BACKGROUND: Trabecular metal has been reported to provide enough physiologic support for new bone formation, to induce bone ingrowth and osseointegration so as to achieve the biological synosteosis; therefore, it is available for improving the initial and second stability of the dental implant.OBJECTIVE: To explore the stress distributional differences between porous tantalum trabecular metal (PTTM) dental implant and conventional titanium (TI) dental implant in the zone of mandibular premolar using three-dimensional finite element analysis.METHODS: Three-dimensional finite element models emulating PTTM and TI dental implants were established using Mimics16.0 and CATIA in the zone of mandibular premolar with three types of bone (II, III, IV). Then 100 N force was applied on the abutment at a 45° angle to the vertical axis of the implants in software of MSC Patran2010 and Nastran2010, then the representative von Mises stress nodes were calculated and sampled randomly, and finally the von Mises stress distributional differences between two types of implants were analyzed using SPSS 20.0 statistical software.RESULTS AND CONCLUSION: (1) The Von Mises stresses around the two types of implants both focused on the interface of the cortical bone-abutment-implant region, and the stress was relatively less for the corresponding trabecular bone. (2) If the bone quality was similar, the average von Mises stress of PTTM was higher than that of TI dental implants, but there was no significant difference (P > 0.05). As the bone density lowered (II-IV), the average Von Mises stresses were both increased, and the increasing rate of PTTM was higher than that of TI in bone of II-III, and was lower than that of TI in bone of III-IV. In this experiment, there were no significant stress distributional differences between PTTM and TI dental implant. However, with the bone density reduction, the increasing rate of average Von Mises stress for PTTM was lowered than that for TI dental implants in bone of III-IV, which suggests that PTTM dental implant may be more beneficial for the primary and secondary stability in osteoporosis patients undergoing dental implantation.

Objective To evaluate the effects of gender and age on median-effective target plasma concentration(EC50)of propofol administered by target controlled infusion(TCI)causing respiratory depression.Methods Eighty ASA Ⅰ or Ⅱ patients aged 40-79 yr,with body mass index 18-25 kg/m2.undergoing general anesthesia were divided into 4 groups(n=20 each):1 middle-aged male group(MA);Ⅱ middle-aged female group(FA);Ⅲold male group(MO) and Ⅳo ld female group(FO).No premedication was administered.Propofol Was administered by TCI for 15 min,using TCI system incorporating Marsh pharmacokinetic model.EC50 Was determined by up-end-down sequential trial.The target plasma concentration(Cr)was set at 3.1μg/ml in the first Patient in each group.Each time Cr increased/decreased by 10%in the next patient depending on whether or not the respiratory depression occurred.Respiratory depression was defined as RR<8 bpm,Vr≤5 ml/kg,end-tidal PCO2≥50 mm Hg,SaO2≤94%and/or apnea≥15s.Results The EC50 and 95%confidence interval of propofol TCI causing respiratory depression were 6.40(6.09-6.72)μg/ml in group MA,5.93(5.54-6.34)μg/ml group FA,4.58(4.32-4.91)μg/ml in group MO and 4.37(4.14-4.61)μg/ml in group FO.EC50 was significantly lower in group FO than in group FA and in group MO than in group MA,but there Was no significant difference in EC50 between group MA and group FA or between group MO and FO. Conclusion The potency of propofol given by TCI causing respiratory depression is increased in the old patients as compared with the middle-aged patients and is not related to sex.

Objective To evaluate the reliability of autologous blood withdrawal during cesarean section. Methods Fifteen patients preoperatively diagnosed with pernicious placenta previa and∕or accrete by using ultrasound and magnetic resonance imaging, aged 20-35 yr, weighing 55-75 kg, at≥36 weeks of gestation, were enrolled in the study. Blood containing amniotic fluid from the surgical field was collected, and the washed blood was processed using cell?salvage machine and then filtered using a leukocyte depletion filter during cesarean section. The 20 ml blood samples collected included maternal central venous blood after delivery of fetus, unwashed blood, washed blood and filtered blood. The fetal squamous cells were counted using papanicolaou staining. The concentrations of a?fetoprotein, tissue factor, endothelin?1 and histamine were measured by enzyme linked immunosorbent assay. The fetal red blood cells were counted using the acid elution method and HE staining. Results Compared with unwashed samples, the tissue factor concentrations were significantly increased, and the fetal squamous cell count, concentrations of a?fetoprotein and endothelial?1, and fetal red blood cells were decreased in the washed samples. Compared with washed samples, the fetal squamous cell count, concentrations of a?fetoprotein and fetal red blood cells were significantly decreased in filtered samples. Compared with maternal venous blood samples, the tissue factor concentrations were significantly increased, and the fetal squamous cell count and concentrations of a?fetoprotein and endothelial?1 were decreased in filtered samples. Conclusion Autologous blood withdrawn during cesarean section can be used for reinfusion in cesarean section.