IADR Abstract Archives
Bioactive Coatings Produced by Micro-arc Oxidation: Characterization and Tribocorrosion Behavior
Objectives: Titanium (Ti) and its alloys are commonly used in dental applications. During mastication, dental implants are submitted to complex physiological loads and are exposed to mechanical, chemical and biological aggressive environment leading to implant failures. Thereby, the synergistic interaction of wear and corrosion (i.e. tribocorrosion) accelerates material degradation. The objectives were: (i) To create bioactive Ti-coatings doped with calcium (Ca) and phosphorous (P) by micro-arc oxidation (MAO) to improve chemical and mechanical properties for implants surfaces and (ii) to investigate their tribocorrosive behavior.
Methods: 15 commercially-pure titanium discs (15x2mm) were used. Samples were divided into 5 groups (n=3) as a function of different Ca/P concentrations (0.3M/0.02M and 0.1M/0.03M) and treatment duration (5 and 10 minutes). Smooth surface was used as control. MAO was carried out using pulsed DC power supply at 290V and 250Hz. Vicker's microhardness, x-ray diffraction, scanning electron microscopy and atomic force microscopy were performed to characterize the surface. In tribocorrosion test, a tribometer coupled to a potentiostat was used to evaluate the potential drops during sliding. The sliding duration (2000 cycles) and frequency (1Hz) parameters were selected to simulate the oral environments under 5N load and 3mm stroke. ANOVA and Tukey’s HSD tests were used (α=.05).
Results: Porous oxide layers enriched with bioactive elements were obtained. Higher Ca concentration produced larger porous and also harder coatings when compared to control group (p<0.001), due to the presence of rutile crystalline structure. Free potentials experiments showed lower drops (-0.6V) and higher coating lifetime during sliding (5 and 7 minutes) for higher Ca concentration, whereas the lower concentrations presented similar drops (-0.8V) in comparison to control group wherein the drop occurred immediately after the sliding started.
Conclusions: Higher Ca/P ratios presented better surface properties and tribocorrosive behavior. MAO is a promising technique to enhance chemical and mechanical properties of dental implants surfaces.
Methods: 15 commercially-pure titanium discs (15x2mm) were used. Samples were divided into 5 groups (n=3) as a function of different Ca/P concentrations (0.3M/0.02M and 0.1M/0.03M) and treatment duration (5 and 10 minutes). Smooth surface was used as control. MAO was carried out using pulsed DC power supply at 290V and 250Hz. Vicker's microhardness, x-ray diffraction, scanning electron microscopy and atomic force microscopy were performed to characterize the surface. In tribocorrosion test, a tribometer coupled to a potentiostat was used to evaluate the potential drops during sliding. The sliding duration (2000 cycles) and frequency (1Hz) parameters were selected to simulate the oral environments under 5N load and 3mm stroke. ANOVA and Tukey’s HSD tests were used (α=.05).
Results: Porous oxide layers enriched with bioactive elements were obtained. Higher Ca concentration produced larger porous and also harder coatings when compared to control group (p<0.001), due to the presence of rutile crystalline structure. Free potentials experiments showed lower drops (-0.6V) and higher coating lifetime during sliding (5 and 7 minutes) for higher Ca concentration, whereas the lower concentrations presented similar drops (-0.8V) in comparison to control group wherein the drop occurred immediately after the sliding started.
Conclusions: Higher Ca/P ratios presented better surface properties and tribocorrosive behavior. MAO is a promising technique to enhance chemical and mechanical properties of dental implants surfaces.