ABSTRACT
Objective To design two kinds of fixed full-arch implant-supported prosthesis and to investigate their stress distribution in the different vertical heights of the edentulous mandible. Methods The cone-beam computed tomography (CBCT) scan data of the upper denture andmandible were collected to establish the base models of the mandible. The vertical heights of the mandible models were loweredby 0. 5. 10 and 15 mm. and the three-dimensional finite element models of implants with different vertical heights supported by mental foramen 6 parallel implants and supported by “All-on-Four” were established. including 2 groups (8 models); 6-implant group and 4-implant group. A 250 N vertical force was applied to the central fossa of the right mandibular first molar. The stress of each part of the models was analyzed by Ansys 15. 0 software. Results Under the same loading condition. the maximum stress value of the implantswas in the neck of the implants. The maximum stress distribution of 8 models showed that the maximum stress value was 40. 12-49. 06 MPa for the 4-implant group and was 80. 62-109. 64 MPa for the 6-implant group, with the latter being two folds that of the former. In two groups, the maximum stress was the lowest when the vertical height reduction was 5 mm. With the decrease of the mandible vertical height. the stress increased gradually. However, the maximum stress of the 0 mm-height-reduced models was larger than that of 5 mm- height-reducedmodels. Conclusion There is no destructive stress under certain extreme load in both 4-implant group and 6-implant group, with the 4-implant group having a more reasonable stress distribution. The 5 mm-hight-reduced models have the minimum stress, indicating that appropriate vertical height reduction can lead to more reasonable implant stress distribution.
ABSTRACT
<p><b>OBJECTIVE</b>To study the relationship between muscle motor evoked potentials (MEP) and hindlimbs motor function in rabbits with spinal cord injury.</p><p><b>METHODS</b>Forty-five rabbits were randomly divided into 9 groups, including one control group and 8 injured groups (receiving Allen's injury of 0, 50, 75, 100, 125, 150, 175, 200, or 250 gcf). Hindlimb strength and muscle MEP were recorded at the 1st day and 4th week postoperatively. At 4 weeks after spinal section, the spinal cord tissue was sampled for histological examination with HE staining and immunohistochemistry with anti-NF antibody of the corticospinal tract fibers.</p><p><b>RESULTS</b>During the operation, MEP showed an all-or-none pattern with significant correlations to postoperative optical density of NF and postoperative hindlimb motor function. The latency prolongation of the muscle MEP at the 4th week showed a linear correlation to the hindlimb Tarlov's score, whereas the MEP amplitude was not correlated to postoperative hindlimb motor function.</p><p><b>CONCLUSIONS</b>The all-or-none pattern of muscle MEP can be used to evaluate the severity of spinal cord injury.</p>
Subject(s)
Animals , Rabbits , Evoked Potentials, Motor , Hindlimb , Pyramidal Tracts , Spinal Cord InjuriesABSTRACT
<p><b>OBJECTIVE</b>To probe into the mechanism of substance-partitioned moxibustion in treatment of primary dysmenorrhea (PD) of cold-damp stagnation type.</p><p><b>METHODS</b>The treatment group (105 cases of PD) were treated with substance-partitioned moxibustion and the control group (104 cases) were treated with Chinese drug Yueyue-shu. Their therapeutic effects were observed. Plasma beta-endorphin contents in menstrual period were determined before and after treatment in 40 patients of each group.</p><p><b>RESULTS</b>The total effective rate of 95.2% in the substance partitioned moxibustion group was better than 85.6% in the control group (P < 0.05); after treatment, plasma beta-endorphin content significantly increased in the substance-partitioned moxibustion group (P < 0.01).</p><p><b>CONCLUSION</b>Substance-partitioned moxibustion has obvious therapeutic effect on primary dysmenorrhea of cold-damp stagnation type, which is carried out possibly through regulating the plasma beta-endorphin content as one of the mechanisms.</p>