| Background:The dental implant widely used in clinical application, mechanical properties of porous titanium were reduced and close to that of bone tissue, and can effectively reduce the stress shielding effect, suitable pore size structure could provide space for new bone ingrowth, and internal pore were beneficial for vascularization and metabolic substance transport. Using 3D printing technology can produce porous titanium specimens with high precision. Chitosan/hydroxyapatite composite coating is with fine biological compatibility and micro-rough surface, when combined with porous Titanium implant could enhance osseointegration rate and stability.Purposes:To analyze mechanical properties and biological compatibility of 3D printing porous Ti implant, and to investigate the promotion of osseointegration by porous titanium implant combined with chitosan/hydroxyapatite composite coating, so to provide new ideas to improve the clinical implant success rate and extend service life of oral implant.Methods:1.3D modeling software was used for the design of different porous specimens, and selective laser sintering was used for production of long strip, disc and thread-implant Ti6Al4V specimens;2. Three-point bending test was to detect the Quasi-elastic gradient of the strip specimen with different porosity (solid, P=30%,40%,50%,60%,70%);3. The disc shaped Ti6A14V specimens were divided into 6 groups:solid group, solid coating group, P=30% group, P=30% coating group, P=50% group, and P=50% coating group. MC3T3-E1 cells were cultured in porous Ti6A14V disc, and then analyze their biological properties in vitro by live & dead viability cell staining method, MTT staining, and alkaline phosphatase levels detection;4. The thread implant specimens were divided into solid group and porous group, implantation in femoral condyle of New Zealand rabbits were operated, then separate bone tissues femoral condyle from for X-ray inspection and hard tissue sections respectively in 4 weeks,12 weeks, to observe and analyze the biological properties.Results:1. Porous Ti6A14V specimens produced by SLS had regular shape and with natural micro-roughness, uniform pore-size with internal linking. Scanning electron microscopy used for topography observation, showed that titanium powder particles attach to internal surface of pores, and HA/CS coating evenly distributed with dense lamellar, less crack.2. Three-point bending tests showed that Quasi-elastic gradient of porous specimens decreased with the increase of its porosity, and the Quasi-elastic gradient were close to cortical and cancellous bone when the porosity is 30% and 70%.3. Live/dead cell viability assay showed that all cells had high viability, the percentages of live cells were higher than 85%, cell density reached more than 90% after 7 days. The MTT assay results showed that MTT value of cells on porous specimen were higher than that of solid titanium plate (P< 0.05), CS/HA coating groups were generally higher than the non-treatment groups (P< 0.05). Two groups with different porosity has no significant difference at 2 days of cell culture (P> 0.05), while the P=50% CS/HA group was higher than P=30% CS/HA group (P< 0.05) in 5 days. The ALP level of porous groups were higher (P< 0.05) than that of solid group, and ALP level of CS/HA coating groups were higher than that of control groups (P< 0.05).4. X-ray examination of femoral bone tissue showed that the implanted angle is positive, and the healing was fine, no fracture or fractures been seen. Observation under microscope of hard tissue sections showed osseointegration interface is clear and no inflammatory cell infiltration. In 4 weeks, solid implant neck and bottom had new bone cover the threads; the new bone trabecular was more elongated and with brighter and deeper red dyed compared with original bone tissue, and large number of deep dyed bone cells around the new bone. In porous titanium implant, new bone could be seen in internal pores, closely connected to implant inner surface. In 12 weeks, new bone developed from two ends to the center, and new bone was coarser and the thickness is about 450um. New bone in porous implants expanding and had trend to connect together, and it showed that large pores near the surface filled with more new bone tissue, and no inflammatory cell infiltration detected under high power lens.Conclusion:1. Preparation of porous Ti6A14V specimens could be well accomplished by selective laser sintering technology, and Ti based CS/HA coating prepared by electrochemical deposition appeared uniform and dense.2. The Quasi-elastic gradient of the porous titanium decreases with the increase of the porosity, and came close to the cortical bone and cancellous bone when the porosity is 30% and 70%, which could effectively reduce the stress shielding phenomenon.3. Porous Ti6A14V specimens produced by selective laser sintering had no cytotoxicity, porous titanium combined with CS/HA coating was more conducive to osteoblast proliferation and differentiation.4. Porous Ti6A14V implants produced by selective laser sintering with CS/HA coating had good biocompatibility, and was effective for promoting the formation of new bone in vivo. |
PDF Full Text Request