Effect Of Estrogen Replacement On Bone Around Titanium Implants In Ovariectomized Rats Exposed Cigarette Smoke Inhalation

Objective:The aim of this study was to evaluate the effect of estrogen replacement on bone around implants in smoking and ovariectomized rats. It gave post-menopause and smoking women who would accept oral implant some instruction.Methods:Fifty female SD rats were randomly divided into5groups (n=10):sham-operated group, ovariectomized group(OVX), ovariectomized and smoking group(OVX+S), ovariectomized, smoking and estrogen group (OVX+S+E).The OVX+S and OVX+S+E groups were send to cigarette smoke inhalation for28weeks. All animals were submitted to sham surgery or ovariectomy according to their designations in the fifth week. Screw-type titanium implants were placed in right tibiae of rats12weeks after ovariectomy or sham surgery, then OVX+S+E and OVX+E groups were injected Estradiol Benzoate intramuscularly. Before sacrificed, bone mineral density of lumbar, tibiae and around of bone-implant was performed by dual-energy X-ray absorptiometry, then weight, kill animal, segregate, weight uterus, calculate uterus coefficient. Two specimens with implant in each group were randomly processed for SEM (scanning electron microscopic) and hand-mill piece of bone implant. The specimens for SEM were washed in saline, and cut longitudinally by slow drill to display implant-bone interface, then dehydration, evaporation and spray gold processing, implant osseointegration and changes in trabecular bone structure were captured in SEM. Seven tibias with implant in each group were processed for torque test. Then all specimens were send to decalcify with15%EDTA-2Na for6weeks, remove implants, repair tissue and make paraffin-embedded sections. With the experimental data (x±s) indication, statistical analysis was performed using SPSS13.0software package for one-way ANOVA. The results are statistically significant based on p<0.05.Results:1. The results of bone mineral density measurement demonstrated that estrogen could raise the BMD of OVX+E group’s every interesting point, compared with Sham group, p<0.05. The value of OVX+S is lower than OVX+S+E group,p<0.05.2. The body weight value of OVX group was higher than other groups, p<0.05, there was not significant about weight between sham group and OVX+S group. The uterus coefficient of OVX group and OVX+S group were lower than other groups, p<0.05.3. The observation of morphology displayed that estrogen could improve the quality of OVX+E group rat’s bone around implant. In the OVX+S+E group, it could increase the thick of bone palate around implant and improve the bone quality.4. Torque test results:estrogen could raise the torque value of OVX+E group. The value of OVX+S+E is higher than OVX+S group, p<0.05. It indicated that in some degree estrogen could improve the implant’s ability against torque.Conclusion:1. It was successful that the model making of ovariectomied rats exposed cigarette smoke inhalation and implant Titanium screw. The model was useful for continue experiments.2. Estrogen was efficient to restore BMD of rat systematical bone and improve the bone quality around implant and osseointegration.3. There wasn’t clear change about bone in OVX+S group compared with OVX group.4. In some degree estrogen could improve BMD of systematical and periphery bone-implants in smoking and ovariectomized rats. It was benefit for implant against the torque.