Objective To investigate the damage characteristics of peri-implant bones with varying densities under impact and occlusal forces using numerical simulation.Methods A finite element model of the microstructure of an implant and bones with different densities was established.Impact and occlusal forces were applied sequentially to the implant.A user material subroutine was created for failure judgment using stress-based failure criteria,enabling the analysis of bone damage caused by impact and occlusal forces.Results No cortical bone damage was observed in bones of varying densities under impact force.Damage primarily occurred in the trabecular bone at the base of the implant,with the extent of damage worsening as bone density decreased.Additionally,the number of failed bone elements generated by the damage increased with reduced bone density.Bone tissues with pre-existing impact damage sustained secondary damage when subjected to occlusal force:the bonding interface between the implant and cortical bone was damaged,leading to implant displacement and fracture of peri-implant trabecular bone.The damage caused by occlusal force also worsened as bone density decreased.Conclusions The degree of damage from impact and occlusal forces is correlated with bone density,with damage worsening as bone density decreases.This underscores the protective role of cortical bone.The application of occlusal force exacerbates bone tissue damage,leading to implant displacement when the cortical bone is damaged.In clinical practice,patients with a history of impact damage should undergo thorough examination and evaluation.The occlusal force borne by damaged bones should be reduced;if necessary,the implant should be removed and reinserted after re-establishment of osseointegration.

Objective To investigate the damage characteristics of peri-implant bones with varying densities under impact and occlusal forces using numerical simulation.Methods A finite element model of the microstructure of an implant and bones with different densities was established.Impact and occlusal forces were applied sequentially to the implant.A user material subroutine was created for failure judgment using stress-based failure criteria,enabling the analysis of bone damage caused by impact and occlusal forces.Results No cortical bone damage was observed in bones of varying densities under impact force.Damage primarily occurred in the trabecular bone at the base of the implant,with the extent of damage worsening as bone density decreased.Additionally,the number of failed bone elements generated by the damage increased with reduced bone density.Bone tissues with pre-existing impact damage sustained secondary damage when subjected to occlusal force:the bonding interface between the implant and cortical bone was damaged,leading to implant displacement and fracture of peri-implant trabecular bone.The damage caused by occlusal force also worsened as bone density decreased.Conclusions The degree of damage from impact and occlusal forces is correlated with bone density,with damage worsening as bone density decreases.This underscores the protective role of cortical bone.The application of occlusal force exacerbates bone tissue damage,leading to implant displacement when the cortical bone is damaged.In clinical practice,patients with a history of impact damage should undergo thorough examination and evaluation.The occlusal force borne by damaged bones should be reduced;if necessary,the implant should be removed and reinserted after re-establishment of osseointegration.

Objective To investigate the dynamic mechanical responses and damage characteristics of peri-implant bone structures subjected to impact load.Methods A finite element model of the peri-implant bone microstructure was established,and an initial velocity was applied to the rigid body to simulate the impact load.A stress failure criterion was employed and a user-material subroutine was developed to assess failure.Subsequently,bone damage after the impact load was analyzed according to the material subroutine.Results After the impact load,the stress on the cortical bone increased rapidly,reaching a peak value(16.01 MPa)immediately.In contrast,the stress on the trabecular bone at the bottom of the implant reached its peak value(5.85 MPa)at 0.1 μs.The impact load resulted in stress waves that propagated and diffused within the bone structure,causing changes in the bone structure damage over time.The generated impact energy could be absorbed and dissipated by the trabecular bone through deformation.The deformed trabecular bone experienced damage and failure upon reaching the yield limit,whereas the cortical bone did not experience damage or failure under an impact load.Conclusions Structural changes in the trabecular bone should be considered in patients with impact damage.The numerical model established in this study can effectively predict bone impact damage by combining the structural mechanical properties and geometric characteristics of the bones.These findings can serve as a reference for assessing bone damage and post-damage treatment in patients subjected to impact loads in clinical practice.

Abstract OBJECTIVE To optimize the extraction process of Guiqi Yiyuan decoction and establish its quality control method. METHODS L9(34) orthogonal test was used to optimize the extraction process of Guiqi Yiyuan decoction by using index as comprehensive evaluation of the extraction rate, total polysaccharide content and n-butanol extract content. Thin layer chromatography(TLC) was used to identify Astragali Radix, Angelicae Sinensis Radix, Lycii Fructus and Ginseng Radix et Rhizoma in the decoction. The content of glucoside of calycosin as the main active ingredient of Astragali Radix was determined by HPLC. The differences in relative density, insoluble matter and loading amount were checked according to the Chinese Pharmacopoeia 2020 edition, and the quality control method was established. RESULTS The optimum process was 12 times water, 4 h extraction time and 2 times extraction. TLC identification results showed that the chromatograms had clear spots, good separation and strong specificity. The linear range of calycosin glucoside was 0.089 6-1.344 0 µg(r2=0.999 4), the average recovery was 99.51%, RSD was 2.59%(n=9). The relative density of decoction was 1.39, and the difference of insoluble matter and loading amount was in accordance with the provisions of Chinese Pharmacopoeia 2020 edition. CONCLUSION The optimized water extraction process is scientific and reasonable, and the quality standard is effective and controllable, which can be used for the quality control of Guiqi Yiyuan decoction.

To evaluate immune efficacy of the recombinant Lactobacillus casei, we constructed pLA-Newcastle disease virus (NDV)-F/L. casei and obtained the expression products. PCR amplified the NDV F gene carrying part of the major epitopes. The target gene was inserted to the shuttle plasmid pLA, and then transformed into Escherichia coli BL21 (DE3) in order to screen positive recombinant plasmid. The positive recombinant plasmid was transformed into L. casei by electroporation to construct pLA-NDV-F/L. casei. The positive strains were identified by PCR. The reactivity of the recombinant bacteria was identified by Western blotting and the protein expression was detected by indirect immunofluorescence, flow cytometry and laser confocal microscopy. The 14-day-old chickens in each group were vaccinated by oral plus nose drops. The pLA-NDV-F/L. casei twice immunization group and three times immunization group, the commercial vaccine group, the pLA/L. casei group, the unchallenge PBS and the challenge PBS group were established. IgG in serum and sIgA in the lavage fluid of intestinal, nasal and lung were detected by ELISA. The protection rate of chickens was evaluated. The results showed that 94.10% of the recombinant bacteria expressed the F protein. The recombinant protein was highly expressed on the surface of L. casei with a protein size of 62 kDa, which specifically bound to anti-NDV serum. The levels of anti-F IgG and sIgA antibodies in each test group were significantly higher than those in the control groups. The duration of antibody in the pLA-NDV-F/L. casei three-time immunization group lasted 28 days longer than that in the twice immunized group, and there was no significant difference between antibody peak values. The attack protection rates in each group of immunized pLA-NDV-F/L. casei three times, twice, attenuated vaccine, pLA/L. casei and PBS were 80%, 80%, 90%, 0% and 0%, respectively. Therefore, the antigenic protein of NDV F was successfully expressed by L. casei expression system, which has of reactogenicity and immunogenicity, and could induce protective immune responses in chickens.
Animals ; Antibodies, Viral ; Chickens ; Immunization ; Lactobacillus casei ; Newcastle disease virus ; Vaccines, Attenuated ; Viral Vaccines