Influence Of Two Different Surface Modifications To Both Titanium And Its Alloy Implant On Bacterial Adherenc

Objective: To investigate the effect of two different surface treatments to pure titanium and its alloy discs on their surface structure and property,and on Streptococcus mutans adhesion in comparison with control surfaces of equivalent roughness.Methods: Standard-sized polished commercially pure titanium and its alloy discs respectively were randomly divided into three groups,three discs each. One group was modified using plasma nitriding technique, another was treated employing physical vapour deposition (PVD coating) with titanium nitride (TiN) technique, the remained was used as control. The observations and electron micrographies were performed with a scanning electron microscope,and estimation of surface roughness was done by a profilometer. The metallograph was viewed with Axiovert 25CA optical image analysis instrument. In addition, elements distribution variation along cross-section of surface modified layer have been studied with GDA750. Titanium and its alloy discs were incubated in the respective bacterial cell suspension for one hour and,after washings, photographed and counted the adhered bacteria which was stained with acridine orange by fluorescence microscopy.Results:⑴.The surface roughness (Ra) of all surfaces examined was similar below Ra= 0.20μm ,the so-called"threshold Ra",and two surface treatments only made the surface roughened slightly. Scanning electron microscopy proved some unevenly distributed microgrooves caused by polish was disappeared in each modified surface, showing that two surface treatments changed or covered the original texture of the surface. From the metallograp, the marked boundary was between the surface modified layer and the base layer except for nitrided titanium. The result of GDS showed that the surface modified layers were composed of titanium nitride.⑵.For commercially pure titanium, a significant reduction of the number of adherent bacteria was observed on modified titanium surfaces compared to polished titanium surfaces (p<0.001), whereas no statistical significance was found between two surface treatments (p=0.485). For titanium alloy material, two different modified surfaces also showed a significant decrease of adherent bacteria compared to polished titanium alloy surface (p=0.005,0.008), and no statistical difference was also noted between two surface treatments (p=0.866)Conclusion: The modification layers of titanium and its alloy used by plasma nitriding and PVD...