The Improved Biological Performance Of A Photo-induced, Super-hydrophilic Titanium Implant

Most implants fail because the bone-implant interface is destroyed, the osseointegrationis showing its important practical significance following the immediate implant techniquedevelop. Although lots of methods of roughness the surface have adopted for enhancingthe bone-implant integration, however, bone-implant contact area (BIC) still not ideal (justbetween30%and70%). Meanwhile, this roughness surface which could be one factorhaving an influence on the peri-implantitis controlling.Recently, similar results were reported in studies conducted by, which revealed that inthe early stage of healing, the bone-implant contact (BIC) remained less than60%for4-week-old implants, whereas this metric reached over90%for new implants. Nowadays,some researches―remaining‖the bioactivity and hydrophilic by immerging the implant inthe solution (PH=5). But this method is still oppugning.More important, the plasma protein shows negative charge in the surgical site beforeinserting the implant and the titanium surface show positive charge after processing. Thismeans in theory, there may be two different bone-implant connected style exist.Scientists have found that TiO2is also known to be an effective photocatalyzingmaterial that can be used to improve the hydrophobicity of the titanium surface. Largelevels of UV energy (greater than3.2eV) are required to induce photocatalytic activity,i.e., to excite an electron from the valence band to the conduction band, which allows for the transmission of electric current. Many studies have reported that this photocatalyticsemiconductor surface substantially strengthens osteoblast retention, an effect that wasassociated with the enhancement of intracellular structural development during celladhesion. However, the biological mechanisms by which electric charge modifications onsuper-hydrophilic surfaces enhance bone-implant integration are unclear.The objective of this study was to investigate the evidence of the―direct‖bone implantconnected and further test the effect on the photo-induced, super-hydrophilic bioactivitytitanium surface.【Methods】1.For this study,48titanium implant rods (diameter2mm, length6mm) and52disks(diameter20mm, thickness1mm) were fabricated from pure titanium grade4(Northwest Metallurgy Institute, Shann’Xi, China). The surfaces of the24testimplants were MAO treated and were randomly divided into two groups. Theimplants from both group A and group B were stored under dark conditions for8weeks following processing. Following this phase, the group B specimens werefurther UVC-treated for48h.2.We used an X-ray photoelectron spectra (XPS) system (Model PHI-5072, PhysicalElectronics Inc., China) using Mg K R radiation (250W, pass energy of29.35eV)to analyze the changes to the titanium surface following UVC irradiation.3.The52super-hydrophilicity of the disk specimens was measured by assessing thestatic contact angles using a contact angle analyzer (Face, Kyowa Interface ScienceCo. Ltd., Japan).4.The52super-hydrophilicity of the disk specimens were cultured with osteoblast (OB)to observe the different of differentiation and proliferation on the surper-hydrophilicsurface and dydrophobic surface.5.The specimens with inserted implants were examined by micro-CT scanner,histological observation, push-out test and EDS test.【Results】1. The notable differences in the intensities of the457and453.8eV Ti2p peaks between the UV-treated and un-treated groups indicated that more Ti element exposed.Furthermore, XPS analyses revealed that the intensity of carbon was decreased bynearly half on the UV-photolyzed surfaces means the contaminations are removed andthat the intensity of the O1s peak was also increased which indicate that the hydroxylradical increased.2. The initially super-hydrophilic (contact angle <10) UV-treated surfaces becamehydrophobic (contact angle>70) following7days of exposure to the atmosphere.3. No significant difference was observed in the week4group and12week group;however, the bone anchorage strength was detected in the test group (70.4±9.3N)compared to the control group (56.7±6.6N) at8weeks.4. In the bone-implant interface area, a layer of new bone was―directly‖contacted withthe implant on the UV-treated surface, on the contrast, a significant―gap‖structurewas found on the un-treated surface. The Ca, P, O and Ti element spectra line alsoindicated the bone structure was―directly‖integrated with the titanium on theUV-treated surface, however, there was an oxygen layer generally exhibited betweenthe bone and implant on the un-treated surface.5. At4weeks and12weeks, the bone volume (BV) and tissue mineral density (TMD)were slightly increased in the test group than that in control group. However, at8weeks, the UV-treated group had visually greater bone formation than that in theun-treated group in the ROI, and the BV and TMD were significantly increased in thetest group compared to the control group.6. The histological evaluation showed that the bone-implant integration in the uv-treatedsurper-hydrophilic surface group is better than the un-treated hydrophobic surfacegroup both from4week to12week.【Conclusion】1. UVC irradiation is sufficient to overcome the influence of biologicaltime-dependent degradation and to recover the hydrophobic surface tosurper-hydrophilic surface. 2. UVC irradiation can purify the titanium surface by removing the carboncontamination layer.3. XPS test showed―O‖element increased may indicate that the dydroxyl radicalincreased on the UV-treated titanium surface.4. UVC irradiation can lead potential difference increased. This notable differentelectric exchanged on super-hydrophilic titanium surface effectively increases theadhesion of the osteopontin and the osteo-conductivity.5. The surper-hydrophilic surface effect on the osseointegration in the early healingstage (8w) and this notable―direct‖bone-implant integration connective structuremay change the concept of the traditional type of osseointegration depend on theCa/P hemidesmosome connective structure.All in all, there are significant to adopt UVC induced the titanium bioactivity toenhance the osseointegration when the roughness technique, gene and biomoleculelayer by layer molecular self-assembly technique surfer the bottlenecks.