Physicochemical Properties and Biological Response of Titanium Surface Modified by Anodic Spark Deposition for Dental Implants

Abstract

Surface modifications play a significant role in the interaction and success of implants to adjacent tissues. This study evaluated the surface topography and in vitro cellular response of surface treatments on titanium performed by multiphase anodic spark deposition (ASD). The titanium surfaces examined were: BioSpark (BS) and OsseoSpark (OS), obtained by ASD method; BioRough™ (BR), a chemical etching treatment used for comparison; and commercially-pure grade-2 titanium (cpTi) used as a control. The samples were cut in discs (12 mm diameter; 0.5 mm thickness) and sterilised by λ-irradiation prior to use. All samples were imaged using Scanning Electron Microscopy (SEM) (Hitachi S-3500N, Hitachi High-Technologies) to characterise the surface in 2 dimensions. Atomic Force Microscopy (AFM) (Topometrix Explorer SPM, Veeco Metrology LLC, CA, USA) was performed in contact mode to investigate topography in 3 dimensions and qualitatively analyse the surface roughness. Physicochemical analysis was also performed using energy dispersive X-ray spectroscopy (EDS) (Oxford Instruments Microanalysis, UK). A human osteosarcoma cell line (HOS TE85) was used for in vitro analysis; MTT assay to determine cell metabolic activity and Alamar Blue™ (Serotec) for assessing cell proliferation. SEM images indicated that ASD treatment created a microrough surface with a web-like nanostructure. AFM images illustrated the 3-dimensional topographies and quantitatively analysed surface roughness by ranging from the roughest to the smoothest which were Br > OS > BS > cpTi, respectively. Cellular response results showed no toxic leachables released from the test samples, thus indicating all sample were biocompatible. A good level of cell proliferation compared to the control was observed indicating a favourable attachment surface. This study has indicated that the ASD treatment surface has a nanostructure topography favouring cell attachment and proliferation and can potentially be used to improve titanium performance by enhancing osseointegration for use in dental implantology.