ABSTRACT
Objective To investigate the stress distributions on implant-bone interface and fatigue behaviors of biomimetic titanium implant under static and dynamic loading conditions to provide theoretical basis for a new implant which may effectively transfer the stress to surrounding bones. Methods A 3-D finite element model of a posterior mandible segment with an implant bone was constructed by a CAD (Pro/E Widefire 2.0) software. Two different implant models (a dense implant No.1 and a biomimetic implant No.2) were designed. The stress distributions on bone-implant interface under dynamic and static loading conditions were analyzed by Ansys Workbench 10.0 software, as well as the fatigue beha-vior of the biomimetic implant. Results The cervical cortical bones in the 2 implants were all high stress region under the same loading condition. The maximum von Mises stress on the interface and high-stress region in the cancellous bone region, and the maximum stress in the root region of the biomimetic implant were lower than those of the dense implant. The stress on the implant-bone interface decreased from the top to the bottom. The stress in the cervical cortical bone under the dynamic loading was 17.15% higher than that of the static loading. There was no significant difference in maximum stress at the cortical bone region between the dynamic and static loading conditions. The maximum stress of the dense implant in the cancellous bone region was 75.97% higher and that in the root region was 22.46% higher than that of the biomimetic implant. The maximum stress on the implant-bone interface was far less than the yield strength of pure titanium. The stress distribution in the cortical region of the biomimetic implant was 7.85% higher than that of the dense implant, and the maximum stress in the cortical bone was smaller than the yield stress of cortical bone. Within the dynamic loading of 50-300 N, the safety coefficient was all higher than 10, and with the increase of loading pressure, interface stress in the cancellous region increased linearly. Under the loading of 300 N in the axial and 25 N in the lingual 45°, the maximum stress was 11.38 MPa. Conclusion Biomimetic style implant can effectively transfer the implant-bone interface stress to surrounding bones in the cancellous bone and root region, and the structure with the improved design is safe under normal loading pressure.
ABSTRACT
Objective To establish the culture technology system for the in-vitro induction of adventitious buds of Sarcandra glabra(Thumb.) Nakai by investigating the induction factors of in-vitro adventitious buds.Methods Stem segments of Sarcandra glabra were cultured as explants.The effects of culture medium with different concentrations of 6-benzylaminopurine(6-BA) and indole butyric acid(IBA) added,lighting time,light intensity,and temperature on the induction of adventitious buds from the explants were observed.Results The medium containing both 6-BA and IBA was more effective to induce shoot formation of Sarcandra glabra than the medium only containing 6-BA or IBA;high concentration of plant hormones would block the growth of the plantlets.The scattering light or faint direct light was suitable for the shoot formation,while dark or strong light would induce the plantlets withered or even dead.Temperature in the range of 25 ℃～30 ℃ was beneficial for the growth of adventitious buds,and the bud induction rate arrived 100% at the temperature of 25 ℃.Conclusion At the temperature of 25 ℃,the faint sunlight or direct light less than 2000 lux,and the medium with 2.5 mg?L-1 6-BA and 0.1 mg?L-1 IBA added can stimulate significantly the adventitious bud formation of Sarcandra glabra,the induction rate up to 82.98%.
ABSTRACT
Objective To investigate the negative effect of cigaratte smoking on periodontal theraphy. Mothods 84 patients with periodontopathy were selected and divided into two groups. The smoking group (group A) included 33 patients and the non-smoking group (group B) included 51 patients. All the patients received a systematic treatment. The effects of the treatment between different groups were compared through the debris index(DI),calculus index(CI),periodotal disease index(PDI) which were respectively recorded before and after treatment.Results After the treatment the DI,CI,PDI of two groups were all decreased; wheras compared with group A, every index of group B was significantly lower. Conclusions Somking seriously influences the effect of periodontal therapy. Therefore, to give up smoking is very important for preventing and treating periodontopathy.