Objective To compare the effects of different crown materials on the stress distribution of dental implants by finite ele-ment method.Methods A three-dimensional finite element model of implant-supported crown restoration of the right mandibular first molar was established.Four kinds of crown restoration materials were used,including polymer infiltrated ceramic network Vita Enamic,resin nanoceramic Lava Ultimate,zirconia ceramic Cercon,and polyether-ether-ketone breCAM.A displacement load of 0.01 mm or 200 N was applied to the occlusal surface of the right mandibular first molar,and the analysis of reaction force,the maximum variability of shape,the maximum principal stress,the maximum equivalent stress was performed.Results The results of stress analysis under 0.01 mm displacement load showed that the maximum equivalent stress of Cercon was 937.30 MPa,and that of breCAM was 67.09 MPa.The stress concentration of crowns and implants was obvious.The maximum equivalent stress of the surrounding alveolar bone of Cercon was the highest(26.61 MPa),and that of breCAM was the lowest(3.87 MPa),which was about 1/7 of that of maximum group.The stress concentration range of resin-matrix ceramics and polyether-ether-ketone was relatively small,and the distribution was more uniform.When 200 N was applied,the maximum principal stress and the maximum equivalent stress distribution of the four models were similar,and the maximum variability of shape of breCAM was larger at the loading site.Conclusion Under the same displace-ment load,the stress concentration of polyether-ether-ketone and resin-matrix ceramics crown was lower than that of zirconia.There was no significant difference in stress concentration in the implant and surrounding alveolar bone among polyetheretherketone,resin-ceramic composite,and zirconia crown restorations under the same load.Further research on long-term durability of PEEK and resin-matrix ce-ramicsis needed through practical and clinical trials.

Objective To perform a network meta-analysis (NMA) for the efficacy of 11 drugs in preventing chronic peripheral neuropathy induced by platinum and taxane (PTIPN). Methods PubMed, Cochrane library, Embase, CNKI, WanFang database and VIP database were searched up to February 2021 for relevant randomized controlled trials (RCTs) addressing the drugs to prevent PTIPN. After extracting relevant data, Stata 14.0 and ADDIS 1.16.6 softwares were used for statistical analysis. Results A total of 70 studies involving 6201 patients were included. The results of network Meta-analysis showed that amifostine, ganglioside, Huangqi Guizhi Wuwu decoction (HQGZT), vitamin E, calcium and magnesium infusion and omega-3 fatty acids were superior to placebo or blank groups in reducing the incidence of overall or severe PTIPN. The rank probability plot and the SUCRA calculation results suggested that amifostine, HQGZT and omega-3 fatty acids were in first order. The differences between the 11 drugs and placebo or blank groups were not statistically significant, except for amifostine which was reported to aggravate the adverse reactions of nausea and vomiting and hypotension in patients. Conclusion HQGZT, Ganglioside, Vitamin E, omega-3 fatty acids, calcium and magnesium infusion and glutathione can reduce the occurrence of PTIPN, and HQGZT has the highest efficiency.

Objective To explore the polymorphism of microbial community after laparoscopic abdominal exploration by using bacterial 16s ribosomal DNA (16S rDNA) sequencing technology. Methods New Zealand rabbits were divided into model group and control group. The rabbits in the model group were operated by portable laparoscopy, and the rabbits in the control group were not treated. One week later, the peritoneal effusions of the model group and the control group were taken for 16S rDNA sequencing to analyze the microbial community polymorphism. To explore the changes of microbial community in peritoneal effusion in the model group compared with the control group. Results After 16S rDNA sequencing, bioinformatics was used to determine the microbial communities. Inter group difference analysis showed a good similarity of microbial communities between the two groups. OTU taxonomic analysis and species composition analysis (Rank-Abundance curve and Venn diagram) found that the microbial community level of the model group was significantly higher than that of the control group. Alpha diversity analysis (Sobs, Ace, Shannon, Simpson) showed that the richness and diversity of microbial community in the model group were higher than those in the control group. Microbial composition analysis showed that the number of miscellaneous bacteria in the model group increased by about 30% compared with the control group. The species differences between the two groups were tested for significance. It was found that Pasteurellales, Neisseria and Tsukamurella increased significantly. Conclusion The diversity of microbial communities in peritoneal effusion increases after laparoscopic abdominal exploration in New Zealand rabbits, and the most significant increases are Pasteurella, Neisseria and Tsukamura.

AIM and METHODS: Chemotactic migration of peripheral blood mononuclear cell(PBMNC) of healthy blood donors(BD) and patients with blood stasis syndrome(BSS) across polycarbonate membrane(PCM) and human umbilical vein endothelial cell(HUVEC) monolayer, IL-8 produced by migrat PBMNC and effects of protocatechuic aldehyde(PCA) on the process mentioned above were investigated. RESULTS: 1) The numbers of migrating PBMNC in group BSS was higher than that in group BD(P