Introduction: Anodization is one of the known methods, to modify the surface of titanium and its alloys. In the recent past anodic spark oxidation was used to improve the surface of dental implants. In the present study, titanium surface is first modified by sand blasting and then anodization is done. The purpose of doing sand blasting is to create micro topography and that of anodization is to create nano pores. The effect of sand blasting process parameters as well as anodization process parameters (electrolyte concentration, applied voltage and time) on morphology of porous structure is studied. Process is optimized to obtain the desired micro as well as nano topography along with optimum Ra value.
Materials and Methods: For the present study, grade 23 (ELI) titanium alloy samples are used for the anodization. Anodization set up is made in-house. Platinum with 99.9% purity is used as cathode and titanium alloy grade 23 samples are used as anode. The surface area of cathode is 3 times more than anode. Hydrofluoric acid is used as electrolyte and instead of magnetic stirrer ultrasonic stirrer is used. Anodization is done at different voltage for different time durations on machined as well as sandblasted samples. Topography is observed under SEM and Ra value is measured by optical profilometer.
Results: There is decrease in pore size diameter with the increase in concentration of HF from 0.5% to 5%. At lower concentration nano pores are distinct structure but at higher concentration pores get interconnected at their walls. With the increase in the time of anodization, there is enhancement in the uniformity of pore size distribution. No significant effect of voltage variation is observed on nanopore dimensions. Ra value is significantly improved in sandblasted and anodized samples as compared to that of the only anodized samples.
Discussion: In the sand blasted and anodized sample surface, the desired Ra value and micron level topography is obtained by process of sand blasting and anodization creates nano pore topography. Nano topography is essential for the interaction of proteins which is the first step required for the cell adhesion and Micron level topography is required for better cell spreading and proliferation. In order to load the bioactive molecules or drugs, the nano pore diameter can be changed by varying the concentration of HF.
Conclusion: This study creates a path forward for improving the bioactivity of titanium surface both at micron as well as nano level. This newer surface can be further biofunctionalized or drugs loaded to produce a new generation of dental implants.
Council of Scientific and Industrial Research (CSIR)