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Objective To evaluate the implant-bone interfaces on implants with active Zn coating in a rabbit model.Methods Pure titanium cylinder implants,fabricated by machining,were prepared by surface microarc oxidation (MAO).The MAO-Zn/Ca/P coated (experimental group) and the MAO-Ca/P coated (control group)implants were randomly placed in the rabbit mandible.The samples were harvested at 4 and 12 weeks postoperatively,histological analysis on the implant-bone interfaces of the two implants was performed,and the bone coverage was compared.Results The coatings of MAO presented micro-porous structure with dense and uniform features,in which size of micro-porous increased with zinc element.The histological examination of implant-bone contact interfaces showed that the bone tissues attached on the coatings increased with time.Further,the adhered bone tissue in the experimental group was thicker and denser and had a larger amount compared to that in the control group at 4 and 12 weeks postoperatively.The bone coverage in the experimental group (70.8％±13.6％) at 12 weeks postoperatively was significantly higher than that in the control group (55.9％±13.8％) (P＜0.05).The results of bone interface element showed that the apatite layer was precipitated at 12 weeks.Conclusion The addition of active zinc element can improve the biological activity of the coating,enhance the osteogenesis ability of the coating,and accelerate the osseointegration of implant-bone interfaces.
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PURPOSE: The purpose of this study was to analyze temperature change along the implant-bone interface induced by grinding the occlusal surface of implant gold prosthesis and to compare the temperature generated by grinding of prosthesis with different cooling methods. MATERIALS AND METHODS: The experimental gold prostheses were fabricated with dental gold alloy and castable abutment. The prostheses had 3 cylindrical protrusions on the occlusal surface with 1mm in height. Temperature was measured using 16 thermocouple wires attached to the implant fixture surface and the fixture was embedded in an acrylic resin block inside the 37degrees C water bath. Cylinders were grinded for a period of 30 second with a low-speed handpiece with green stone point. One cylindrical protrusion was grinded without cooling, the second one was grinded with air blow, and the third one was grinded with water-spray. RESULTS: The mean maximum temperature was measured more than 47degrees C of the implant and the maximum temperature was measured at the cervical portion of the implant in the group without cooling. There was statistically significant difference between the group without cooling and the groups with cooling (P.05). CONCLUSION: The results of this study support that the grinding of implant gold prosthesis without cooling may damage the peri-implant tissue. The continuous use of air blow and water-spray adjacent to prosthesis during the grinding of implant gold prosthesis may prove to be beneficial for cooling of the implant.
Subject(s)
Alloys , Baths , Hot Temperature , Prostheses and ImplantsABSTRACT
Objective:To investigate the effects of different impl an t diameter on stress distribution in implant bone interface. Method: The stress and strain in implant bone interface for implants with di fferent diameter (3.0 mm,3.75 mm and 5.0 mm), and with 1.47 N loading mesiodist ally were analyzed by 3 dimesion finite element analysis method. Re sults:The Von mises stress (MPa)at cervix of the implants with the diameter (mm) of 3.0, 3.75 and 5.0 were 0.807,0.533 and 1.080;the alveolar bone displacement (?m) at the cervix of the implants 0.232,0.163 and,0.111 respe ctively. Conclusion: The implant with 3.75 mm diameter is more suitable for orthodontic anchorage.
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Objective: To study the implant-bone interface remodelin g after loading of submerged and nonsubmerged implant denture.Methods: 8 adult beagle dogs were used to build the animal model. Submerged and nons ubmerged implants were implanted into the bilateral mandible. Fixed metal full c rown was used to carry out the submerged and nonsubmerged implant denture. The b eagle dogs were sacrificed by steps after loading of the dentures. HE staining t echnique was used to observe the dynamic remodeling process of implant-bone int erface.Results:2 weeks after loading of implant denture, a major ity of the implant surface attached to bone tissue directly, however, at the int erface, especially at the top of the screw thread, bone tissues were absorbed an d substituted by fibrous tissues. 4 weeks after loading, fine attachment was fou nd at the implant-bone interface and the previouly observed fibrous tissue at t he interface was gradually remodeled to form new bone. 8 weeks after loading, i mplant directly attached to bone tissues by osteo-interface, and the cellular c omponents and capillaries were decreased at the interface.12 weeks after loading , all implants attached to bone tissues by osteo-interface with high combinatio n level, typical Havers system was observed at the interface.No obvious differen ce in the interface remodeling was observed between the submerged and nonsubmerg ed implant denture. Conclusion:There is no distinct difference i n the implant-bone interface remodeling after the loading of submerged and nons ubmerged implant denture.
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Various methods and graft materials have been used to fill in the defect adjacent to the implants and considered as clinically acceptable. But it is not clear whether the regenerated bone increases the implant-bone contact and supports the implant. The purpose of this study is to evaluate regenerated bone surrounding implants using bone morphogenetic protein(BMP) and demineralized freeze-dried bone(DFDB), and the interfaces between implants and regenerated bone. bBMP was extracted and partially purified from the bovine bone matrix using heparine chromatography. Demineralized freeze-dried bone was made from the dog. Inactive insoluble collagenous bone matrix(IBM) of dog was used as carrier of bBMP. Interfaces of titanium coated epoxy resin implants were processed for demineralized section for transmission electron microscopy(TEM) and those of screw type implants were for nondemineralized section for light and fluoromicroscopic examination. Implants were inserted in the inferior border of mandible of adult dogs and artificial bony defects (3x3x4mm) were made at the mesial and distal side of implants. Defects were filled with BMP(BMP group) and DFDB(DFDB group). For the fluoromicroscopic examination, the fluorescent dyes (oxytetracycline, calcein green, alizarin red) were injected 2, 4, 6, 8, 12 weeks after implantation. The experimental animals were sacrificed at the 6th and the 12th week and their mandible were extirpated and processed for examination with light microscopy, fluoromicroscopy and TEM. The obtained results were as follows : 1. By the light microscopic findings, the defects were filled with woven bone at the 6th week and compact bone at the 12th week, and the osseointegrations were seen in both groups. There was no histological difference between them. 2. On the basis of the histomorphometric analysis, BMP group (6th week: 40.25%, 12th week: 56.04%) had higher bony contact ratio than DFDB group (38.37%, 42.63%). There was significant difference between two groups at the 12th week (P<0.05). 3. The amount of bone formation in BMP group was more prominent than in DFDB group. Significant difference was noted among two groups at the 6th and the 8th week (P<0.05). 4. By the transmission electron microscopic findings, 0.4-2micrometer soft tissue layer was found in adjacent to the interfaces and over the collagen fibrils of bone at the 6th week. However, about 100nm amorphous layer was noted at the interface or collagen fibrils directly extended to the titanium surface at the 12th week. There was no significant difference between two groups. 5. These results suggest that BMP and DFDB can be used as good graft materials in the regeneration of bone adjacent to implant, and BMP is more valuable as a bone inducer than DFDB.