| Part Ⅰ:Effect of nicotine on the osseointegration of implant surface with different treatmentObjective:To study the influence mechanism by measuring the degree of intervention that nicotine effect on osseointegration and the expression of BMP-2、OPG after implantation which implant surface processed with sandblasting or acid etching.Methods:Twenty four SD rats were randomly assigned to two groups and received daily injections for 2 weeks as follows:Nicotine 2 mg/kg/bid for experimental group, saline solution for control group. Subcutaneous injected 1 mg/kg mecamylamine after 1 hour at the end of injection, and observe the nicotine withdrawal symptoms to ensure the success of the nicotine-dependence model. Then the left tibia were received the titanium implant with surface sandblasting and the right were taken surface acid etching process, which two groups with continuous nicotine-intervened. Two halves of the objects of two groups were sacrificed at the end of 2nd and 4th week respectively. And the specimens were prepared for CT, X-ray and histomorphological examinations to evaluate bone healing and were measured expression levels of bone-related genes by qRT-PCR. The data were analyzed using One-Way ANOVA test and T-test by SPSS 17.0 software package.Results:Compared with the control groups, the degree of osseointegration and the expression of OPG, BMP-2 of experimental groups were decreased significantly. Intra-group comparison, the decreased areas of low density shadow of SBI (0.74±0.12 mm2) were significantly less than AEI (1.52±0.09 mm2, P<0.05) by X-ray. The CT-BMD of SBI were decreased from 1127±28.2 HU to 960±62.2HU (P<0.05), whereas the AEI were no significant difference. Except the BMP-2 of AEI were not significantly reduced, the expression of OPG and BMP-2 were significantly decreased (P< 0.05) by qRT-PCR. The observation of histomorphological examinations were showed that the activity and quantity of osteoblast down-regulated significantly and AEI better than SBI.Conclusions;The expression of BMP-2 and OPG were down-regulated and the osseointegration around the implant were influenced by nicotine-intervened, especially for SBI.Part Ⅱ:The effect of various concentration of nicotine on the osseointagration after implantationObjective:To study the healing conditions of the soft and bone tissue around the implant and the expression of the OPG and BMP-2 under intervened by different concentration of nicotine.Methods:Twenty four SD rats were equally randomly applied for High-dose group, Middle-dose group, Low-dose group and Control group, and intervened with 2mg/kg/bid,0.2mg/kg/bid,0.02mg/kg/bid and saline for 2 weeks. Then the two tibia of the rats were implanted by the titanium implant with the surface acid-sandblasting process under continuous nicotine-intervened. The specimens were observed by X-ray、CT、qRT-PCR and SEM (scanning electron microscope) at the end of 2nd and 4th weeks. Datum analyzed with SPSS 17.0 One-Way ANOVA test and comparison in group analyzed with T test.Result:The X-ray shows that there is no significant difference in group, except the HDN and control group. The CT images and BMD show that the nicotine groups are significant lower than control group, and there is significant difference in nicotine groups. The qRT-PCR show that the expression of the BMP-2 and OPG is gradual reduced as the increasing dose of nicotine during the two weeks, but there is no difference between the LDN and the control group (1/0.93±0.17), and the genes expression of the groups are sharp reduced in the later time. The SEM shows that the trabecular bone is inhibited and the woven bone is becoming, the bone matrix is distribution and disordered arrangement as the level and the intervened time of nicotine increased.Conclusion:There is great relationship between the inhibition of osseointagration of peri-implant and the down-regulate the expression of osteoinductive activity genes, and the effect has obvious time and concentration dependence. |
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