| Suitable implant-soft tissue interface can be a primary barrier to block bacteria andother inflammatory agents’ invasion, it also play an important role for long-termmaintenance of stability after implantation. According to the previous studies, TiO2nanotube from titanium implant surfaces can promote human gingival fibroblast’sadhesion and proliferation[1][2].However, nanotubes with different diameters bring differenteffects to fibroblasts[3]. Our team’s previous study shows that small diameter nanotubeeven inhibits fibroblasts’ function. Besides, different types of cells also get differentbiological behaviors when they attach to the surface of the implant modified withnanotube. Peri-implant soft tissue comprises epithelial tissue and connective tissue，eachlayer include multiple cell types. Furthermore, the influence of nanostructure of implantsurface on soft tissue healing needs further study because of the different cell survivalenvironments in vivo and in vitro. In my study, I’d like to show the influence of differentdiameters nanotubes on soft tissue healing from canine soft tissue models, and provide some theoretical basis to improve the design of dental implant surface.MethodsIn my research, TiO2nanotubes with different diameters were fabricated on polishedpure titanium implants(PT) by anodization at5V,20V and25V (NT-5, NT-20, NT-25)with PT as contro1．The surface morphology was observed by field emission scanningelectron microscope(FE－SEM). The surface roughness of samples was measured bythree-dimensional morphology measurement instrument. Contract angle was measuredwith deionized water, methyl iodide and formamide respectively. Interface energy wascalculated according to the contract angle data. Then, the implants were implanted intobilateral mandibular of4dogs. One of them was sacrificed respectively on1d，7d，14d and28d after implantation. Further, the tissue adhered to the implant surface was observed byFE-SEM. Implant-soft tissue gap was measured by superhard biopsy. The healinginterface between implants and soft tissue was observed by HE staining. The expression ofFGF-2, COL-1and EGF mRNA of the peri-implant soft tissue were measured by RT-PCR.FN secretion was observed by immunofluorescent staining. All these methods were usedto evaluate the degree of the peri-implant tissue healing.Results1. Anodization at5V,20V,25V produced30nm,100nm and130nm nanotubecoating on the titanium implant surface. With the increasing of voltage, the nanotubediameter enlarged，the thickness of nanotube wall increased，the gap between nanotubewalls increased．2. Roughest group was polished group which was measured by three-dimensionalmorphology measurement instrument, and with the increasing of nanotube diameter, therough level increased.3. Compared to the polished group, the contract angle of the nanotube groups gotsmaller. With the increasing of nanotube diameter, the contract angle became smaller, theinterface energy and wettability increased. 4. The tissue adhered to the implant surface was observed by FE-SEM, PT cellmorphology was the best, NT-5tissue adhesion was the least, NT-20single cell adhesionwas the most and NT-25matrix secretion was the most. As time goes by, cell adhesion canbe seen less and tissue adhesion got more and more.5. The implant-soft tissue gap measured by superhard biopsy observed byStereoMicroscope suggested that the implant-soft tissue gap of the biggest diameternanotube, NT-25group, disappeared at first, then NT-20group.6. HE staining showed that large diameter groups such as NT-25and NT-20gotbetter performance of soft tissue healing than PT group, and the biggest diameter groupNT-25had a even better performance than any other groups. However, there was nodifference between PT group and small diameter group NT-5.7. The RT-PCR results of the expression of FGF-2, COL-1and EGF mRNA of theperi-implant soft tissue showed that large diameter groups such NT-25and NT-20weremore active in FGF-2mRNA expression at the early stage of soft tissue healing, andNT-25group was even more than NT-20group. Small diameter group appeared inhibitionof expression compare with PT group in the early. COL-1mRNA expression at theperi-implant soft tissue increased along with the diameter of the nanotube increased, thelarge diameter NT-20and NT-25expressed more than PT, but small diameter group NT-5expressed less than PT. EGF mRNA expression increased along with the diameter of thenanotube increased at the early stage, and all the nanotube treated groups expressed morethat PT. But from14th day, the small diameter group NT-5’s expression got a significantlyincreasing and the big diameter group NT-20and NT-25began to express a little bit short.8. Immunofluorescence staining showed that FN was mainly located at peri-implantsoft tissue surface, descending from the soft tissue edge inward. FN content increased atthe peri-implant soft tissue with nanotube diameter increasing, gradually accumulated astime goes by. Furthermore, the largest diameter group NT-25secreted the highest level ofFN at the early stage. Compared with PT control, NT-20had no obvious advantage andNT-5even got a slightly inhibition. ConclusionAnodized titanium implant surface can make a uniform diameter TiO2nanotubestructure and the diameter can be controlled by voltage. The physicochemical properties ofnano-implant surface have changed, the surface wettability increases along with roughnessreducing. The result of in vivo research confirmed the large diameter nanotube surfacecould promote early peri-implant soft tissue repair and regeneration. Titanium implantsurface modified with TiO2nanotube will be used clinically by further confirmation of themost suitable nanotube diameter and improvement of the nanotube coating method. |
PDF Full Text Request