Ncm using a handheld torque meter. The detorque values of the abutments were evaluated after 10 minutes. After applying a second torque of 20 Ncm, implant-abutment assemblies were withdrawn every 3 hours for 12 hours in a fluoridated solution over a period of 90 days. After that period, detorque of the abutments was examined. Scanning electronicmicroscopy (SEM) associated to energy dispersive spectroscopy (EDS)was applied to inspect the surfaces of abutments. Results: Detorque values of systems C, E, and I immersed in the fluoridated solution were significantly higher than those of the initial detorque. ANOVA demonstrated no significant differences in detorque values between designs S and T. Signs of localized corrosion could not be detected by SEM although chemical analysis by EDS showed the presence of elements involved in corrosive processes. Conclusion: An increase of detorque values recorded on abutments after immersion in fluoridated artificial saliva solutions was noticed in this study. Regarding chemical analysis, such an increase of detorque can result from a corrosion layer formed between metallic surfaces at static contact in the implant-abutment joint during immersion in the fluoridated solutions.