肯氏Ⅰ、Ⅱ类牙列缺损数字化印模及模型在可摘局部义齿中的应用

目的评估肯氏Ⅰ、Ⅱ类牙列缺损数字化印模及树脂模型技术在可摘局部义齿(RPD)中的应用效果。方法选择肯氏Ⅰ、Ⅱ类牙列缺损患者,按照义齿制作流程分组:数字化印模/树脂模型/钴铬合金铸造支架组(A组)、数字化印模/树脂模型/激光打印钛支架组(B组)、藻酸盐印模/石膏模型/钴铬合金铸造支架组(C组)、藻酸盐印模/石膏模型/激光打印钛支架组(D组),每组40例。对最终完成的RPD在口内就位情况进行检查,评估指标包括卡环固位力、连接体和基托在口内的密合度、咬合准确度,各项指标评估分值使用Kruskal-Wallis秩和检验进行分析。结果4组RPD各项指标的评分值差异无统计学意义。结论利用数字化印模及树脂模型完成的铸造钴铬合金和激光打印钛支架式RPD能够满足肯氏Ⅰ、Ⅱ类牙列缺损患者的临床修复要求。

Orthodontic-surgical treatment for severe skeletal class Ⅱ malocclusion with vertical maxillary excess and four premolars extraction: A case report

BACKGROUND Patient satisfaction with facial appearance at the end of orthodontic camouflage treatment is very important, especially for skeletal malocclusion. This case report highlights the importance of the treatment plan for a patient initially treated with four-premolar-extraction camouflage, despite indications for orthognathic surgery.CASE SUMMARY A 23-year-old male sought treatment complaining about his unsatisfactory facial appearance. His maxillary first premolars and mandibular second premolars had been extracted, and a fixed appliance had been used to retract his anterior teeth for two years without improvement. He had a convex profile, a gummy smile, lip incompetence, inadequate maxillary incisor inclination, and almost a class I molar relationship. Cephalometric analysis showed severe skeletal class Ⅱ malocclusion(A point-nasion-B point = 11.5°) with a retrognathic mandible(sella-nasion-B point = 75.9°), a protruded maxilla(sella-nasion-A point = 87.4°), and vertical maxillary excess(upper incisor to palatal plane = 33.2 mm). The excessive lingual inclination of the maxillary incisors(upper incisor to nasion-A point line =-5.5°)was due to previous treatment attempts to compensate for the skeletal class Ⅱ malocclusion. The patient was successfully retreated with decompensating orthodontic treatment combined with orthognathic surgery. The maxillary incisors were repositioned and proclined in the alveolar bone, the overjet was increased, and a space was created for orthognathic surgery, including maxillary impaction, anterior maxillary back-setting, and bilateral sagittal split ramus osteotomy to correct his skeletal anteroposterior discrepancy. Gingival display was reduced, and lip competence was restored. In addition, the results remained stable after 2 years. The patient was satisfied with his new profile as well as with the functional malocclusion at the end of treatment.CONCLUSION This case report provides orthodontists a good example of how to treat an adult with severe skeletal class Ⅱ malocclusion with vertical maxillary excess after an unsatisfactory orthodontic camouflage treatment. Orthodontic and orthognathic treatment can significantly correct a patient’s facial appearance.

青少年骨性Ⅱ类错合畸形患者功能矫治前后3D面相变化的研究

目的 利用3D诊断技术对青少年骨性Ⅱ类患者面部软组织进行三维重建,分析治疗前后患者面部软组织变化。方法收集20例青少年骨性Ⅱ类下颌后缩的患者,采用功能矫治器导下颌向前促进下颌骨发育,纠正上下颌骨发育不调,每位患者治疗前后均采用3D相机获取患者面相资料,对比分析治疗前后患者软组织三维方向变化情况。结果 SNA,SNB,L1-MP增大,ANB,U1-SN减小,上唇厚度,下唇厚度,Pog-零子午线距离减小,口裂-颏下距,鼻唇角,唇齿角增大,差异均有统计学意义(P<0.05)。结论 青少年骨性Ⅱ类错合畸形患者功能矫治前后3D面相唇部厚度减小,凸度改善,颏部前伸,软组织侧貌更加协调美观。

高角Ⅱ类开[牙合]患者上下颌前牙根长及中切牙冠根形态的锥形束CT研究

目的探讨高角Ⅱ类前牙开[牙合]患者的上下颌前牙牙根长度及中切牙冠根形态,为临床正畸治疗提供参考。方法本研究已通过单位伦理委员会审查批准,并获得患者知情同意。对81例高角Ⅱ类患者(前牙开[牙合]40例、正常覆[牙合]41例)正畸治疗前的锥形束CT(cone-beam computed tomography,CBCT)图像进行分析,运用Dolphin软件对上下颌前牙的牙根长度以及中切牙冠根形态进行研究,并行统计学分析。结果高角Ⅱ类开患者(开[牙合]组)与高角Ⅱ类正常覆患者(正常覆[牙合]组)的上颌尖牙和侧切牙牙根长度差异无统计学意义,但开[牙合]组上颌中切牙(11.12±1.37)mm、下颌中切牙(10.15±1.09)mm、下颌侧切牙(11.27±1.15)mm和下颌尖牙(12.81±1.48)mm的牙根长度均较正常覆[牙合]组短且差异均具有统计学意义(P<0.05);另一方面,开[牙合]组的上颌中切牙冠根成角(1.10°±3.62°)显著小于正常覆[牙合]组(4.53°±2.30°)(P<0.01),而开[牙合]组的下颌中切牙冠根成角与正常覆[牙合]组的差异无统计学意义。结论高角Ⅱ类开[牙合]患者的上下颌中切牙、下颌侧切牙和下颌尖牙牙根均较高角Ⅱ类正常覆[牙合]患者短,高角Ⅱ类开[牙合]患者上颌中切牙牙冠长轴相对于牙根长轴偏唇侧,冠根成角较小,利于开[牙合]患者的前牙转矩控制或内收移动。

无托槽隐形矫治联合牙周组织再生术治疗重度牙周炎伴Ⅱ类错颌畸形患者的临床疗效

目的:探讨无托槽隐形矫治联合牙周组织再生术(Guided tissue regeneration,GTR)在重度牙周炎伴Ⅱ类错颌畸形矫治患者中的应用价值。方法:选取浚县人民医院2018-09至2022-012022-12收治的130例重度牙周炎伴Ⅱ类错颌畸形患者,随机分为无托槽隐形矫治组和常规矫治组,各65例。常规矫治组在GTR术基础上进行金属直丝弓托槽矫治,无托槽隐形矫治组在GTR术基础上联合无托槽隐形矫治。矫治6m后,比较两组临床疗效、疼痛介质(P物质、前列腺素E_(2)(Prostaglandin E_(2),PGE_(2))、降钙素基因相关肽(Calcitonin gene-related peptide,CGRP))、龈沟液炎性因子(细胞间黏附因子-1(Intercellular cell adhesion molecule-1,ICAM-1)、白细胞介素-1β(Interleukin-1β,IL-1β)、基质金属蛋白酶8(Matrix metalloproteinase-8,MMP8))、牙周改善情况(牙周探诊深度(Periodontal depth,PD)、龈沟出血指数(Sulcus bleeding index,SBI)、牙菌斑指数(Plaque index,PLI)、牙龈指数(Gingivalindex,GI))、牙齿功能(咬合力、咀嚼效率)及不良反应情况。结果:矫治6m后,无托槽隐形矫治组总有效率高于常规矫治组(P<0.05);与矫治前相比,矫治6 m后,两组龈沟液P物质、PGE_(2)、CGRP、ICAM-1、IL-1β、MMP8水平、PD、SBI、PLI、GI均降低,咬合力、咀嚼效率均升高,且无托槽隐形矫治组改善程度更为显著(P<0.05);无托槽隐形矫治组不良反应发生率低于常规矫治组(P>0.05)。结论:无托槽隐形矫治联合GTR术用于重度牙周炎伴Ⅱ类错颌畸形患者可提高矫治效果,减轻龈沟液炎性程度,改善牙周状况,有助于减轻患者疼痛,增强牙齿功能,且具有较好安全性。

新城疫病毒ClassⅠ与ClassⅡ毒株交叉血凝抑制试验快速分类

ClassⅠ新城疫病毒(NDV)分离自健康家禽泄殖腔棉拭子,其基因序列与ClassⅡNDV存在很大差异,为了建立简单快速的NDV分类方法,用SPF鸡制备ClassⅠ和ClassⅡ毒株多价抗血清分别与选取的ClassⅠ和ClassⅡ代表毒株进行交叉血凝抑制反应。结果表明所有ClassⅠ毒株比同ClassⅡ毒株的交叉血凝抑制值高8～64(3～6log2)倍;而ClassⅡ毒株与ClassⅡ抗血清的HI效价比同ClassⅠ毒株的交叉血凝抑制值高2～8(1～3log2)倍,结果与基因分型高度一致,说明可以用交叉血凝抑制试验进行初步分类。本研究结果显示,NDVClassⅠ弱毒株血凝性与广泛应用的NDV弱毒疫苗株不同,基因序列分析可以部分解释这种差异,另外可能HN蛋白的空间结构也会影响其与血凝素结合的特性。

牙鲆MHC class ⅡB基因多态性及其与鱼体抗病力关系的分析

用fmhcN1和fmhcC1引物分别从42尾感病个体和42尾抗病个体的基因组DNA中扩增MHC基因片段,扩增产物长度为268/280 bp。在268/280 bp的核苷酸序列中,有32个(11.4%)核苷酸位点是多态的。在其编码的61个氨基酸位点中,有13个位点是多态的,其中有6个位点发生在多肽结合位点上。对核苷酸替代的类型及位点进行分析,发现非多肽结合位点的非同义碱基替代率与同义碱基替代率的比值(dN/dS)(0.523)远远小于多肽结合位点的非同义碱基替代率与同义碱基替代率的比值(dN/dS)(23.091),表明氨基酸替换集中出现在exon2多肽结合位点上。分析84个个体的411个阳性克隆的测序结果,发现有13个不同的MHC classⅡB等位基因,并且分别编码13个不同的氨基酸序列。其中大部分等位基因如a,b,c,d,e,f,j,k,i,m是两个群体共有的,等位基因d在感病群体中出现的频率(23.80%)显著高于在抗病群体中出现的频率(7.14%)。而等位基因g和h只出现在13个抗病个体中,其频率分别为21.4%和9.52%;等位基因l只出现在感病群体中,其频率为19.05%。

A Study of Monocyte Excretion of TNF- α and IL-6 and Monocyte Expression of HLA Class Ⅱ Antigen In Genital Herpes

Objective: To study the role of monocytes in the pathogenesis of genital herpes. Methods: TNF- α and IL-6 levels in 27 cases of genital herpes were detected by enzyme linked immunosorbant assay (ELISA). HLA class Ⅱ antigen expression on monocytes were detected by an alkaline phosphatase anti-alkaline phosphatase method. Results: Compared with normal controls, levels of TNF- a and IL - 6 secreted by monocytes responding to LPS mitogen in vitro were significantly decreased [(3.13 ± 0.44ng/ml) vs (4.68 ± 0.54ng/ml), P<0.05 and (3.32 ± 1.06ng/ml) vs (6.46 ± 1.94ng/ ml), P<0.05, respectively]. HLA class Ⅱ antigen expression on monocytes in the genital herpes group was also significantly decreased [HLA-DR (67.48% ± 1.51%) vs (81.03% ± 1.32%), P<0.01 and HLA-DQ (29.54% ± 1.15%) vs (37.63% ± 1.79%), P <0.01 respectively]. Conclusion: These findings suggest that the decreased monocyte function may contribute to the pathogenesis of genital herpes. Augmenting or inducing monocyte function may be important in the prevention, treatment, and reduction of genital herpes cases.

ClassⅡ细菌素乳酸菌的筛选与定性及群体感应系统鉴定

筛选具有Class Ⅱ细菌素群体感应系统广谱抑菌作用的乳酸菌并进行鉴定,为产Class Ⅱ细菌素乳酸菌的研究应用奠定基础。将排除过氧化氢和有机酸干扰作用的10株乳酸菌,经胰蛋白酶、胃蛋白酶和蛋白酶K处理,采用牛津杯法筛选具有分泌细菌素广谱抑菌效果的乳酸菌和最小抑菌实验检测其最小抑菌浓度,通过16S rDNA同源性分析构建系统发育树,设计合成乳杆菌Class Ⅱ细菌素5个操纵子plnEFI、plnJKLR、plnGHSTUV、plnABCD和plnMNOP的特异性引物,PCR和电泳鉴定L-4分泌Class Ⅱ细菌素基因群体感应系统,通过UPLC和尿素-SDS-PAGE确定细菌素的分子质量。L-4为可能具有广谱抑菌作用革兰氏阳性植物乳杆菌,它对指示菌产生的抑菌圈分别为(18.83±0.39)mm和(19.96±0.49)mm,最小抑菌浓度分别为55μg/mL和57μg/mL;L-4具有分泌Class Ⅱ细菌素群体感应基因系统,能够分泌分子质量为10 ku蛋白类细菌素且符合Class Ⅱ细菌素分子量大小范围。L-4是1株具广谱抑菌作用且能分泌10 ku Class Ⅱ细菌素的植物乳杆菌。

两种评分方法在 G.V. Black Ⅱ类洞预备中的对比研究

目的:探讨Fair Grader 100三维评价系统和教师评分两种评分方法对G.V.Black Ⅱ类洞的评价有无差异,并评价教改前后学生预备Ⅱ类洞的质量。方法:选取广州医科大学口腔医学专业2017级本科生为研究对象,分别收集试验组和对照组预备的Ⅱ类洞样本,用上述两种评价方法对两组样本评分,并进行统计学分析。结果:试验组成绩优于对照组成绩,有统计学差异(P<0.01);两种评分方法的结果一致,无统计学差异(P>0.05)。结论:Fair Grader 100数字化评估系统可以在实验课教学中推广使用。

草药S抑制大鼠移植肾排斥反应中MHC Class Ⅱ分子表达的研究

为探索草药Ｓ抗大鼠同种异体肾移植急性排斥的作用机理，采用改进的Ｆａｂｒｅ和Ｋａ－ｍａｄａ大鼠原位肾移植模型，将ＳＤ大鼠肾移植给Ｗｉｓｔａｒ大鼠为同种异体移植，Ｗｉｓｔａｒ移植给Ｗｉｓｔａｒ大鼠为同品系移植（空白对照），共设五个实验组，观察移植后受体鼠存活、检测移植肾功能及定量测定移植肾内ＭＨＣＣｌａｓⅡ抗原分子的表达。结果表明，草药Ｓ能延长受体鼠存活时间，并抑制ＭＨＣＣｌａｓⅡ在移植肾内的表达（与不用药物组比较Ｐ＜０．０１），Ｓ药加小剂量环孢素Ａ（ｃｙｃｌｏｓｐｏｒｉｎｅＡ，ＣｓＡ）治疗组与同系组相比差异无显著性（Ｐ＞０．０５）。这些结果提示，移植肾内ＭＨＣＣｌａｓｓⅡ表达水平的高低与其排斥的强弱有相关性。

H pylori receptor MHC classⅡcontributes to the dynamic gastric epithelial apoptotic response

AIM： To investigate the role of MHC class Ⅱ in the modulation of gastric epithelial cell apoptosis induced by H pylori infection. METHODS： After stimulating a human gastric epithelial cell line with bacteria or agonist antibodies specific for MHC class Ⅱ and CD95, the quantitation of apoptotic and anti-apoptotic events, including caspase activation, BCL-2 activation, and FADD recruitment, was performed with a fluorometric assay, a cytometric bead array, and confocal microscopy, respectively. RESULTS： Pretreatment of N87 cells with the anti-MHC class ⅡIgM antibody RFD1 resulted in a reduction in global caspase activation at 24 h of H pylori infection. When caspase 3 activation was specifically measured, crosslinking of MHC class Ⅱ resulted in markedly reduced caspase activation, while simple ligation of MHC class Ⅱ did not. Crosslinking of MHC class Ⅱ also resulted in an increased activation of the anti-apoptosis molecule BCL-2 compared to simple ligation. Confocal microscope analysis demonstrated that the pretreatment of gastric epithelial cells with a crosslinking anti-MHC class Ⅱ IgM blocked the recruitment of FADD to the cell surface. CONCLUSION： The ability of MHC class Ⅱ to modulate gastric epithelial apoptosis is at least partially dependent on its crosslinking. The crosslinking of this molecule has anti-apoptotic effects during the earlier time points of Hpylori infection. This effect is possibly mediated by the ability of MHC class Ⅱ to modulate the activation of the pro-apoptotic receptor Fas by blocking the recruitment of the accessory molecule FADD, and this delay in apoptosis induction could allow for prolonged cytokine secretion by Hpylori-infected gastric epithelial cells.

H pylori receptor MHC class Ⅱ contributes to the dynamic gastric epithelial apoptotic response

AIM： TO investigate the role of MHC class Ⅱ in the modulation of gastric epithelial cell apoptosis induced by H pylori infection. METHODS： After stimulating a human gastric epithelial cell line with bacteria or agonist antibodies specific for MHC class Ⅱ and CD95, the quantitation of apoptotic and anti-apoptotic events, including caspase activation, BCL-2 activation, and FADD recruitment, was performed with a fluorometric assay, a cytometric bead array, and confocal microscopy, respectively. RESULTS： Pretreatment of N87 cells with the anti-MHC class Ⅱ IgM antibody RFD1 resulted in a reduction in global caspase activation at 24 h of H pylori infection. When caspase 3 activation was specifically measured, crosslinking of MHC class Ⅱ resulted in a marked reduced caspase activation, while simple ligation of HHC class Ⅱ did not. Crosslinking of HHC class Ⅱ also resulted in an increased activation of the anti-apoptosis molecule BCL-2 compared to simple ligation. Confocal microscope analysis demonstrated that the pretreatment of gastric epithelial cells with a crosslinking anti-HHC class Ⅱ IgH blocked the recruitment of FADD to the cell surface. CONCLUSION： The results presented here demonstrate that the ability of MHC class Ⅱ to modulate gastric epithelial apoptosis is at least partially dependent on its crosslinking. Furthermore, while previous research has demonstrated that MHC class Ⅱ signaling can be proapoptotic during extended ligation, we have shown that the crosslinking of this molecule has anti-apoptotic ef-fects during the earlier time points of Hpylori infection. This effect is possibly mediated by the ability of MHC class Ⅱ to modulate the activation of the pro-apoptotic receptor Fas by blocking the recruitment of the accessory molecule FADD, and this delay in apoptosis induction could allow for prolonged cytokine secretion by Hpyloriinfected gastric epithelial cells.

Sequence Comparison of MHCClassⅡβ(Exon 2)and Phylogenetic Relation-ship Between Poultry and Mammalian

A fragment spanning over exon 2 and intron 2 of major histocompatibility complex B-LB Ⅱ genes was amplified using PCR, cloned and sequenced in 13 individuals from eight Chinese indigenous chicken breeds and one introduced breed. Another 41 sequences of MHC class Ⅱ β from ten vertebrate species were cited from the NCBI GenBank. Thirteen new B-LB Ⅱ alleles were found in the chicken breeds sampled. Alignment of the exon 2 sequences revealed 91.1-97.8% similarity to each other within the chickens sampled, and the chickens shared 84.1-87.0% homology to Phasianus colchicus, 78.5-81.5% similarity to Coturnix japonica. The sequences in poultry showed 62.6-68.1% identity to HLA-DRB1, 50-61.5% similarity to DQB (HLA-, SLA- and H2-BB), 53.7-60% to HLA-DPB and 53.3-57.8% similarity to HLA-DOB. The frequency of nonsynonymous substitutions of nucleotide was higher than that of synonymous substitutions, and the frequencies of nonsynonymous and synonymous substitutions in poultry B-LB Ⅱ genes were lower than those observed in mammalian DRB1 and DQB1 genes. The deduced amino acid sequences of MHC class Ⅱ β1 domain exhibited extreme difference in conversed region and variable region patterns among the various species, but the two conserved cysteines forming disulfide-bond were shown consistent in poultry with that in mammalian species; and the carbohydrate attachment site was found more conserved in chicken, Homo sapiens, Bos taurus, Ovis aries and Capra hircus than in Sus scrofa and rodent animals. Compared with exon 2 of DQB1 genes of Homo sapiens, ruminant species and Sus scrofa, the differentia that the deletion of six nucleotides at position195 to 200 of exon 2 of DQB1 genes, and insertion of three nucleotides at position 247 to 249 of the exon 2 existed in rodent species were found, which led to the absence of three AA residues at position 65, 66, and 67 within β1 domain of DQB1 chain, and the insertion of one AA residue at position 85. The difference of the deletion of six nucleotides at position 72 to 77 of exon 2 of DPB1 genes was observed with Homo sapiens DQB1, which caused absence of three AA residues at position 24, 25, and 26 of β1 domain of DPB1 chain. The phylogenetic tree revealed that the B-LB Ⅱ sequences from poultry are not orthologous to the class Ⅱ MHC β-chain genes of mammalian species. The tree indicated that genetic evolutionary relationship of chickens with Phasianus colchicus was much closer than with Coturnix japonica, and the DQB and DPB clusters are more tightly related to each other than to the remaining clusters.

Successful Treatment of Postpeak Stage Patients with ClassⅡ Division 1 Malocclusion Using Non-extraction and Multiloop Edgewise Archwire Therapy: A Report on 16 Cases

Aim To determine cephalometrically the mechanism of the treatment effects of non-extraction and multiloop edgewise archwire （MEAW） technique on postpeak Class Ⅱ Division 1 patients. Methodology In this retrospective study, 16 postpeak Class Ⅱ Division 1 patients successfully corrected using a non-extraction and MEAW technique were cephalometrically evaluated and compared with 16 matched control subjects treated using an extraction technique. Using CorelDRAW software, standardized digital cephalograms preand post-active treatments were traced and a reference grid was set up. The superimpositions were based on the cranial base, the mandibular and the maxilla regions,and skeletal and dental changes were measured. Changes following treatment were evaluated using the paired-sample t-test. Student＇s t-test for unpaired samples was used to assess the differences in changes between the MEAW and the extraction control groups. Results The correction of the molar relationships comprised 54% skeletal change （mainly the advancement of the mandible） and 46% dental change. Correction of the anterior teeth relationships comprised 30% skeletal change and 70% dental change. Conclusion The MEAW technique can produce the desired vertical and sagittal movement of the tooth segment and then effectively stimulate mandibular advancement by utilizing the residual growth potential of the condyle.

Immunohistochemical Studies of Macrophages and MHC Class Ⅱ -positive Cells in the Iris and Ciliary Body of Lewis Rats

Purpose:To investigate the density, distribution and morphology of macrophages and MHC class II -positive dendritic cells in the iris and ciliary body of lewis rats. Methods:Immunohistochemistry was performed using monoclonal antibodies specific to monocytes and macrophages (ED1,ED2) and MHC class II -positive cells (OX6) on wholemounts of the iris-ciliary body complex isolated form normal lewis rats.Results:A well developed network of macrophages was present in the iris and ciliary body of normal lewis rats. These cells, morphologically displaying dendriti-form or pleiomorphic appearance, were more densely arranged in mid-iris (950 + 189 cells/mm2) than in iris base (482 ± 78 cells/mm2) and pupil margin (595 ± 92 cells/mm2). A similar network of MHC class II -positive cells with a cell density 452 ± 78 cells/mm2 was almost uniformly distributed in the iris of normal lewis rats.Conclusions : A network of macrophages and MHC class II -positive cells was established in the iris and ciliary body of

Relationship between polymorphism of class Ⅱ transactivator gene promoters and chronic hepatitis B

AIM: To investigate the relationship between the polymorphism of class Ⅱ transactivator (CIITA) gene promoters and chronic hepatitis B (CHB). METHODS: Genomic DNA was prepared from peripheral blood leukocytes. Promoters Ⅰ,Ⅲ and Ⅳ of gene were analyzed respectively with polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) in 65 patients with CHB, 26 patients with acute hepatitis B (AHB) and 85 normal controls. RESULTS: No abnormal migration was found in PCR-SSCP analysis of the three promoters in the three groups. Also, no sequential difference was observed at the three promoters among the CHB patients, AHB patients and normal controls. CONCLUSION: No polymorphism in promoters I, III and IV of CIITA gene exists in CHB patients, ABH patients and normal controls, suggesting that the promoter of CIITA gene might be a conserved domain.

Distalization of maxillary molars for Class Ⅱ malocclusion with Chinese Ni-Ti coil-springs appliance

Objective: To evaluate the effects of the Chinese Ni-Ti coil-springs appliance on distalization of maxillary molars and the reciprocal effects on the anchorage teeth. Methods:Twenty-four adolescent patients(12 boys,12 girls) with Class Ⅱ malocclusion were selected and the coil-springs appliance was used during the treatment. Pre- and postdistalization lateral cephalometric radiographs were analyzed and compared. Results: The average time for the correction of Class Ⅱ molar relationship was 4.6 months. And the mean distance of molar distalization was 4.4 mm. The Chinese Ni-Ti coil-springs also demostrated less tipping and better bodily movement of maxillary molars. Conclusion: This study suggests that the Chinese Ni-Ti coil-springs appliance distalizes the upper molar significantly, while there is no remarkable loss of anchorage because of patients’ wearing headgear with J hooks at night and Class Ⅱ elastics in the day time.

改进NSGA-Ⅱ算法在水库流量控制系统中的应用

针对NSGA-Ⅱ采用的拥挤度距离策略在区分个体时存在无法有效识别有希望个体缺陷的问题,分析了产生拥挤度距离缺陷的原因,提出以目标函数和为标准的评价机制。基于该机制,进一步提出了改进NSGA-Ⅱ算法。采用DTLZ测试集和多个对比算法测试改进NSGA-Ⅱ算法的性能,并将改进NSGA-Ⅱ应用于水库流量控制系统优化问题。研究结果表明:改进NSGA-Ⅱ在综合性能方面超过大多数对比算法,在实际工程优化中也表现出出色的性能,具有实用性。

Soft and Hard Tissue Changes Following Treatment of Class Ⅱ Division 1 Malocclusion with Twin-Block and Myofunctional Appliance: A Pilot Study

Background Many cases of ClassⅡdeformities have been reported to be treated with prefabricated appliances.The aim of this study was to distinguish the clinical effect of traditional custom-made appliances and prefabricated appliances in the treatment of ClassⅡdivision 1 malocclusion.Therefore,soft and hard tissue changes following treatment of ClassⅡdivision 1 malocclusion using the twin-block(TB)appliance was compared to that using the Myofunctional Research Company(MRC)appliance(K1+K2)combined with oral myofunctional treatment(OMT)(MRC+OMT).Methods The study included 22 children(6 boys and 16 girls aged 9–11 years)with ClassⅡdivision 1 malocclusion along with mandibular retrognathism with a 5–12 mm overjet,basic normal maxillary status,and stage 2 or 3 cervical vertebral maturation(CVM).Participants were randomly assigned into two groups,the TB group and the MRC+OMT group for 12 months.Standardized lateral cephalograms were used to assess skeletal,dental,and soft tissue changes from pre-to post-treatment.Independent t-tests were used to compare the initial and final cephalometric status and tissue changes between the groups.Results The TB and MRC+OMT groups resulted in different degrees of lateral changes;however,improvements of skeletal and soft tissue indices were significantly greater in the TB group than in the MRC+OMT group.Conclusion TB was more effective than MRC+OMT in treating children aged 9–11 years with ClassⅡdivision 1 malocclusion.However,further research using custom-made appliances with OMT is recommended,and further investigations are needed to confirm these findings.