A comparative in vitro study of frictional resistance between lingual brackets and stainless steel archwires

Friction between archwires and labial brackets has received considerable attention; however, information on the frictional behaviour of commercially available lingual brackets is limited. The aim of this study was to investigate the frictional resistance resulting from a combination of lingual orthodontic brackets (7th Generation, STb, Magic, and In-Ovation L) and stainless steel archwires at 0, 5, and 10 degrees of second-order angulation. Each bracket type (n = 30) was tested with three different sizes of archwires. Static and kinetic frictional forces were evaluated with a universal testing machine. Statistical analysis of the data was performed with non-parametric Kruskal-Wallis and Dunn's multiple comparison tests. All tested brackets showed higher frictional forces as the wire size and second-order angulation increased. The lowest friction was found with In-Ovation L brackets and 0.016 inch archwires at 0 degrees angulation, and the greatest friction with a combination of STb brackets and 0.017 × 0.025 inch archwires at 10 degrees angulation. For all combinations, Magic and In-Ovation L brackets showed lower frictional resistance when compared with 7th Generation and STb brackets. The slot width (occluso-gingival dimension) of the brackets, measured using the optics of a microhardness machine, showed that all brackets were oversized and that Magic brackets had the largest slot width. Surface roughness of the brackets investigated using atomic force microscopy and scanning electron microscopy, demonstrated that the 7th Generation brackets had the greatest surface roughness.     

人工唾液中直丝弓托槽与弓丝静摩擦力的实验研究

目的探讨人工唾液条件下,不同时间,几种直丝托槽与弓丝在后牙段的静摩擦力特点。方法在人工唾液条件下,4个时间段,测试4种直丝托槽与4种弓丝组合在后牙段的静摩擦力。结果0.46mm不锈钢圆丝的静摩擦力最小,0.48mm×0.64mm不锈钢方丝的静摩擦力最大。弓丝、托槽组合在人工唾液条件下作用15d静摩擦力最大、30d静摩擦力最小。结论0.46mm不锈钢圆丝的静摩擦力最小;人工唾液作用30d静摩擦力最小。     

湿润状态下托槽与弓丝间动摩擦力的实验研究

目的:探究人工唾液条件下不同时间,几种直丝托槽与弓丝在后牙段的动摩擦力状况.方法:在人工唾液条件下,4个时间段:0、15、30、45 d,使用Instron万能材料力学实验机,模拟弓丝在后牙段滑动,按正交设计测试4种直丝托槽与4种弓丝组合在后牙段的动摩擦力.结果:3M MBT托槽的动摩擦力最小,0.48mm×0.64哪方丝的动摩擦力最大,0.46 mm圆丝的动摩擦力最小.弓丝、托槽组合在人工唾液条件下作用15 d动摩擦力最大、30 d动摩擦力最小.结论:0.46 mm圆丝的动摩擦力最小;人工唾液作用30 d动摩擦力最小;3M MBT托槽比较适合于滑动法关闭问隙.     

彩色不锈钢托槽和弓丝的摩擦力实验

目的研究新型的彩色弓丝和托槽染色前后摩擦性状有无改变。方法将通过化学着色法得到的彩色不锈钢托槽、弓丝与常用的托槽、弓丝两两交叉分为四组(无色丝-无色槽、无色丝-有色槽、有色丝-无色槽、有色丝-有色槽)与5种尺寸(0.016、0.018、0.017×0.025、0.018×0.025、0.019×0.025英寸)弓丝结合,测试干燥状态下的静摩擦力。结果不论圆丝或方丝,各弓丝、托槽组合间摩擦力没有显著性差异。不锈钢圆丝的摩擦力小于方丝。结论化学着色对弓丝、托槽的摩擦力没有影响。     

Corrosion of metal orthodontic brackets and archwires caused by fluoride-containing products: Cytotoxicity,metal ion release and surface roughness

Purpose

The aims of this study were to determine the cytotoxicity, metal ion release and surface roughness of metal orthodontic appliances after immersion in different fluoride product solutions.

Role of lubricants on friction between self-ligating brackets and archwires

Objective:To evaluate the effect of different lubricants on friction between orthodontic brackets and archwires.Materials and Methods:Active (Quick, Forestadent) and passive (Damon 3MX, Ormco) self-ligating brackets underwent friction tests in the presence of mucin- and carboxymethylcellulose (CMC)–based artificial saliva, distilled water, and whole human saliva (positive control). Dry friction (no lubricant) was used as the negative control. Bracket/wire samples (0.014 × 0.025 inch, CuNiTi, SDS Ormco) underwent friction tests eight times in a universal testing machine.Results:Two-way analysis of variance showed no significant interaction between bracket type and lubricant (P  =  .324). Friction force obtained with passive self-ligating brackets was lower than that for active brackets (P < .001). Friction observed in the presence of artificial saliva did not differ from that generated under lubrication with natural human saliva, as shown by Tukey test. Higher friction forces were found with the use of distilled water or when the test was performed under dry condition (ie, with no lubricant).Conclusion:Lubrication plays a role in friction forces between self-ligating brackets and CuNiTi wires, with mucin- and CMC-based artificial saliva providing a reliable alternative to human natural saliva.     

Characterization of the coatings covering esthetic orthodontic archwires and their influence on the bending and frictional properties

Objective:To analyze the coatings covering esthetic orthodontic wires and the influence of such coatings on bending and frictional properties.Materials and Methods:Four commercially available, coated esthetic archwires were evaluated for their cross-sectional dimensions, surface roughness (R_a), nanomechanical properties (nanohardness, nanoelastic modulus), three-point bending, and static frictional force. Matched, noncoated control wires were also assessed.Results:One of the coated wires had a similar inner core dimension and elasticity compared to the noncoated control wire, and no significant differences between their static frictional forces were observed. The other coated wires had significantly smaller inner cores and lower elasticity compared to the noncoated wires, and one of them showed less static frictional force than the noncoated wire, while the other two coated wires had greater static frictional force compared to their noncoated controls. The dimension and elastic modulus of the inner cores were positively correlated (r = 0.640), as were frictional force and total cross-sectional (r = 0.761) or inner core (r = 0.709) dimension, elastic modulus (r = 0.777), nanohardness (r = 0.802), and nanoelastic modulus (r = 0.926). The external surfaces of the coated wires were rougher than those of their matched controls, and the R_a and frictional force were negatively correlated (r = −0.333).Conclusions:Orthodontic coated wires with small inner alloy cores withstand less force than expected and may be unsuitable for establishing sufficient tooth movement. The frictional force of coated wires is influenced by total cross-section diameter, inner core diameter, nanohardness, nanoelastic modulus, and elastic modulus.     

口腔正畸托槽与弓丝之间最大静摩擦力与静摩擦系数的实验研究

目的 设计一种体外装置,研究正畸托槽与弓丝之间的最大静摩擦和静摩擦系数.方法 实验选择了一种方丝托槽与两种直径0.4 mm的正畸钢丝,设计实验装置在干燥和有唾液条件下测量托槽与弓丝之间在不同正压力下的最大静摩擦力和静摩擦系数.结果 研究发现,在干燥条件下,国产弓丝与托槽之间产生的最大静摩擦力和静摩擦系数显著大于3 M弓丝,在有唾液时两者无显著区别.结论 不同条件下,弓丝与托槽之间产生的静摩擦力与静摩擦系数不同.     

Effect of remineralizing agents on bond strength of orthodontic brackets: an in vitro study

Background

The purpose of this study is to evaluate the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) and CPP-ACP with fluoride (CPP-ACP-F) on the shear bond strength (SBS) of orthodontic brackets bonded with two different adhesive systems.

Methods

One hundred twenty-six human premolar teeth were selected. One hundred twenty teeth were used for SBS testing, and six teeth were used for scanning electron microscope (SEM) examination. One hundred twenty premolars were divided into mainly three groups: CPP-ACP (group A), CPP-ACP-F (group B), and control group (group C). Each group was sub-divided into two groups according to the bonding adhesive, light cure (groups A1, B1, and C1) and chemical cure (groups A2, B2, and C2). The teeth were pre-treated with the group-specified preventive agent 1 h/day for five consecutive days. Standard edgewise brackets were bonded with the respective adhesives. SBS evaluation was done with the universal testing machine. After debonding, all the teeth were scored for adhesive remaining on the buccal surface, in accordance to adhesive remnant index, under a stereomicroscope. The acid-etched enamel surfaces were observed under SEM after treatment with CPP-ACP, CPP-ACP-F, and artificial saliva.

Result

In light-cure adhesive group, CPP-ACP-F (B1) showed superior results compared to the control group (C1), whereas the CPP-ACP group (A1) showed lower mean SBS than the control group (C1). Both these differences were not statistically significant (p > 0.05). In chemical-cure adhesive group, control group C2 showed significantly superior results (p < 0.05) compared to group A2 and group B2. The results of two-way ANOVA showed highly significant difference due to adhesive types (p < 0.01), whereas enamel pre-treatment showed non-significant difference (p > 0.01).

Conclusion

The SBS of the orthodontic brackets was non-significantly affected when the brackets were cured with light-cure bonding system and treated with either CPP-ACP or CPP-ACP-F, whereas with chemical-cure adhesive, decreased bond strength was seen, which was within the clinically acceptable limits.     

A comparative study of the static and kinetic frictional resistance of titanium molybdenum alloy archwires in stainless steel brackets

This ex vivo study compared the static and kinetic frictional resistance of eight different archwires tested in a single, stainless steel, zero base 0.022 x 0.028 inch (0.56 x 0.711 mm) slot standard edgewise bracket. The archwires evaluated were 0.019 x 0.025 inch (0.483 x 0.636 mm) in dimension, manufactured from the following alloys: beta titanium (TMA), 'low friction' coloured beta titanium (aqua, honeydew, purple and violet), ion-implanted beta titanium, Timolium and a stainless steel control. Prior to friction testing, bracket and archwire dimensions were measured by direct digital imaging via a desktop computer linked to a binocular light microscope. Frictional force was evaluated using an Instron universal testing machine. All experiments were carried out at room temperature, with no ligation, in the dry state with 20 degrees of added torque. The results demonstrated that static and kinetic friction were statistically significant (P < 0.001) for all archwire types. Ion-implanted and standard TMA archwires were found to have no significant advantage over stainless steel. The archwire alloys may be ranked as follows: stainless steel produced the lowest frictional resistance followed by honeydew, ion-implanted TMA and Timolium, with aqua, purple and violet producing frictional resistance values as high as standard TMA. It was also found that the percentage difference between the archwire and bracket slot dimensions claimed by the manufacturers and those measured in this experiment produced tolerances ranging from +5.37 to -6.67 per cent.     

国产LF托槽与进口TOMY托槽脱落率及黏膜损伤的对比研究

目的对比研究LF托槽和进口TOMY托槽的托槽脱落率和黏膜损伤情况。方法正畸患者80例,LF组40例,粘接LF托槽800颗;TOMY组40例,粘接TOMY自锁托槽800颗,2组采用相同的方法和步骤进行粘接。每个月复诊时记录托槽脱落情况和创伤性口炎的发生情况,连续观察1年。结果 LF组的托槽脱落率为8.38%(67/800),TOMY组的托槽脱落率为8.00%(64/800),2组托槽脱落率差异没有统计学意义(χ2=51.8,P=0.10)。LF组创伤性口炎总发病率为97.5%(39/40),TOMY组总发病率为50.0%(20/40),LF组高于TOMY组,差异有统计学意义(χ2=63.7,P=0.01)。结论国产LF托槽和进口TOMY托槽的脱落率相近,但国产LF托槽引起创伤性口炎的概率更高。     

Comparison of static friction and surface topography of low friction and conventional TMA orthodontic arch wires: An in-vitro study

BackgroundArch wire surface characteristics, especially surface roughness and topography, influence the coefficient of friction during sliding. The clinician should be familiar with the properties of orthodontic appliances and materials that could result in high friction to maximize the efficiency of treatment. This study aimed to compare the static friction of orthodontic arch wire materials, including a newly introduced low-friction TMA, conventional TMA, and stainless steel arch wires, using an Instron universal testing machine and to evaluate their surface topographical features using a noncontact optical profilometer.MethodsA total of 30 arch wire specimens were used, including 10 low-friction TMA (TMA-Low), 10 conventional TMA (TMA-C), and 10 stainless steel (SS), (Ormco, Orange, CA, USA) measuring 0.016 × 0.022 in. The static frictional force of each arch wire material was measured using the universal Instron machine. The surface topography was evaluated using a noncontact profilometer machine.ResultsThe static frictional resistance forces were highest in the TMA-C alloy group, and the value was statistically significant in comparison to the SS arch wire but not to the TMA-Low arch wire. The mean value of the static friction of the TMA-Low group was intermediate between the TMA-C and SS arch wires. However, this difference was statistically insignificant compared to the other two alloys. A surface roughness evaluation using a profilometer machine revealed that the highest mean of all three roughness parameters was found in the TMA-C group, followed by the TMA-Low and SS arch wires in descending order.ConclusionThe static friction resistance forces and surface roughness values of the TMA-Low arch wire are comparable to those of TMA-C but are still considered inferior to those of the SS arch wire.     

不同尺寸、不同摇椅曲度不锈钢方丝在Empower自锁托槽内摩擦力的实验分析

目的 研究不同尺寸、不同摇椅曲度(rocking chair curvature,RCC)不锈钢方丝（stainless steel,SS）在Empower自锁托槽(Empower self-ligating brackets,Empower SLB)内所产生的摩擦力差异。方法 选用由标准石膏模型翻制的标准牙〖HT5”,7”SS〗牙〖KG-*3〗合模型,并于干燥条件下在其上粘结Empower SLB及颊面管,分别测量按照在电镜下确定弓丝拉拔方向的两种尺寸SS(0.46 mm×0.64 mm、0.48 mm×0.64 mm),4种不同RCC(0°、5°、10°、15°),共8种弓丝-摇椅工况组合在滑动法关闭拔牙间隙时在Empower SLB内产生的摩擦力。结果 两种尺寸弓丝分别在尖牙至第二前磨牙区加载0°、5°、10°、15°的RCC,得出以下结果：①所有工况下动摩擦力稍小于最大静摩擦力;②相同RCC下,0.46 mm×0.64 mm SS 在自锁托槽内产生的滑动摩擦力小于0.48 mm×0.64 mm SS（P＜0.05);③相同尺寸弓丝随RCC（0°、5°、10°、15°）增加,滑动摩擦力（0.46 mm×0.64 mm SS :0＜0.19 N＜0.35 N＜0.90 N;0.48 mm×0.64 mm SS:0＜0.26 N＜0.43 N＜1.00 N）逐渐增大（P＜0.05)。结论 SS在Empower SLB内的滑动摩擦力稍小于最大静摩擦力,弓丝尺寸越大、摇椅曲曲度越大,SS在自锁托槽内产生的摩擦力也越大。     

脱落托槽热处理后对摩擦力影响的实验研究

目的测试热处理对托槽与弓丝间最大静摩擦力的影响。方法在干燥条件下,选取0.022×0.028英寸上颌尖牙不锈钢直丝托槽36枚,弓丝为0.019×0.025英寸不锈钢方丝。将36枚托槽随机分成三组,每组12枚,第一组不做任何处理,第二组、第三组托槽背板粘一薄层京津釉质粘结剂,热处理后用探针去除粘结剂,第三组托槽再进行超声清洗5分钟,分别测试这三组托槽与弓丝间最大静摩擦力。结果测得未经处理的上颌尖牙托槽与0.019×0.025英寸弓丝间最大静摩擦力值为74.67±12.73g;热处理及热处理后经超声清洗的托槽与弓丝间最大静摩擦力值分别是66.31±12.44g、61.97±13.47g。结论热处理及热处理后经超声清洗的托槽与弓丝间产生的最大静摩擦力值较未经任何处理的托槽与弓丝间产生的最大静摩擦力值明显减小。     

Effect of argon laser irradiation on shear bond strength of orthodontic brackets: an in vitro study.

Argon lasers, due to their significant time savings over conventional curing lights, are being investigated for use in bonding orthodontic brackets. They are also being investigated for their ability to confer demineralization resistance on enamel. The purpose of this study was to evaluate the effects of argon laser irradiation on bond strength at 3 different laser energies (200, 230, and 300 mW) and at 3 unique time points of laser application (before, during, or after bracket placement). One hundred-fifty human posterior teeth were divided into 9 study groups and 1 control group. After debonding, the adhesive remnant index was scored for each tooth. There was no evidence of an effect of energy level on bond strength, P =.903, or of an interaction between timing of bracket placement and energy level, P =.858. When combining data across energy levels, the mean bond strength was significantly different between all 3 bracket placement groups, P <.001. In addition, the mean bond strength of teeth lased after bonding was significantly higher than the control group, P <.05. There were no statistically significant differences between adhesive remnant index scores among the 10 groups. Lasing the enamel before or after bonding does not adversely affect bond strength. Use of the argon laser to bond orthodontic brackets can yield excellent bond strengths in significantly less time than conventional curing lights, while possibly making the enamel more resistant to demineralization.     

The effect of argon laser irradiation on demineralization resistance of human enamel adjacent to orthodontic brackets: an in vitro study

Argon lasers, because of their significant timesavings over conventional curing lights, have been investigated for use in bonding orthodontic brackets. They are also being investigated for their ability to confer demineralization resistance on enamel, which is of great interest in orthodontics. A two-part in vitro study on 86 human posterior teeth was conducted to determine the effects of a five-second argon laser exposure on shear bond strength and to evaluate the effects of a five- and 10-second argon laser exposure (250 mW) on demineralization of enamel surrounding orthodontic brackets after exposure to an artificial caries bath. Brackets cured with the argon laser for five seconds yielded mean bond strengths similar to those attained with a 40-second conventional light-cured control (n = 13 per group, 20.4 vs 17.8 MPa). Brackets cured with the argon laser for 10 seconds resulted in significantly lower mean lesion depth when compared with a visible light control (n = 20 per group, 107.8 vs 137.2 microm, P = .038). There were no statistically significant differences in lesion depth between the five-second argon laser and the visible light control groups. Overall, there was a 15% and 22% reduction in lesion depths for the five- and 10-second group, respectively. Poor correlations were found between the clinical appearance of decalcifications and their lesion depth. Argon lasers used for bonding orthodontic brackets would save a significant amount of chair time while possibly conferring demineralization resistance upon the enamel.