| 摘要: | BACKGROUND: Titanium implants are extensively used all over the world to replace single or multiple missing teeth. The success of implant was defined and accessed by many specific criteria such as survival rate, infection and other complications. When there is insufficient osseointegration after implant placement, primary implant failure can occur. Thus, modifications of implant surface are required as to increase the early osseointegration process. As the surface modification enhances the biological response in the osseointegration, different methods of modification were performed. Currently, acid etching method is the most widely used in the current dental implants. Chemical method like acid etching is commonly investigated at high temperature but room temperature etching is less evaluated. Magnesium (Mg) is the fourth abundant essential trace element in the human body. Implant surface modification with Mg ions can cooperate as a divalent cation in the initial cellular activities of bone formation which will promote the early osseointegration and osteoblastic differentiation. Since the hydrothermal treatment is simple, environmentally friendly, inexpensive procedure and available for mass production, hydrothermal was used to precipitate Mg on the nanoscale roughened titanium surface to promote the early osseointegration.
OBJECTIVE OF THE STUDY: To promote the osseointegration in the Mg coated room temperature acid etched titanium implant surface.
MATERIALS AND METHODS: Ti disk (10mm diameter and 1mm thickness) was treated with 75% ethanol and ddH2O. Three types of acid solution were prepared for the acid etching step; (1) 37% HCl (TC), (2) 48% H2SO4 (TS), (3) mixture (1:1) of 5.80mol/L HCl and 8.96 mol/L H2SO4 (TH). The discs were etched for five different time points; 30min, 3hr, 8hr, 12hr, 24hr. After acid etching, four different level of molarity concentrations of magnesium acetate solution were used (0.4M, 0.5M, 0.7M and 1M) to coat Mg hydrothermally. The hydrothermal treatment was done for 3 hr and 6 hr. Analysis for the physical properties was done such as optical image, SEM and EDS analysis. 13 groups including the 1 control, 3 acid etched, 9 Mg coated groups were further analyzed their physical properties using XRD and XPS analysis, FTIR, wettability test and roughness analysis. Biological properties of samples were analyzed with cell attachment and cell proliferation analysis.
RESULTS: Generally, all of the groups transformed the color from lustering grey into black or dull grey at 24 h etching. The color TC group started from the 3 h to 24 h, with the increasing of the density of black color. When the etched duration was increased, the topography of the surface was transformed into crater like depression in the TC5 group. However, the surface feature of the TS and TH group only altered when the etched duration reached at 24 h. According to the data of SEM and EDS analysis, the TC5, TS5 and TH5 were showed the most significant changes in surface morphology and elemental composition after acid etching. Thus, these three groups are dedicated for the next analysis and further Mg coating procedure. After depositing Mg hydrothermally, the color of the sample transformed yellowish/gold color with the increase of the Mg acetate solution, in both 3 h and 6 h group, but the 6 h group showed the intense yellow color. A layer of Mg coating was found in the form of muddy pattern in SEM images. The surface of 3 h treated Mg coated samples had more rutile TiO2 than 6 h samples. FTIR analysis showed Mg coated sample showed more alkene functional group in Mg coated samples. Surface roughness of acid etched and Mg coated samples observed higher value than that of control group. Cell attachment on the TC5M4-2 showed the greatest and cell proliferation rate is relatively in TC5M3-2 group.
CONCLUSION: Within the limitation of current study, the TC5, TS5 and TH5 were showed the greatest surface modification after acid etching at room temperature. Mg coated samples have super-hydrophilicity properties, more functional groups, high surface roughness and high cell proliferation rate. TC5M1-1 showed the greatest physical properties and TC5M4-2 had positive biological responses. Thus, Mg coated room temperature etched Ti surface had the better physical and biological properties because they have nanoscale level surface modification, deeply seeded Mg ion, thick TiO2 layer, better initial cell attachment and higher cell proliferation rate. Thus, Mg coated acid etched Ti surface may be useful in the biomedical application. Cells mineralization analysis, osteogenic related genes expression analysis and in vivo animal study should perform in the future.
Keywords: surface modification, magnesium, hydrothermal treatment, acid etching, osseointegration, dental implant |
