[What is thought of the various surface treatments of biomaterials used in dental and maxillofacial implantology?]. / Que faut-il penser des différents traitements de surface sur les biomatériaux utilisés en implantologie dentaire et maxillo-faciale?

The surface treatments for biomaterials have the following goals: to increase the biocompatibility and the tissue acceptation, to prevent infection to reduce the abrupt interfaces; to favour the biological integration and the long term in service behaviour. Advantages and inconveniences of these methods are analysed for the main biomaterials categories: metals, synthetic polymers, ceramics, materials of biological origin. In addition to appropriate physico-chemical and mechanical properties, the existence of biologically functional interfaces with the living cells is more and more wished. In the next 20 years, it appears likely that the design of prostheses or implants in actual clinical use will have to be totally or partly reconsidered.

Surface characterization of C/Ti-6Al-4V coating treated with ion beam.

Surface of titanium alloy (Ti-6AI-4V) has been modified by ion beam mixing of thin C film. X-ray photoelectron spectroscopy analysis showed that after mixing, the surface film consists essentially of a Ti compound containing (Ti, O and C), TiO2, Ti and C contamination. The composition of the surface modified film determined by Rutherford backscattering spectrometry is approximately Ti0.5O0.3C0.2 and its thickness is about 200 nm. After three months immersion in a simulated body fluid, the growth of calcium phosphate species containing both HPO4- and H2PO4- (probably CaHPO4 and Ca(HPO4)2) have been observed. Titanium is found to be essentially composed of the Ti compound after immersion suggesting that both metallic Ti and TiO2 have dissolved.

[Rutherford back-scattering spectrometry and photoelectron spectroscopy of the calcium/titanium interface]. / Etude par spectrométrie de rétrodiffusion de Rutherford (RBS) et par spectroscopie de photoélectrons (XPS) des interfaces calcium/titane.

Evaporation of calcium on commercially pure titanium was performed. Heatings under vacuum or oxygen flow improved calcium diffusion in the titanium substrate. X-Ray Photoelectron Spectroscopy did not revealed any superficial segregation of titanium but revealed the formation of CaCO3. The film formed on titanium was characterized using X-ray photoelectron spectroscopy with argon-ion sputtering. The results indicated that: the surface layer consisted of CaCO3; the interface contained CaCP3, CaO et TiO2; only CaO was present in the bulk titanium.

Cytocompatibility of Ti-6Al-4V and Ti-5Al-2.5Fe alloys according to three surface treatments, using human fibroblasts and osteoblasts.

Titanium alloys are well known for their superior mechanical properties as well as for their good biocompatibility, making them desirable as surgical implant materials. However, these alloys have been proven to behave poorly in friction since wear particles were often detected in tissues and organs associated with titanium implants. In this paper, three surface treatments were investigated in order to improve the wear resistance and the hardness of Ti-6Al-4V and Ti-5Al-2.5Fe: (a) glow discharge nitrogen implantation (10(17) atoms cm-2), (b) plasma nitriding by plasma diffusion treatment (PDT) and (c) deposition of TiN layer by plasma-assisted chemical vapour deposition (PACVD) additionally to PDT. Surface characterization after the different treatments showed considerable improvement in surface hardness, especially after the two nitriding processes. Moreover, the good corrosion resistance of untreated alloys was maintained. A cell culture model using human cells was chosen to study the effect of such treatments on the cytocompatibility of these materials. The results showed that Ti-5Al-2.5Fe alloy was as cytocompatible as the Ti-6Al-4V alloy and the same surface treatment led to identical biological consequences on both alloys. Nitrogen implantation did not modify at all the cellular behaviour observed on untreated samples. After the two nitriding treatments, cell proliferation and viability appeared to be significantly reduced and the scanning electron microscopy study revealed somewhat irregular surface states. However, osteoblast phenotype expression and protein synthesis capacity were not affected. PDT and PACVD may be interesting alternatives to the physical vapour deposition technique.