Study On Surface Modification And Properties Of Tooth Implant Materials

Titanium and titanium alloy, due to their desirable bio-compatibility, corrosion resisting and mechanical properties, had become the first choice of human histology substitutes and prosthetic materials at dental implanted material, dental restorative material, osseous tissue traumatic material, joint prosthesis, and so on. At the present time, numerous researchers had just focused on the study at biocompatibility, blood compatibility and tissue compatibility of biomaterial, but neglected the study of bacterial adhesion on biomaterial. It had been reported that, the invalidation of biomaterial caused mainly by biomaterial centered infection (BCI), and bacterial adhesion on biomaterial surface was the initiating factor leading to this infection. Almost all kinds of bacterium were adhesive, and could create adhesion secretion. As to tooth implant materials, the peri-implantities was a sort of BCI, and it was the main factor cause implant invalidation, which was induced by bacterial adhesion. Therefore reduce the bacterial adhesion on the surface of implant material could decrease the morbidity rate, however, could increase the mission success rate of implant manipulation.The failure forms of titanium and titanium alloy, such as wear-and-tear or corrosion, which both occurred on the surfaces, and surface modification treatment was an effective method to overcome these troubles. This paper explored to surface modify pure titanium (TA2) and titanium alloy (TC4), which were used as tooth implant materials by employing plasma nitriding and multi-arc ion plating, Ti-N modified layers and TiN coatings were formed on the surfaces of materials, the anti-bacterial adhesion property was obtained at the same time.Elements distributions and micrographs of the modified surfaces were analyzed by using Spectrum GDA750 discharge optical emission spectrometer (GDOES) and Zeiss Axiovert 25CA inverted microscope; phase compositions were characterized by D/Max 2500 X-ray diffraction spectrometer; micro-hardness values were measured by using Leco M-400-H1 hardness measuring instrument, the untreated / treated surface topographies and surface roughness were investigated by Jeol-JSM 6360LV scanning electronic microscope (SEM) and TR 240 rough-meter respectively, OLYMPUS-BX51T-32000 Fluorescence microscope and OLYMPUS-C-5060-Wide-Zoom digital camera were used to observe bacterial adhesion status on both untreated and treated surfaces and photo the fluorescence microscope images, anti-bacterial property of untreated and treated surfaces, and the diversity of the anti-bacterial property between Ti-N layers and TiN coatings were analyzed and compared by use of SPSS software, static immersion corrosion and electrochemical corrosion experiments in the artificial saliva were used to test the corrosion resisting property of the modified surfaces.The results showed that: uniform and closed modified surfaces were obtained on pure titanium (TA2) and titanium alloy (TC4) by employing plasma nitriding and multi-arc ion plating; the thickness of the nitriding layers were about 4.8μm and 6μm; the thickness of the coatings were about 3.8um and 4μm; modified surfaces had higher hardness than the substrate samples, the nitriding layers were built up by TiN, Ti₂N andα-Ti; the coatings were built up by pure TiN; both surface topographies and surface roughness had changed after surface modification, bacterial adhesion assay indicated that the population of bacterial adhesion on the modified surfaces decreased significantly, an anti-bacterial adhesion property was available; statistical evaluation showed, there was noticeable disparity between untreated and treated surfaces at anti-bacterial adhesion property, and the disparity between the surfaces, which were modified by two treatments had no statistical significance at anti-bacterial adhesion property; static immersion corrosion and electrochemical corrosion experiments in the artificial saliva showed that the corrosion resisting property of the modified surfaces had been improved to different levels.