Effect of self-ligating bracket appliance on the periodontal tissues in patients with chronic periodontitis after orthodontic treatment

Objective:To explore the effect of self-ligating bracket appliance on the periodontal tissues in patients with chronic periodontitis after orthodontic treatment.Methods:A total of 56 patients with chronic periodontitis who were admitted in our hospital were included in the study and divided into the observation group and the control group according to different treatment protocols. The patients in the observation group were given self-ligating brackets, while the patients in the control group were given traditional brackets. The periodontal tissues and tooth motility (TM) before and after treatment in the two groups were observed and recorded. IL-1βand TNF-α levels in the gingival crervicular fluid (GCF) before and after treatment in the two groups were detected.Results:PD, CAL, SBI, and PLI after treatment in the two groups were significantly reduced, while GR was significantly elevated when compared with the control group. PD, CAL, SBI, and PLI after treatment in the observation group were significantly lower than those in the control group, while GR was significantly higher than that in the control group. TM after treatment in the two groups was significantly improved, among which the number of 0° TM was significantly increased, while the number ofⅠ°-Ⅲ°TM was significantly reduced. IL-1β and TNF-α levels in GCF after treatment in the two groups were significantly reduced when compared with before treatment. IL-1β and TNF-α levels in GCF after treatment in the observation group were significantly lower than those in the control group.Conclusions:The self-ligating brackets can effectively improve the periodontal tissues and TM in patients with chronic periodontitis, and reduce the levels of inflammatory cytokines in periodontal tissues, with an accurate efficacy.

Application Strategies of the Bracket Set in Modern Architectural Design

The Bracket Set(dougong)is an important aspect of traditional Chinese architecture known for its exquisite structure,complexity,and rich variations.This design element has been used since the Qin and Han Dynasties and is still prevalent today.It highlights hierarchy and spiritual connotations in the design of a building.This article explores the application of Bracket Set elements in modern architectural design.It analyzes the specific application strategies of this design element,highlighting its value in modern architecture.The goal is to provide modern architectural designers with multiple perspectives and strategies to fully utilize the advantages of Bracket Set elements in architectural design and enhance the artistic value of their work.

Research on semi-solid thixoforming process of AZ91D magnesium alloy brackets for generators in JH70-type motorbikes

The investment on semi-solid die casting processes of AZ91D magnesium alloy brackets for generators in JH70-type motorbikes is introduced. The processes of low super-heat and cooling slope for the preparation of billets with non-dendritic microstructure, the remelting of billets for thixoforming and the parameters in the process of semi-sohd thixoforming have been researched. The results show that primary billets with non-dendritical structures can be prepared by forming great amount of nuclei in melt via the process of low super heat. By optimizing the remelting process through adjusting the current of the induced equipment, semi-solid billets with a structure of spherical grains were obtained from the primary billets with non-dendritical structure. The range of 580℃ to 583℃ is the proper remelting temperatures by which the billets have an expected thixotropy and can be transferred to a die-casting machine. The optimized parameters of semi-solid forming in a die-casting machine are as follows： the area of the ingate in the die is 383.5 mm^2, the speed of the pierce of the machine 5 m/s, the shot pressure of the pierce 75 MPa, and the maintenance pressure of the pierce 350 MPa. The castings of brackets for supporting generators in JH70 type motorbikes were formed by adopting the optimized processes and parameters mentioned above.

The Evaluation of a Resin-modified Glass Ionome Cement for Bonding Orthodontic Brackets

To evaluate the shear bond strength（SBS） and bond failure interface after the debonding of orthodontic brackets with a resin-modified glass ionomer cement（RMGIC） under six bonding conditions, 140 premolar teeth were randomly divided into seven groups. The brackets of all groups, except for control group, were bonded using a RMGIC. The teeth were debonded using a universal testing machine. The shear bond strength, adhesive remnant index （ARI） and enamel fracture were examined for each debonding. A significant difference existed in SBS under wet and dry conditions in two groups of Fuji Ortho LC. Different degree of enamel fracture was seen in groups of Fuji Ortho LC（dry/37% phosphoric acid treated） after debonding. Bond failed predominantly at the enamel-adhesive interface, except for phosphoric acid treated groups. The RMGIC achieve a clinically effective adhesion in orthodontics under different bonding conditions.

Clinical assessment of demineralization and remineralization surrounding orthodontic brackets with FluoreCam

Objective: To determine quantitatively the amount of demineralization and the ability of commercially available products and an experimental cream to inhibit or reverse orthodontic related demineralization.Methods: A total of 20 patients who were 25–35 years old and having orthodontic treatment for 6–8 months were chosen.Caries risk assessments were done for each patient and ones with "moderate risk" were included.Patients with fixed orthodontic appliances were divided into 4 groups(5 patients each) including one control and 3 study groups.All patients used same toothpaste 2 times a day during the 3 weeks study period.Additional to the toothpaste first study group used MI Paste Plus(GC, Tokyo, Japan), second study group used Remin Pro(Voco, Cuxhaven, Germany) and third group used an experimental remineralizing cream per day for 3 weeks.Maxillary central and lateral incisors of each patient were examined by FluoreCam(Daraza Therametric Technologies, USA) device.The examinations were performed at baseline and at the end of 1st, 2nd and 3rd weeks.Results: According to the FluoreCam measurements the control group showed significant amount of demineralization at the end of 3 weeks, moreover the amount of demineralization has gradually increased in time.At the end of the study all 3 study groups showed significant amount of remineralization and the amount of remineralization for all the 3 study groups has gradually increased in time.However the amount of remineralization for 3rd study group was lesser than the 1st and 2nd study groups.The remineralization amounts for the 1st and 2 nd study groups were determined to be identical.Conclusions: This study demonstrated that demineralization is measurable around orthodontic brackets and the demineralization can be completely inhibited and/or reversed by the use of commercially available remineralization products.

External apical root resorption and the release of interleukin-6 in the gingival crevucular fluid induced by a self-ligating system

The aim of this study was to investigate the amount of external apical root resorption (EARR) and the release of interleukin (IL)-6 in the gingival crevicular fluid (GCF) in subjects treated with a low-force low-friction system. Sixty patients were assigned to two groups of thirty patients for each: one group received treatment with self-ligating brackets and the other with conventional ligated edgewise brackets. All patients were treated with extraction of the maxillary first premolars. The EARR of the maxillary central incisors was evaluated on the periapical radiographs and cephalograms, taken before and after orthodontic treatment. The GCF was also collected non-invasively from the mesial and distal sides of central incisors by using filter paper strips before and after orthodontic treatment. Enzyme-linked immunosorbent assay (ELISA) kits were used to determine the IL-6 levels in the GCF samples. A significant difference was found in the amount of EARR between the patients with self-ligating brackets and conventional brackets. The mean amount of EARR was significantly lower for self-ligating brackets than conventional brackets (p < 0.05). The GCF levels of IL-6 for the patients with self-ligating brackets appliance were significantly lower than for those with the conventional brackets (p < 0.05). These results show that the mean amount of EARR and the GCF levels of IL-6 were significantly lower in the patients treated using low-force low-friction appliances than conventional brackets. Therefore, self-ligating brackets may be a useful system for reducing inflammation and EARR.

Bond Strength of Brackets Bonded with Chemically and Light Activated Materials after Thermal Cycling

The aim of this study was to evaluate the bond strength of orthodontic brackets bonded to tooth enamel with different polymer composites after simulated clinical aging, and analyze the enamel/ bond system fracture interface. 80 human premolars, were randomly divided into five groups (n = 16). G1: CO (Concise Ortodontica—3M ESPE), G2: SB (SuperBond—Ortho Source), G3: FMO (Fill Magic Ortodontico—Vigodent), G4: TXT (Transbond XT—3M ESPE) and G5: TP (Transbond Plus Self Etching Primer + Transbond Plus Color Change—3M ESPE). In all groups, the metal orthodontic bracket was bonded to the tooth enamel surface. The specimens were submitted to 3000 thermal cycling baths for 30 s, at temperatures of 5°C, 37°C and 55°C (±1°C). Afterwards they were subjected to shear testing and the results were analyzed by the Student’s-t test (p < 0.05). G1 presented the highest bond strength value, followed by G4 > G5 > G2 > G3. In all groups the majority of the fractures at the interface of the specimens were cohesive, except in G3, which presented the largest number of adhesive fractures. After clinical aging, the chemically activated material (CO) showed higher bond strength than the light activated types (FMO, TXT and TP). The self-etching adhesive system (TP) showed similar bond strength to that of conventional systems (FMO and TXT).

Performance of Different Orthodontic Brackets after Exposure to Dietary Components: An <i>in Vitro</i>Pilot Study

Introduction: The aim of this study was to determine whether there was a significant difference in shear bond strength between metal and ceramic brackets when exposed to acidic dietary components (beverages) and to observe the chromogenic potential of each in vitro. Methods: Metal and clear orthodontic brackets were placed on extracted maxillary second premolars and exposed to select beverages three times daily for four weeks. Shade was taken using a colorimeter device at seven intervals and the shear bond strength of each bracket was recorded. Results: There was a variable change in tooth shade with respect to the various beverages in which they were submerged. Coffee and Dr. Pepper had the most pronounced change, whereas Red Bull and water produced little to none, respectively. Compared to controls, brackets submerged in coffee had the greatest reduction in shear bond strength, followed by Dr. Pepper, then Red Bull. Overall, clear brackets showed higher shear bond strength than metal brackets. Conclusion: Acidic dietary components have a negative effect on the shear bond strength of orthodontic brackets, and more pigmented beverages have a higher chromogenic staining potential.

A Study on the Multi-Objective Optimization Method of Brackets in Ship Structures

The shape and size optimization of brackets in hull structures was conducted to achieve the simultaneous reduction of mass and high stress,where the parametric finite element model was built based on Patran Command Language codes.The optimization procedure was executed on Isight platform,on which the linear dimensionless method was introduced to establish the weighted multi-objective function.The extreme processing method was applied and proved effective to normalize the objectives.The bracket was optimized under the typical single loads and design waves,accompanied by the different proportions of weights in the objective function,in which the safety factor function was further established,including yielding,buckling,and fatigue strength,and the weight minimization and safety maximization of the bracket were obtained.The findings of this study illustrate that the dimensionless objectives share equal contributions to the multi-objective function,which enhances the role of weights in the optimization.

Bonding Orthodontic Ceramic Brackets to Ceramic Restorations:Evaluation of Different Surface Conditioning Methods

The purpose of this study was to compare the shear bond strength and Adhesive Remnant Index of four different veneering ceramic materials to ceramic brackets. Additionallly, a further aim of this study was to overcome the etching using hydrofluoric acid which is noxious and could seriously damage the corneas of the eyes. Two surface conditioning methods of four ceramic materials before bonding brackets were examined: in group 1 an air particle abrasion with 25 μm aluminium trioxide (4 seconds at a pressure of 2.5 bars) and subsequently a silane coupling agent (Espe Sil, 3M Unitek, Monrovia, USA) was applicated on one side of each ceramic specimen (10 per group). In group 2 one side of each sample (20 per group) was etched with 37.0 per cent orthophosphoric acid for two minutes and was followed by a silane application (Espe Sil, 3M Unitek, Monrovia, USA). After this procedure the self-ligating ceramic brackets Clarity SL (3M Unitek, Monrovia, USA) brackets were bonded to the ceramic blocks and a thermocycling process started (5°C - 55°C, 6000 cycles). Then, shear bond strength and Adhesive Remnant Index (ARI) were measured. To determine statistical differences Oneway-ANOVA and Tukey Post-hoc test were performed. Hydrofluoric acid seems not to be justifiable anymore for preparing the surface of dental ceramic restorations before bracket bonding. Sandblasting with 25 μm aluminium trioxide and the use of orthophosphoric acid (37.0 per cent) seem to prepare the surface of ceramic restoration sufficiently before ceramic bracket bonding. The found level of shear bond strength values seems to be sufficient for bonding ceramic brackets to ceramic restorations.

Application of mobile photography with smartphone cameras for monitoring of orthodontic correction with dental BRACKETS

This research was to observe patients,who underwent orthodontic tooth alignment correction with dental brackets,for the purpose of early detection of white spots(early satge of caries)and dynamic measurement of distance between teeth edges based on the digital photographs taken with a smartphone Sony Xperia S.Color reading was realized taking into account the adjustment of color features of a standard ceramic surface(tile)that was selected during the dental brackets installation period,the photo of which was taken simultaneously during the dynamic observation period.The color scale RGB was transformed into CIE L*a*b scale of color measurement with regard to the correction of RGB components of image by usage of correction coefficient for calibration tile surface RGB characteristics.The expert appraisal showed sensitivity of proposed method was between 88.7%and 96.2%(the mean 93.1%)and specificity between 68.4%and 84.2%(the mean 75.4%).The positive predictive value was between 89.5%and94.0%(the mean 91.5%);and the negative predictive value was between 72.7%and 86.7%(the mean 80.6%).The measurement of the distance between teeth edges during the first 10 days following the brackets installation was carried out using a self-scalable ruler that was calibrated,according to the standard sizes of the dental bracket system components.The Android application of self-scalable ruler was developed using Java.The development of a pronounced pain syndrome was observed when the velocity of distance changes between teeth edges was rather high-0.051+0.004 mm/day.The improvement of efficiency of the suggested method is expected due to application of illumination standards during the shooting period.

出踩与面宽方向柱头科斗栱抗震性能对比试验及数值分析

为研究加载方向对斗栱抗震性能的影响,文章基于地震作用的随机性和斗栱出踩与面宽方向的构造差异,对2个足尺柱头科斗栱分别沿出踩和面宽方向进行拟静力试验,得到斗栱的破坏模式、承载力、刚度与强度退化、耗能和变形能力。结果表明:斗栱在出踩和面宽方向分别加载时,大斗均相对平板枋滑移,馒头榫挤压剪断。出踩方向受力时单昂与桃尖梁相对滑移,面宽方向受力时整体明显转动。相比面宽方向受力的斗栱,出踩方向受力的斗栱具有更高的承载力、初始刚度和耗能能力,而变形能力较差。文章开展柱头科斗栱的数值分析,模拟结果与试验结果吻合较好,研究出踩和面宽不同加载方向、轴压荷载、木构件之间摩擦系数和木材弹性模量对其抗震性能的影响。结果表明:面宽方向是柱头科斗栱的最不利受力方向,其正负向承载力比出踩方向分别低19.21%和17.03%;轴压荷载和木构件之间摩擦系数越大,斗栱承载力越大,而木材顺纹弹性模量和横纹径向弹性模量对斗栱的初始刚度和承载力影响较小。

无托槽隐形矫治器扩展上颌牙弓时附件差异对后牙位移的三维有限元分析

目的:利用全牙列精准扫描建模分析无托槽隐形矫治器扩展上颌牙弓时对后牙三维位移的影响。方法:选择2017年1月-2022年6月就诊于笔者医院口腔正畸科的86例成年患者为研究对象。所有患者均为安氏I类错牙合,矫治方案设计为仅通过邻面去釉的方式排齐上下前牙,在全牙列精准扫描建模的基础上,构建无托槽隐形矫治器进行上颌牙弓扩弓前以及扩弓后的后牙三维方向有限元模型的对比。结果:第5组位移量的最大值(3.315 17)与最小值(3.139 25)的比值均为所有组别中最小的。与其他组相比,第5组位移最小值与根尖的距离更近;第5组的第二前磨牙对应得到的等效应力值最小,应力的分布更为均匀。结论:施加附件作用时,对前磨牙的控根效果显著优于磨牙,其中优化后扩弓支持附件对后牙的控根效果更为优秀。

无褶皱吻合技术治疗结直肠恶性梗阻的应用价值

目的:探讨结直肠吻合新技术无褶皱吻合术治疗结直肠恶性梗阻的应用价值。方法:收集2020年1月至2022年12月收治的54例左半结肠直肠癌合并结直肠梗阻患者的临床资料。患者均为急诊就诊,确诊结直肠梗阻且腹部CT测量扩张肠管直径>30 mm。急症行内镜下经肛肠道自膨式金属支架置入术,术中取活检,病理结果证实恶性肿瘤。限期行腹腔镜结直肠癌切除术,术中应用无褶皱吻合技术进行一期吻合。术后随访7~24个月,评估吻合口相关并发症情况。结果:54例均完成腹腔镜结直肠癌切除术。术中测量近端肠管直径29.50~45.80 mm,平均(36.29±4.51)mm;远端肠管直径19.50~32.60 mm,平均(24.93±4.19)mm。近远端肠管管径不一致,行无褶皱吻合术,吻合放置抵钉座时间3~5 min,平均(3.80±0.79)min。术后无吻合口出血、狭窄、漏等并发症发生,术后随访未发生局部复发等远期并发症。结论:无褶皱吻合技术应用于结直肠恶性梗阻支架置入术后吻合确切,手术安全、可靠。

不锈钢支架熔模铸造工艺优化

通过ProCAST软件对除草机不锈钢支架进行熔模铸造的数值模拟,预测铸件缩孔缺陷分布情况,并对其浇注系统进行改善。利用正交试验对铸件的工艺参数进行研究,通过分析获得工艺参数的最佳方案。对该结果进行数值仿真以及实际铸造,发现铸件缺陷明显减少,这为不锈钢支架的生产提供了参考。

无托槽隐形矫治器治疗骨性Ⅱ类错[牙合]的疗效分析

目的 探讨无托槽隐形矫治器治疗骨性Ⅱ类错[牙合]的疗效。方法 以2021年7月至2023年10月在郑州大学第一附属医院进行正畸治疗的87例骨性Ⅱ类错[牙合]患者为研究对象开展回顾性分析,根据应用矫治器的不同分为传统组(应用传统固定矫治器治疗,n=44)和隐形组(应用无托槽隐形矫治器治疗,n=43)。比较两组矫治效果[采用美国正畸专家认证委员会(ABO)评级系统评定]、侧貌美学指标、牙周指数[探诊深度(PD)、菌斑指数(PLI)及牙龈指数(GI)]及龈沟液炎症因子[白细胞介素-1β(IL-1β)和可溶性细胞间黏附分子1(sICAM-1)]水平。结果 矫治后,隐形组ABO评级系统中的8项分值及总分与传统组比较,差异无统计学意义(P>0.05);矫治后,两组颌凸角、上下中切牙角、U1-PP、FMA、UL-EP、TLL-EP均优于矫治前(P<0.05),其中隐形组上下中切牙角、FMA优于传统组(P<0.05);矫治后,隐形组PD、PLI、GI及龈沟液IL-1β、sICAM-1水平均低于传统组(P<0.05)。结论 无托槽隐形矫治器可有效矫正骨性Ⅱ类错[牙合]畸形,提高患者侧貌美观度,并能减少对牙周组织的损害。

浅谈正畸临床矫治新技术——球托止动定位轻力5s系统

达成精确的转矩表达和稳定的支抗控制是正畸治疗的关键因素,患者在治疗过程中对口腔健康与矫治感受的重视程度日益增长,球面自锁托槽(球托)在一定程度上满足了这两个方面的需求。球面自锁托槽的球面结构可以降低因佩戴矫治器而引起口腔溃疡的概率,并能减少生物膜附着,降低牙龈和牙周疾病的发生概率。与方形托槽相比,球面自锁托槽的脱落率降低了95%。止动定位系统是球面自锁托槽的核心创新点,主要由螺纹系统、螺丝系统和弓丝系统组成。得益于止动定位系统,球面自锁托槽可以去除余隙角,精准表达转矩,使用止锁螺丝时可增强支抗稳定性。止动定位系统搭配了3种特制的细方丝(0.1524 mm×0.6350 mm、0.2032 mm×0.5842 mm、0.2540 mm×0.5588 mm),用轻力排齐的同时可以表达转矩,控制牙根。球托矫治器以黏膜刺激小、脱落率低、转矩表达精准、支抗保有率高、细方丝轻力矫治等特点引起了广泛关注。

基于改性PP成型的工控机电路板支撑架注射模设计

针对工控机电路板支撑架大型塑件的成型,选用了一种玻纤改性增强聚丙烯(PP)复合材料用于塑件的注射成型。模具结构为三板模结构,分3次开模打开。为保证塑件模腔充填均衡性、饱满性而设计了两个点浇口用于模腔的浇注。针对塑件二级子特征较多,特别是异型螺柱深筋位较多的特点,设计了多个局部镶件用于这些局部特征的成型,在提高局部成型镶件强度的同时,降低了这些成型件的加工难度。针对模腔局部位置排气难点,设置了多个透气镶件以增强排气。设置了锁扣机构、定距拉杆机构用于模具的开模闭模控制;设计了弹料机构用于流道废料的可靠脱模、定位机构以确保塑件的成型精度和模具工作寿命;3个滑块机构用于塑件侧壁直壁及直壁上侧孔的成型与脱模。模具结构形式合理,成型件便于加工且实用可靠,能为同类模具设计提供有益借鉴。

汽车变速器支架冲压成形工艺参数优化

该文以汽车变速器支架为研究对象,利用Dynaform软件研究其冲压成形过程出现的常见缺陷和问题。首先采用单因素分析确定正交试验的参数范围,然后通过正交试验和极差分析,获得各参数对最大减薄率的影响主次顺序,即冲压速度大于摩擦系数大于模具间隙;对于最大增厚率,冲压速度大于模具间隙大于摩擦系数,相对最优工艺参数组合为摩擦系数0.100、模具间隙1.44 mm、冲压速度1000 mm/s。最大减薄率的数值为15.345%、最大增厚率的仿真数值为16.017%,优化后的零件成形质量良好,可降低破裂的风险。

武汉青山长江公路大桥宽幅钢箱梁悬臂拼装横向线形匹配技术

武汉青山长江公路大桥主桥为主跨938 m的双塔双索面全飘浮体系斜拉桥,主跨整体式钢箱梁高4.5 m、全宽48 m,采用500 t架梁吊机分节段悬臂拼装架设。钢箱梁悬臂拼装时,架梁吊机站位节段、待架节段由于荷载及约束不同,横截面变形呈现出不同的趋势,线形匹配难度大。为解决该问题,主跨钢箱梁悬臂拼装时选择上、下游分体式架梁吊机,减少架梁吊机自重;经比选选择横桥向27.7 m间距的架梁吊机站位,减小了架梁吊机荷载对横向线形匹配的影响;通过设置顶压装置(由顶压牛腿、支承底座组成),在架梁吊机站位节段、待架节段钢箱梁边腹板处施加1500 kN顶压力,配合少量马板,一次加载完成对接口竖向变形匹配调整。施工后,钢箱梁横向线形匹配精度均满足要求。