Finite Element analysis on space closure of central incisors using invisible appliance with different material hardness / 医用生物力学

Objective To analyze the mechanical effect of invisible appliances with different material hardness and provide theoretical basis for selecting the suitable material for invisible appliance and its clinical application. Methods Three different three-dimensional (3D) finite element models of invisible appliance were established, of which the elastic modulus was chosen as 415.6, 816.308 and 2 400 MPa, respectively. In these models, the upper central incisors were all designed to move 0.3 mm mesially. Then 3D nonlinear finite element method was used to analyze the stress-distribution in invisible appliance, teeth and periodontal ligament and the instant displacement of every tooth. The comparative study was made among three invisible appliances with different hardness． Results Under experimental condition, the most instant stress and displacement of teeth was the upper central incisor, with initial displacement greater in crown section than that in apical section and the greatest displacement was 0.17 mm. The tendency of central incisor movement was tipping in all situations. The movement of lateral incisor had the second greatest distance (the greatest displacement was 0.10 mm) and the tendency of its movement was in the opposite directions of aimed teeth. When elastic modulus of material decreased, the stress on the invisible appliance increased. The stress in periodontal ligament and the displacement of aimed teeth were also increased. Conclusions If the hardness of invisible appliance increases, the displacement of the designed tooth and treatment efficacy increases, but the appliance with more hardness couldn’t provide better ability in controlling of orthodontic tooth movement. The study suggested clinicians should use attachments or cooperate with fixed appliance to help move teeth bodily.

MBT straight wire for Class II division I malocclusion cases / 中南大学学报(医学版)

OBJECTIVE@#To evaluate the therapeutic effects of MBT straight wire on extraction case of Class II division I.@*METHODS@#Thirty-six class II division I malocclusion patients were treated with MBT straight wire by extracting 4 bicuspid premolars or 2 maxillary bicuspid premolars. The X-ray cephalograms were analyzed before and after the treatment of MBT straight wire.@*RESULTS@#After the treatment, the overjet was reduced by 6.04 mm (P < 0.01); U1-NA was reduced by 15.43 degrees (P <0.01); and U1-NA (mm) was reduced by 4.71 mm (P <0.01). ANB was significantly reduced (P < 0.05).@*CONCLUSION@#MBT straight wire not only shortens the operation but also shows superior effect for Class II division I malocclusion cases.

Advances in Herpesviruses-encoded MicroRNAs / 中国生物工程杂志

MicroRNAs (miRNAs) are small (approximately 22 nt) RNAs that exhibit a diversity in sequence,structure,abudance,and expression profile. Bioinformatic approaches and direct cloning methods have identified 3518 miRNAs from various species. MiRNAs play a pivotal role in the regulation of genes involved in diverse processes such as development,differentiation,and cellular growth control. Recently,many viral-encoded miRNAs have been discovered, most from the herpesviruses viral family. Virus-encoded miRNAs seem to evolve rapidly and regulate both the viral life cycle and the interaction between viruses and their hosts. The detailed study on the virus-encoded microRNAs and the role they play in the progress of viral infection,replication and expression will be beneficial to understand viral molecular biology,and also provide new strategies for the prevention and treatment of virus.

Gene chip analysis of mutation of HBV-DNA open reading frame / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To detect the mutation of HBV-DNA open reading frame (ORF), provide evidences for clinical diagnosis and treatment.</p><p><b>METHODS</b>By using gene chip technique, HBV-DNA was amplified by PCR, incorporated with fluorescence, hybridized with oligonucleotide to detect the gene sequence of DNA by computer analysis and observe the natural mutation of HBV-DNA ORF.</p><p><b>RESULTS</b>The mutations of HBV-DNA ORF existed widespread. The rates of mutation on Pre-C 1896, PreC 1814, BCP 1762, BCP 1764, P 528, P 552MI, P 552MV were 23.5%, 3.9%, 55.9%, 53.9%,39.2%, 38.2%, 10.8%, respectively.</p><p><b>CONCLUSION</b>The gene chip technique possesses extremely high sensitivity and reliability,it is one of the effective methods to detect gene mutation. The mutation of HBV-DNA has important influence on the stability and progress of the disease, and on the judgement of prognosis.</p>