A New Procedure of a Calcium-Containing Coating on Implants of Titanium Alloy

Abstract

The paper describes a new method for converting the existing oxide layer of implants of titanium and titanium alloys in calcium containing surface layers. The layers were generated by dipping the implants in a salt melt consisting of calcium nitrate at temperatures of 520°C until 560°C for 2 until 4 hrs. The melt reacted with the surface layer of the implants by forming calcium titanate surface layers. Besides, the thickness of the TiO 2 layer of the implants became larger. Several methods for the determination of the layer thickness were investigated related to their suitability. The micro hardness of the layer and the tribological behaviour were investigated. The presented procedure can be used for generating calcium containing surface layers on implants of titanium alloys even with complicated forms.

Bony integration of titanium implants with a novel bioactive calcium titanate (Ca4Ti3O10) surface treatment in a rabbit model

“…Hereby, the partial conversion of the TiO 2 surface layer into calcium titanate is caused by the reaction with the calcium ions of the melt. By means of thin film X‐ray differentiation, it was shown that the surface layer consists of the CaO‐rich calcium titanate (Ca 4 Ti 3 O 10 ) 9. Furthermore, the calcium content of the reaction layers increased with storing time and temperature.…”

“…WIWOX GmbH; Erkrath, Germany; grain size 850–1180 μm) resulting in a roughness of R z = 40 ± 10 μm. If applicable, the calcium titanate reaction layer was generated in a salt melt as previously described 9, 10. Initially, the scaffolds were dipped into the salt melt at a temperature of 350°C for 1 h. After the treatment, scaffolds were taken out of the melt and put into an ultrasound bath to remove adhering parts followed by cleansing with water (50°C), and diluted HCl.…”

“…Initially, the scaffolds were dipped into the salt melt at a temperature of 350°C for 1 h. After the treatment, scaffolds were taken out of the melt and put into an ultrasound bath to remove adhering parts followed by cleansing with water (50°C), and diluted HCl. The treated scaffolds were then washed with distilled water and dried on air 9. Scaffolds were finally gamma‐sterilized and packed sterile.…”

“…This again might lead to a subsequent implant loosening, especially if applied to acetabular cups 4–8. The risk of loosening or flaking from the implant body is excluded by chemically converting titanium oxide (TiO 2 ) surfaces into calcium titanate 9, 10. Many beneficial effects, such as an increased cell adhesion, promotion of osteoblast adhesion and hence increasing osseointegration, have been described for the incorporation of calcium into the outer TiO 2 layer of medical implants 3, 11–16.…”

“…It may be applied by hydrothermal treatment, hydrothermal‐electrical treatment, or sol‐gel coating 3. Recently, a new procedure to incorporate calcium into titanium alloy implants has been described 9. Via this procedure, it is possible to generate calcium containing surface layer even for implants of complex shapes 9, 10…”