Effects Of Low-temperature Argon Oxygen Plasma-activated Implants On The Osseointegration In Rats

Objective: As the most commonly used implant material in the oral implantology,titanium has the ability of osseointegration after implantation.Whether the implant can form good bone union with the surrounding alveolar bone after implantation is an important factor for the success of the implant operation.The purpose of this study was to activate implants by non-thermal argon oxygen plasma(NTAOP)to improve their surface energy,surface hydrophilicity,and promote the ability of osseointegration.Methods: The implants were divided into sand blasted acid-etched implants(SLA Ti)and smooth surface implants(SM Ti).Pure argon and argon +5% oxygen were used as input gas to generate non-thermal plasma,and surface activation treatment was performed on the two implants respectively.Two kinds of implants activated by non-thermal argon oxygen plasma were used as the experimental group,namely SLA Ti+ NTAOP and Sm Ti+ NTAOP.Two kinds of implants without low temperature plasma activation were set as the control group,namely Sla Ti and Sm Ti.Scanning electron microscopy(SEM)was used to observe the surface morphology of the implant before and after NTAOP treatment.X-ray photoelectron spectroscopy(XPS)was used to analyze the surface chemical composition of implants treated with NTAOP.The implants were then implanted into the rats.Sequential fluorescence labeling was administered to label bone metabolism using alizarin red and calcein on days 4 and 3 and 14 and 13 before rat execution,respectively.The rats were then executed after 4 and 8 weeks to collect the rat femur specimens containing the implants.The osseointegration of the implants was evaluated by micro-computed tomography(Micro-CT)and hard tissue sections of the rat femur were made to assess the osseointegration of the implants at the histological level.Results: After NTAOP treatment,the surface topography of the implant was not changed.The results of XPS showed that the carbon content of the surface of the implant decreased after the NTAOP treatment while the oxygen and titanium content increased.Fluorescent labeling showed that new bone was deposited earlier in the experimental group than in the control group,and deposition bands of fluorescence enrichment indicated a chronological and homogenous mineralization of newly formed bone.Microcomputed tomography showed that the percent bone volume,trabecular number and connectivity density of trabecular were higher in the experimental group than in the control group at 4and 8 weeks,and the differences were statistically significant(P<0.05).After taking photos of hard tissue sections under microscope,the software analysis results showed that the bone to implant contact rate in the experimental group was significantly better than that in the control group,and the difference was statistically significant(P<0.05).Conclusion: 1.There was no change in the surface morphology of the implant after non-thermal argon oxygen plasma activation.2.After non-thermal argon oxygen plasma activation,the content of carbon impurities on the surface of the implant decreased,and the content of oxygen functional groups increased,which improved the hydrophilicity of the surface of the implant.3.SLA Ti and SM Ti implants activated by non-thermal argon oxygen plasma can promote the early osseointegration and improve the implant-bone contact.