垂直矫治曲的力学行为及其影响因素

目的 研究垂直曲的力学行为及其各种形状因素对力学行为的影响特点。方法 应用三维有限元应力分析法,对垂直曲的力学行为及其各种影响因素进行模拟分析。结果 普通垂直曲使牙齿产生移动,其M/F比值过低,无法取得理想的效果。将垂直曲的两臂预成一定的角度可提高M/F比值。垂直曲的安装位置对M/F值影响较大。结论 垂直曲预成一定角度后,M/F将保持恒定的值。改变垂直曲的安装位置,可以实现牙齿的压低、伸长移动。     

垂直曲对弓丝转矩性能的影响研究

目的 :定量分析不同垂直臂高度的垂直曲弓丝的抗扭刚度 ,揭示垂直曲对弓丝第三序列弯曲方向上力学性能的影响的规律 ,为临床合理精确使用转矩力提供依据。材料与方法 :选取 0 .0 2 2英寸标准方丝弓中切牙托槽、横截面尺寸 0 .0 18× 0 .0 2 5英寸不锈钢丝。随机抽取 10根方丝 ,每根方丝制作垂直臂高度分别为 3.5mm、7mm、10 .5mm、14mm的 4种垂直曲弓丝。在 5 .5mm的托槽间距下对垂直曲弓丝的 4 0个样本分别进行转矩实验。结果 :垂直臂为 3.5mm、7mm、10 .5mm、14mm的垂直曲弓丝的抗扭刚度分别为平直弓丝抗扭刚度的 92 .6 %、84 .3%、78.4 %、70 .4 %。垂直臂高度越高 ,降低抗扭刚度的效果越明显。垂直曲的垂直臂每升高lmm ,其抗扭刚度下降 0 .0 84Nmm/度。弓丝弯制造成的塑性形变使弓丝的抗扭刚度下降 2 .998Nmm/度。结论 :垂直曲的加入使弓丝的抗扭刚度降低。曲弯制造成的塑性形变段和曲弯制后保留的直线段均参与了垂直曲设计降低弓丝抗扭刚度的作用。     

垂直矫治曲结构与力学性能的有限元分析

目的:研究垂直曲的结构与力学性能之间的关系,为临床上更好地应用垂直曲提供参考依据。方法:根据垂直曲在应用过程中的作用方式,建立垂直曲的几何模型,应用有限元分析软件ANSYS对曲的力学性能进行模拟计算,最后对其规律进行总结。结果:增加垂直曲的臂长、高度或弯曲半径,曲变形时产生的力和力矩值下降。增加臂长时力和力矩的比值减小,而增加高度和弯曲半径时却增大。加大垂直臂间隙时,产生的力和力矩值增大,而力和力矩的比值变化不大。结论:实际应用中,可适当改变垂直曲的结构,调整曲的力、力矩及力和力矩的比值,以满足治疗中不同个体的需要。     

多曲方丝弓与预成镍钛丝摇椅弓矫治前牙深覆(牙合)的临床效果比较

目的:评价多曲方丝弓和预成镍钛丝摇椅弓治疗前牙深覆(牙合)的临床效果.方法:选择Ⅱ～Ⅲ度深覆(牙合)患者20例,年龄12～27岁,多曲方丝弓组10例,预成镍钛丝摇椅弓组10例,咬合打开前后拍摄头颅侧位片,并进行X线测量.采用SPSS13.0软件包对测量结果进行配对t检验.结果:2种方法咬合打开前后均有切牙压低、磨牙升高,颌骨无明显变化,但多曲方丝弓组打开咬合时间明显短于预成镍钛丝摇椅弓组.结论:2种方法打开咬合的机制基本相同,但多曲方丝弓更有效,是一种快速有效的打开咬合的矫治方法.     

垂直曲的力学行为的研究

目的 研究比较不同材质矫治垂直曲及不同形状的矫治曲的力学特性。方法 利用大型有限元软件 ANSYS进行模拟计算。结果 钛镍丝材料的矫治曲的作用力较符合临床正畸应用;双垂直曲的作用力比垂直曲的柔和的多。结论 掌握各种垂直曲的力学行为的变化规律,可更好地指导临床。     

多曲唇挡的设计、作用及临床应用

目的：探讨多曲唇挡的设计原理、制作、适应证和功能。方法：①介绍多曲唇挡的设计原理和制作。②通过对两例使用多曲唇挡典型病例的介绍,总结多曲唇挡的适应证和功能。结果：多曲唇挡可以起到缺隙保持器、Ｆｒａｅｎｋｅｌ矫治器和增强支抗或推磨牙向后等作用。结论：多曲振挡适应范围广,可以２４ｈ戴用,制作简便,并可预成,患者戴用舒适、隐蔽。     

钛镍预成丝弓矫治替牙期前牙反合

钛镍预成丝弓矫治替牙期前牙反江西省景德镇市牙病防治所口腔正畸专科门诊金世英方法：将钛镍预成丝弓（北医中北医疗技术公司有售），两端在酒精灯下退火，弯成欧米茄曲作阻止点，使丝弓阻止点两端间的弧形长度大于相应现有牙弓弧形长度３～ｓｍｍ。如图：附图示预成钛镍...     

带螺圈簧的弓丝在打开咬合时的应用

固定矫治技术治疗牙颌畸形，常常需要打开咬合，咬合打开快慢决定了矫治时间。临床上发现，用国产弓丝弯制后倾曲打开咬合，时间长，有时发生支抗磨牙倾斜和松动。为提高国产弓丝疗效，防止支抗磨牙倾斜，我们在Ｂｅｇｇ矫治技术中，设计带螺圈簧的弓丝打开咬合，治疗牙颌...     

改良垂直曲治疗唇侧近中阻生尖牙的效果评价

目的:评价改良垂直曲矫治唇侧近中阻生尖牙的效果.方法:选取2011-2014年就诊于西宁市第一人民医院口腔正畸科的单侧唇侧近中尖牙阻生患者5例,采用改良垂直曲进行正畸矫治.结果:5颗唇侧近中阻生尖牙平均牵引时间13.6个月,均成功纳入牙弓并建(牙合).结论:采用改良垂直曲治疗唇侧近中阻生尖牙,可取得良好的效果.     

镍钛丝与附开大垂直曲的澳丝在前牙反牙合矫治中的应用比较

目的　了解附开大垂直的澳丝与镍钛丝在解除牙源性前牙反牙合的区别。方法　对 40例牙源性前牙反牙合患者上颌分别使用附开大垂直曲的澳丝与镍钛丝来解除反牙合 ,并对比了成功病例的牙牙合情况及临床情况。结果　使用附开大垂直曲的澳丝的成功率为 1 0 0 % ,使用镍钛丝的成功率 30 %。结论　附开大垂直曲的澳丝是解除牙源性前牙反牙合的最有效方法之一。     

In vitro hydrolytic degradation of composite quartz fiber-post bonds created by hydrophilic silane couplings

The hydrolytic stability of a pre-activated MPS silane (Monobond-S) and a 2-component 4-META/ gamma-MPTS silane (Porcelain Liner M) to H202-etched quartz fiber posts was investigated using a modeling approach. Composite build-ups around silanized posts were stored dry for 24 hours, stored in deionized water at 37 degrees C for 24 hours, 1 week, 1 month or they were thermocycled. Sectioned specimens were prepared for microtensile bond testing and SEM examination; 4-META/gamma-MPTS silane produced a rapid decline in bond strength after 1 week and 1 month of water storage and after thermocycling. This was not apparent in pre-activated MPS silane. SEM revealed debonding along the post-composite interfaces, which were coupled with 2-component silane. The use of a hydrophilic resin monomer (4-META) for on-demand hydrolysis of the gamma-MPTS silane expedited interfacial water sorption and hydrolytic degradation, which may be prevented with alternative coupling strategies.     

New horizons in orthodontics & dentofacial orthopedics: fixed Twin Blocks & TransForce lingual appliances

During the 20th century functional appliances evolved from night time wear to more flexible appliances for increased day time wear to full time wear with Twin Block appliances. The current trend is towards fixed functional appliances and this paper introduces the Fixed Twin Block, bonded to the teeth to eliminate problems of compliance in functional therapy. TransForce lingual appliances are pre-activated and may be used in first phase treatment for sagittal and transverse arch development. Alternatively they may be integrated with fixed appliances at any stage of treatment.     

Effect of the cross-linking silane concentration in a novel silane system on bonding resin-composite cement

Objective. Four experimental blends of an organo-functional silane monomer with a non-functional cross-linking silane monomer (a novel silane system) were evaluated as adhesion promoters in an experiment in which a resin-composite cement was bonded to silica-coated titanium. Material and Methods. 3-Acryloyloxypropyltrimethoxysilane (as constant 1.0 vol%) was blended with 1,2-bis-(triethoxysilyl)ethane, where its concentration was 0.1, 0.2, 0.3, or 0.5 vol%. Titanium slides (n=20) were grit-blasted, silica-coated, and silanized with four experimental silane solutions, with a pre-activated silane Cimara? (VOCO, Germany) as control. After silanization, resin-composite cement stubs (Bifix? QM; VOCO, Germany) were photo-polymerized. The shear bond strength was measured after dry storage (24 h) or after thermo-cycling (6000 cycles between 5°C and 55°C). The resin stub failure mode was determined. Results. Statistical analysis (ANOVA) showed that type of storage (p <0.05) and concentration of cross-linker silane (p<0.005) both significantly affected the shear bond strength. The highest shear bond strength was obtained with a blend of 1.0 vol% 3-acryloyloxypropyltrimethoxysilane+0.3 vol% 1,2-bis-(triethoxysilyl)ethane, 15.9 MPa (standard deviation SD 3.4 MPa) for both the thermo-cycled group and after dry storage (24 h), 14.3 MPa (SD 4.1 MPa) (n=8/group). The lowest values were obtained with Cimara? silane 7.3 MPa (SD 2.2 MPa) in dry storage and 7.9 MPa (SD 2.0 MPa) obtained with 1.0 vol% 3-acryloyloxypropyltrimethoxysilane+0.1 vol% 1,2-bis-(triethoxysilyl)ethane. The failure type was mainly cohesive. Conclusion. A novel silane system with an optimal concentration of the cross-linking silane may produce significantly higher shear bond strength between silica-coated titanium and resin-composite cement compared to a pre-activated silane product.     

Arch development with trans-force lingual appliances

Trans-Force lingual appliances are designed to correct arch form in patients with contracted dental arches. Interceptive treatment with this new series of pre-activated lingual appliances offers new possibilities for arch development, in combination with fixed appliances. Palatal and lingual appliances insert in horizontal lingual sheaths in molar bands. No activation is required after the appliance is fitted, and this principle is extended to a series of appliances for sagittal and transverse arch development. Both sagittal and transverse appliances have additional components to achieve 3-way expansion where this is indicated. The invisible lingual appliances may be used in correction of all classes of malocclusion at any stage of development, from mixed dentition through permanent dentition, and this approach has wide indications in adult treatment.     

Activation of human natural killer cells by lipopolysaccharide from Actinobacillus actinomycetemcomitans

Lipopolysaccharide (LPS) from the Y4 strain of this bacterium, which is implicated in the pathogenesis of juvenile periodontitis, was incubated with human peripheral blood lymphocytes (PBL) and its action compared to that of LPS from Escherichia coli. Both LPS augmented cytotoxicity measured against natural killer (NK) cell-resistant tumour targets within 24 h of incubation. Cytotoxicity was exclusively found in NK-enriched low-density large granular lymphocyte fractions, as separated by Percoll gradient. LPS activated NK cells without stimulating high levels of proliferation. The minimum concentration of A. actinomycetemcomitans LPS required to activate NK cells was 1 microgram/ml; higher concentrations did not significantly increase this activation. LPS had no synergistic effect on the induction of PBL cytotoxicity by interleukin-2. In contrast, LPS pre-activated monocytes inhibited the induction of lymphocyte cytotoxicity by either interleukin-2 or LPS.     

Antigen-presenting-cell function of interferon γ-treated human gingival fibroblasts

The present study was carried out to examine the antigen-presenting cell (APC) functions of human gingival fibroblasts (HGF) elicited with IFNy. Stimulation of HGF with IFNy clearly induced HLA-DR expression and enhanced expression of intercellular adhesion molecule-1 (ICAM-1) on HGF. Despite the phenotypical resemblance of IFNγ-treated HGF to so-called APC, HLA-DR positive HGF were unable to induce proliferation of allo-reactive peripheral blood T cells (PBT) isolated from different donors. The failure of IFNγ-treated HGF to stimulate unprimed allo-reactive PBT was not due to the lack of production of IL-1 or the immunosuppressive effect of PGE₂ from HGF. On the other hand, the fact that detectable expression of CD80, ligand for CD28, was not found on IFNy-treated HGF may at least in part explain the ineffective function of HGF as APC. Interestingly, IFNγ-treated HGF induced proliferation of primed allo-reactive CD4⁺ T cells in a HLA-DR dependent manner, suggesting that IFNγ-treated HGF may have the ability to stimulate pre-activated T cells. We then confirmed that high levels of IFNγ mRNA were detectable in inflamed gingival tissue. Although it cannot be concluded from this study that HGF are incapable of effectively presenting antigenic peptides to autologous T cells bearing appropriate T cell receptors, present results suggest that HGF may be affected by locally-secreted IFNy and that the IFNγ-stimulated HGF may play a role in regulating immune responsiveness in inflammatory periodontal lesions.     

The effect of five silane coupling agents on the bond strength of a luting cement to a silica-coated titanium.

OBJECTIVES: The adhesive performance of five silane coupling agents in adhering resin composite cement (3M ESPE) to silica-coated titanium was evaluated. Titanium was tribochemically silica-coated by using the Rocatec system. METHODS: Two volume percent solutions of 3-acryloyloxypropyltrimethoxysilane (Toray Dow Corning Silicone), N-[3-(trimethoxysilyl)propylethylenediamine] (Dow Corning), 3-mercaptopropyltrimethoxysilane (Toray Dow Corning Silicone) and bis-[3-(triethoxysilyl)propyl]polysulfide (Dow Corning) were prepared in 95 vol.% acidified ethanol and allowed to activate (hydrolyze). A pre-activated ca. 2 vol.% 3-methacryloyloxypropyltrimethoxysilane (ESPE Sil) was used as a control. The silanes were applied onto silica-coated titanium slides. Chemical activation reactions of the silanes were monitored by Fourier transform infrared spectrometry (Perkin-Elmer Spectrum One). RelyX ARC (3M ESPE) resin composite cement stubs were applied and photo-polymerized onto silica-coated titanium. The specimens were thermo-cycled (6000 cycles, 5-55 degrees C). RESULTS: Statistical analysis (ANOVA) showed that the highest shear bond strength (n=8 per group) value after thermocycling, 14.8 MPa (S.D. 3.8 MPa), was obtained with 2.0 vol.% 3-acryloyloxypropyltrimethoxysilane. Silanization and results with 3-methacryloyloxypropyltrimethoxysilane (control, ESPE Sil) did not statistically differ from 3-acryloyloxypropyltrimethoxysilane, 14.2 MPa (S.D. 5.8). The lowest shear bond strength was 7.5 (S.D. 1.9) MPa for N-[3-(trimethoxysilyl)propylethylenediamine] and 7.5 (S.D. 2.5) MPa for bis-[3-(triethoxysilyl)propyl]polysulfide. Both the type of silane (p<0.001) and storage conditions affected significantly the shear bond strength values (p<0.001). All silanes became activated according to the infrared spectroscopic analysis. SIGNIFICANCE: Silanization with 3-acryloyloxypropyltrimethoxysilane or 3-mercaptopropyltrimethoxysilane might offer an alternative for bonding a luting cement to silica-coated titanium.     

A re-evaluation of the distribution of the elastic meshwork within the periodontal ligament of the mouse

The elastic properties of the periodontal ligament have been attributed, in part, to oxytalan fibers, as no other types of elastic fibers are described there. It has been difficult to study the periodontal elastic meshwork by standard microscopic techniques because it is partially obscured by the adjacent periodontal ligament collagen fibers. Our study employed methods which either completely or partially removed mandibular molar periodontal ligament collagen fibers, exposing a previously undescribed periodontal elastic meshwork. The periodontal elastic meshwork was composed of many elastin lamellae containing both peripheral microfibrils of regular arrangement and central microfibrils of irregular arrangement, which could only be demonstrated in oxidized tissues. Peripheral, regularly arranged bundles of microfibrils resembled oxytalan fibers, which were often adherent to the border of the elastin lamella. Elastin lamellae containing irregular microfibrils resembled elaunin fibers. These fibers probably enclosed either blood vessels, nerves or collagen fiber bundles. Peripheral microfibrils attached elaunin to cementum, alveolar bone, blood vessels, and principal periodontal collagen fibers. Thus, the periodontal elastic meshwork is composed of both oxytalan and elaunin fibers. Microfibrils attach elaunin fibers to the adjacent non-elastic tissue and also form bundles which traverse the periodontal ligament space and are probably the oxytalan fibers demonstrable by light microscopic techniques. This meshwork of oxytalan and elaunin fibers probably contributes to tooth support and maintenance of periodontal homeostasis by dissipating chewing forces and maintaining patency of periodontal blood vessels.     

秦始皇帝陵区出土人第三磨牙的萌出情况

目的：调查秦始皇帝陵区山任陶窑遗址中人体颌骨第三磨牙的萌出情况。方法：选用秦代人体颌骨98副，观察萌出特点，计算阻生率，分析阻生情况。结果：通过对98副标本的观察，发现秦代人同现代人类一样可发生第三磨牙的多种萌出状况，其中包括先天缺失、畸形牙、阻生、正常萌出等。结论：秦始皇帝陵区山任陶窑遗址中人体颌骨具有同现代人类一样的第三磨牙萌出特点。     

The variability of the curvature of the labial surface of the upper anterior teeth along the facial axis of the clinical crown

OBJECTIVE: To mathematically assess the curvature of upper anterior teeth along the facial axis of the clinical crown (FACC) line to provide information valuable for assessment of enamel growth. METHODS: Forty upper study models were chosen from the Orthodontic clinic at the Charles Clifford Dental Hospital, Sheffield, UK. The study model incisors and canines were sectioned longitudinally down the FACC line, using a Microslice II cutting machine. Images were captured that showed the proximal view of the tooth curvature from incisal edge/cusp tip to the gingival margin. The images were converted into silhouettes and saved as bitmap files. These were vectorised and converted to an outline of xy data points. The forty xy files were mathematically adjusted so the distance between incisal edge and gingival margin were of equal length. Non Rotational Principal Component Analysis (PCA) was then applied at 20 equal intervals along the curve of each xy file to describe the shape of the teeth. RESULTS: Intra class correlation coefficient for intra-operator repeatability ranged from 0.821-0.998 showing good or excellent levels of reliability. PCA showed variation between tooth types. CONCLUSIONS: The method proved reliable. All tooth types showed that the mid-point region had the greatest rise variable, indicating that the most-prominent point was central or incisal for central and lateral incisors. All were skewed towards the incisal end and had kurtosis at both ends. Central incisors showed least variability. Greater variability was seen within the incisal third than within the gingival third for all tooth types.