Why does titanium osseointegration

Meanwhile, a strong doublet peak appeared at Likewise, for sample TO-6 Fig. This result indicated the complete TiO 2 overlay on the titanium surface after thermal oxidation treatment. The EDX results are shown in Table 2. The oxygen percentage was After surface thermal oxidation treatment, oxygen significantly increased to Moreover, the oxygen content was not altered much between the TO-2 and TO-4 groups, both of which were slightly lower than the TO-6 group.

To determine the crystallinity of this titanium dioxide layer on the Ti surface, XRD analysis was performed on various samples.

The diffraction peaks of both the anatase and rutile phases became increasingly strong with a prolonged thermal oxidation period. This phenomenon was mainly due to the prolonged treatment duration of thermal oxidation of titanium substrate. In this study, the relative weight percentage of rutile in TO-2, TO-4 and TO-6 with a mixture of anatase and rutile can be roughly estimated by use of the following formula With prolonged treatment time, the W R for the TiO 2 layer increased from However, there was a slight decrease to From these data, it can be seen that the thermally oxidized titanium surfaces became more hydrophilic than the control, TO-0, especially for the TO-6 sample.

No significant differences were observed among those four groups. Cells attached to the control titanium surface spread well, whereas the thermally oxidized titanium surfaces exhibited better attachment Fig.

After 2 days of incubation, cells spread well on the thermally oxidized specimens Fig. After 7 days of culture, the cells had grown well and reached complete confluence in these four groups Fig. MTT cell metabolic activity assay Fig. No statistically significant differences were observed among the four samples on days 1, 4 or 7. The total cell metabolic activity on the control surfaces was not significantly greater or smaller than those on the thermal-oxidation-treated titanium surfaces.

The alkaline phosphatase ALP semi-quantification results are shown in Fig. After 4 and 7 days of incubation, there was no significant enhancement detected in the TO-2 or TO-4 groups compared to the control samples. The secretion of ALP was significantly improved in the TO-6 group compared to the other three groups. After 21 days of culture, as measured using Alizarin red S staining, optical images were obtained and are shown in Fig. All of the thermally oxidized titanium surfaces were stained stronger than the non-thermally treated titanium surfaces for Alizarin Red S.

In particular, the staining colour showed best in the TO-6 group. As shown in Fig. The TO-6 group exhibited the best matrix mineralization among those four titanium surfaces. The TO-2 group exhibited better matrix mineralization than the TO-4 group, although the difference was not significance.

Cells incubated on the TO-6 group exhibited the highest expression of these relatively late-stage markers. Cells cultured on the TO-2 group showed a better expression than did the TO-4 titanium surfaces. The cells seeded on the TO-2 and TO-4 groups expressed a higher level compared to the control titanium surface.

Two types of fluorochromes at 6 and 9 weeks time point were used to assess newly formed bone area. As illustrated in Fig. At different time points after implantation, the Alizarin Red S labelling area and calcein labelling area for the TO-6 titanium implant were significantly higher than those of the other three groups. The differences among the latter three groups were not significant.

The TO-4 group had less bone contact compared to the TO-2 group, but it was not a statistically significant difference. The TO-6 group had the most bone contact among these four groups. Titanium-based materials are the ultimate choice for orthopaedic implants. To meet all of the clinical needs, their biocompatibility has been explored for possible improvement. The properties of the surface oxide is an important aspect in influencing the biocompatibility of titanium Titanium oxide exists in three different crystal lattices, including anatase, rutile and brookite.

After thermal oxidation treatment, the thickness of oxide layer was significantly increased. The crystallinity of this surface TiO 2 layer was significantly changed and was composed of anatase and rutile crystal phases. It has been reported that anatase film can attract calcium and phosphate ions from the physiological environment to form an apatite coating. In contrast, the rutile film on titanium was associated not only with basic hydroxyl groups on the surface but also acidic hydroxyl groups and surface energy.

The mixture of rutile and anatase might be responsible for enhancing the osteogenic properties of this biomaterial. The existence of both anatase and rutile could help improve the osteogenic activity of titanium. In addition to surface oxide crystallinity, surface wettability is believed to be an important factor in the bioactivity of the titanium surface. The contact angles on the thermal-oxidation-treated Ti surfaces were significantly lower than on the control plate and a prolonged heat-treatment time gradually decreased the contact angle.

Surface morphology and chemical components are the two dominant factors affecting material wettability The observed enhancement in surface wettability might be partially affected by changes in titanium oxide crystallinity.

It might more likely be attributable to the gradually changing titanium nano-scaled surfaces. After etching with oxalic acid solution, the titanium surface showed a rather homogeneous micro-scaled surface. However, in the high-resolution images, particle-like oxide appeared on the ridges and valleys of the pits and holes structure, which was rather smooth in the control group. Along with the changed wettability, in our study, there were no significant differences in protein adsorption observed among the specimens.

Though the initial cell attachment observed by cytoskeleton staining showed that cells cultured on oxidized titanium surfaces seemed to spread out better than on the control group, there was no obvious difference in cell morphology among the non-oxidized titanium surface and the oxidized titanium surfaces after a short period of time, as observed in both fluorescence staining and SEM.

This phenomenon suggested that the minor difference in surface wettability in our study did not have the ability to affect protein adsorption or cell attachment. The interactions among titanium, titanium oxide, proteins and cells were complex. These changes alone or together played a positive role in promoting the osteogenic activity of the thermal-oxidation-treated titanium surfaces. However, these changed titanium surface characteristics did not have the ability to influence titanium surface protein adsorption or the cell response, including initial cell attachment, cell adhesion, or cell morphology.

Compared to control group, TO-2 and TO-4 did not significantly promote the new bone formation in vivo either. Despite the lack of a significant difference in these cell functions, including cell attachment, cell adhesion and cell morphology, both the osteogenic activity in vitro and BIC in vivo were improved. Cells cultured on the three oxidized titanium surfaces grew well and exhibited better osteogenic activity than on the control samples.

The fluorochrome labelling results at early stages of implantation could reflect the promoted new bone formation and mineralization in the TO-6 group. The in vivo bone implant contact and bone volume ratio results also showed enhanced osseointegration after several hours of oxidization.

This enhanced osteogenic activity can probably be attributed to the complex interactions among altered nano-scale titanium surface topography, changed titanium oxide crystallinity, increased oxide layer thickness and the enhanced wettability. However, it is difficult to determine how these elements interact or which element plays the most important role in this cell function enhancement.

It is interesting to note that the TO-4 group exhibited less up-regulated osteogenic activity in vitro and worse osseointegration in vivo , though non-significantly. In agreement with the cell response tendency in vitro and in vivo , it was surprising to find that the W R for the TiO 2 layer of the TO-6 group was the highest, whereas that of the TO-4 group was lower than that of the TO-2 group.

A previous study demonstrated that with the addition of rutile TiO 2 on the titanium surface, its ALP activity was increased According to our results, we hypothesize that the relative weight percentage of rutile for the TiO 2 layer might be positively correlated with the osteogenic activity and osseointegration of the titanium surface.

With regard to the enhancement effect of thermally oxidized titanium surface on the osteogenic activity, a plausible mechanism was proposed from the following two points. On the one hand, the construction of surface hierarchical structure may endow titanium surface with favorable osteogenic activity The increase in thickness of the oxide layer contributed to the enhanced osteogenic activity.

Meanwhile, the difference in oxide layer thickness between TO-6 and TO-2 or TO-4 may also account for the distinct osteogenic activity of the thermally oxidized titanium surface. This oxidation method requires neither a high reaction temperature nor complicated reaction processes. It can be used to produce micro- and nano-scale modified titanium implants with relatively long reaction times at rather low temperatures. It enhanced the osteogenic differentiation activity of rBMMSCs and improved osseointegration in vivo , thus suggesting that surface thermal oxidation could potentially be used in clinical applications to improve bone-implant integration.

Firstly, commercial pure titanium Cp-Ti, Grade 1 foils with dimensions of 1. Titanium surface was etched and homogeneous surface microstructure was obtained. Subsequently, the Ti foils were ultrasonically cleaned in deionized water and dried in ambient atmosphere for further use. After acid etching, thermal oxidation treatment was conducted on the Ti foils. Subsequently, the furnace was naturally cooled to room temperature. Meanwhile, pure medical titanium rods Grade 1 with an external diameter of 0.

The acid-etched Ti was used as the control group denoted as TO Five drops of contact angle measurements were performed for each sample. The experiment was repeated twice. After 48 hours of incubation, the medium was changed. Cells at passage 2—3 were used in the following experiments. Finally, they were mounted on glass slides and observed After 2 days of culture, cells were fixed in 2. Then, they were dehydrated by increasing concentration of ethanol.

Finally, the samples were dried by hexamethyldisilazane, sputter-coated with gold and examined by SEM For the cell proliferation assay 38 , cells were cultured on the four specimens for 1, 4 and 7 days.

The cells were cultured on the substrates for 4 and 7 days. A semi-quantitative analysis of ALP was carried out according to previously described procedures They were washed several times with distilled water and observed. Intracellular total protein content was determined by use of the microBCA protein assay kit. ALP and calcium deposition quantity analyses results were normalized to the total protein content Primer sequences for the selected genes were the same as those described in previous studies 41 , The relative expression levels for each gene of interest were normalized to that of the housekeeping gene GAPDH.

Immunofluorescent staining was carried out to detect the expression of osteocalcin protein. After washed with PBS for three times, cells were permeabilized with 0. Cellular nuclei were counterstained with DAPI. All specimens were mounted on glass slides and observed.

Four male white New Zealand rabbits with an average weight of 2. The surgery was conducted according to previously published procedures A lateral longitudinal skin incision was made to expose the mid-shaft of the femur. The elucidation of the relevant mechanism can accelerate the development of optimal surfaces.

The surface treatment techniques introduced in this review make it possible to apply metals to a scaffold in regenerative medicine or tissue engineering. The author confirms being the sole contributor of this work and has approved it for publication. The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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In addition, a low number of implants seem to be lost for primarily reasons other than biofilm-induced infection.