Effect of surface physico-chemico-biological modifications of titanium on critical and theoretical surface free energy

Abstract

AimThe aim of this study was to determine the effect of surface physico-chemico-biological modifications of titanium on critical and theoretical surface free energy. Materials and MethodsCylindrical commercially pure titanium rods (99.9%) 1.27 cm in diameter were sectioned into 2 mm thick disks and polished on silicon carbide paper from 240 to 600 grit. Discs were divided into 3 treatment groups as follows, (a) Chemical treatment group which were treated with HNO3, HF/HNO3, or H2O2/HCL; (b) Physical treatment group, which were treated with autoclaving, autoclaving + Plasma treatment, and HNO3 + Plasma Cleaning and (c) Biological treatment group which were treated with H2O2/HCl followed by attachment of Collagen II or Soaking in simulated body fluid (SBF) Kokubo recipe to form hydroxyapatite. Contact angles of three investigational liquids (20 μl), distilled water, formamide and diiodomethane on the disks were measured using a single-lens reflex camera. Six measurements were made for each treatment. Surface free energies (SFE) were determined using the Zisman method for critical surface energy, the geometric mean method and acid-base theory. Data were compared using Analysis of Variance (ANOVA) and Tukey’s honestly significant difference (HSD) test (α = 0.05). Results/ConclusionChemical treatment with HNO3 and H2O2/HCl and physical treatment by plasma cleaning of Ti surfaces resulted in significantly higher SFE compared to untreated Ti in all the different approaches for surface free energy determination. The geometric mean method and acid-base theory revealed that increases in SFE were due to increases in the polar and base components of surface energy. Biologically treated surface showed consistent increases in the acid component of surface energy although not statistically significantly different from controls. Information about the effect of surface treatments on SFE and its components provide insights into the preferred surface characteristics for facilitation of cellular activities on implant materials for osseo- and chondro- integration.