title: Effect of anodization and alkali-heat treatment on the bioactivity of titanium implant material (an in vitro study).
abstract: OBJECTIVE
  This study was aimed to assess the effect of anodized and alkali-heat surface treatment on the bioactivity of titanium alloy (Ti-6Al-4V) after immersion in Hank's solution for 7 days.
  
  
  METHODS
  Fifteen titanium alloy samples were used in this study. The samples were divided into three groups (five for each), five samples were anodized in 1M H3PO4 at constant voltage value of 20 v and another five samples were alkali-treated in 5 M NaOH solution for 25 min at temperature 60°C followed by heat treatment at 600°C for 1 h. All samples were then immersed in Hank's solution for 7 days to assess the effect of surface modifications on the bioactivity of titanium alloy. The different treated surfaces and control one were characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transformation infra-red spectroscopy. Statistical analysis was performed with PASW Statistics 18.0(®) (Predictive Analytics Software).
  
  
  RESULTS
  Anodization of Ti-alloy samples (Group B) led to the formation of bioactive titanium oxide anatase phase and PO4 (3-) group on the surface. The alkali-heat treatment of titanium alloy samples (Group C) leads to the formation of bioactive titania hydrogel and supplied sodium ions. The reaction between the Ti sample and NaOH alkaline solution resulted in the formation of a layer of amorphous sodium titania on the Ti surface, and this layer can induce apatite deposition.
  
  
  CONCLUSIONS
  The surface roughness and surface chemistry had an excellent ability to induce bioactivity of titanium alloy. The anodization in H3PO4 produced anatase titanium oxide on the surface with phosphate originated from electrolytes changed the surface topography and allowed formation of calcium-phosphate.
authors.affiliation: Department of Dental Biomaterials, School of Dentistry, Al-Azhar University, Egypt, Kingdom of Saudi Arabia; Department of Restorative Dental Sciences, Alfarabi Colleges, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Ramy A
authors.initials: RA
authors.lastname: Abdelrahim
authors.affiliation: Department of Dental Biomaterials, Faculty of Oral and Dental Medicine, Cairo University, Egypt.
authors.forename: Nadia A
authors.initials: NA
authors.lastname: Badr
authors.affiliation: Department of Preventive Dental Sciences, Alfarabi Colleges, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Kusai
authors.initials: K
authors.lastname: Baroudi
keywords: Alkali-heat treatment; anodization; bioactivity; surface roughness