Biomechanical analysis of micro-implant anchorage in the infrazygomatic crest for the distal displacement of the upper dentition at different heights / 中国组织工程研究

BACKGROUND: In orthodontics, micro-implant anchorage in the infrazygomatic crest that cannot damage the tooth root can achieve an unobstructed overall movement of the upper dentition. However, little is reported on the stress and strain of the tooth and alveolar bone during the distal movement of the upper dentition. OBJECTIVE: To set up a three-dimensional finite element model to perform a biomechanical analysis of micro-implant anchorage in the infrazygomatic crest for the distal displacement of the upper dentition at different heights. METHODS: Cone-beam CT data from a female patient admitted for orthodontic treatment was saved in Dicom format, and imported into Mimics 16.01 software. Then, a three-dimensional model of the right maxilla and tooth dentition was made by automatically and manually selecting boundaries. The model was imported into Geomagic8.0 for removal of noise dots and smooth processing, and then it was imported into the Mimics16.01 software and meshed for the surface/body through 3 Matics software. Afterwards, three-dimensional models maxillary denture, archwires and traction hooks and implants were established by ProE5.0, and all the models were imported into ANSYS13.0 and assembled and analyzed for stress and strain analysis. RESULTS AND CONCLUSION: We successfully established the three-dimensional finite element model for biomechanical analysis of micro-implant anchorage in the infrazygomatic crest for the distal displacement of the upper dentition at different heights, and this model conformed to the anatomic features. With the increase of the height of traction hooks (1, 4, 7, 10 mm), the vertical stress of the maxillary teeth increased gradually, and had no correlation with the change of the horizontal stress. With the increase of the height of traction hooks, at the sagittal axis, the strain at midpoints of middle incisors, canine teeth, and first molars decreased gradually and the strain at the root of middle incisors and canine teeth also decreased gradually, but there was no change in the strain at the root of first molars. With the increase of the height of traction hooks, at the vertical axis, the strain at the midpoints and tooth root of middle incisors increased, while the strain of canine crown increased gradually and that of the canine root decreased; the strain at the midpoint of first molars changed a little, and the strain of the tooth root decreased gradually. The dentition rotated from clockwise to counterclockwise. To conclude, the three-dimensional finite element model made in the study is consistent with the anatomic structure, which provides a basis for biomechanical analysis of micro-implant anchorage in the infrazygomatic crest for the distal displacement of the upper dentition. The upper dentition impedance center located in the position of 4 to 7 mm of the arch wire can be used as the microimplant support site in the infrazygomatic crest.

Effect of orthodontic force on inflammatory periodontal tissue remodeling and expression of IL-6 and IL-8 in rats

OBJECTIVE@#To investigate effect of orthodontic force on inflammatory periodontal tissue remodeling and expression of IL-6 and IL-8 in rats.@*METHODS@#Eighty SD rats were randomly divided into 4 groups, blank control group (group A) with 5 rats, treatment normal group (group B) with 25 rats, inflammation control group (group (group C) with 25 rats, inflammation treatment group (group D) with 25 rats. Immunohistochemistry and histomorphometric analysis was performed to measure the expression of IL-6, IL-8 and the first molar to the recent movement in the distance.@*RESULTS@#The expression of IL-8 reached a maximum on day 5 and declined thereafter in group B; the expression of IL-6 reached a maximum on day 5 in group B. The expression of IL-6 and IL-8 was gradually weakened with time in group C. The expression of IL-6 and IL-8 were high, and reached a maximum on day 5 and declined thereafter in group D. AD of positive cells in group D were higher than group B at each time point (P<0.05). The time which 0.49 N orthodontic force was loaded was longer, orthodontic tooth movement distance was greater. Movement distance in group D were longer than group B (P<0.05).@*CONCLUSIONS@#Orthodontic force as well as inflammatory stimulus can evoke the expression of IL-6 and IL-8. Under the combined effects of inflammation and orthodontic force, the expression of IL-6, IL-8 will increase.

The polymorphism distributions of MICA and MICB microsatellite in Guangdong Han population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the genetic polymorphism of microsatellite in the exon 5 of MICA gene and the intron 1 of MICB gene in Guangdong Han population.</p><p><b>METHODS</b>One hundred and six samples of Guangdong Han population were genotyped by polymerase chain reaction and fluorescent technique (6-FAM). Gene frequency, power of discrimination, expected heterozygosity, polymorphism information content and probability of paternity exclusion were calculated.</p><p><b>RESULTS</b>The genotype distributions of MICA and MICB microsatellite met Hardy-Weinberg equilibrium. MICA A5 was the most common allele (0.2877), whereas A4 was the least popular one (0.1321). The genotype distribution frequencies of A5-5.1 (14.15%) and A5-5 (10.38%) are high. MICB CA14 was the most common allele (0.3255), and CA19,28 was the least popular one (0.0047). CA27 was not observed. The genotype distribution frequency of CA14-CA14(14.15%) is high.</p><p><b>CONCLUSION</b>The microsatellite of the exon 5 of MICA gene and the intron 1 of MICB gene could be used as the genetic markers of Chinese population in the studies of anthropology, linkage analysis of genetic disease genes, individual identification and paternity test in forensic medicine.</p>

The genetic characteristic of HLA-DRB1 locus in the Jiangsu-Zhejiang-Shanghai Han population and a comparison of its frequency distribution with that of other populations / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the genetic polymorphism of HLA-DRB1 locus in Jiangsu-Zhejiang-Shanghai Han population and analyze the characteristic of the allele frequency distribution in comparison with that of other populations.</p><p><b>METHODS</b>The technique of polymerase chain reaction-sequence specific primers (PCR-SSP) and reverse polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) was adopted in genotyping a sample of 626 unrelated healthy individuals collected from a Chinese Han population in Jiangsu-Zhejiang-Shanghai area. HLA-DRB1*0101-1001, DRB3, DRB4 and DRB5 were detected. The allele frequency of HLA-DRB1 was calculated, and the allele frequency distribution of HLA-DRB1 in this population was compared with the results from other populations.</p><p><b>RESULTS</b>HLA-DRB1*0101, 0301, 0701, 09012, 1001, 1201, 1202, 1301/02, 1303/04, 1401/04/05, 1402/03/1305, 1501/02, 16021 and 04xx, 08xx were detected in Jiangsu-Zhejiang-Shanghai Han population. The common HLA-DRB1*allele included 09012(17.97%), 04xx(12.53%), 1202(11.42%) and 1501/02(11.02%). The polymorphism information content is 0.9024, and expected heterozygosity is 0.9634 in Jiangsu-Zhejiang-Shanghai Han population.</p><p><b>CONCLUSION</b>The HLA-DRB1 distribution of Jiangsu-Zhejiang-Shanghai Han population shares some genetic characteristic with other Han populations, but it exhibits its own characteristic, suggesting the intermediate state of this population between the southern and northern Han populations. The polymorphism of HLA-DRB1 of Jiangsu-Zhejiang-Shanghai Han population is the most abundant one in this study.</p>