自制美学涂层弓丝表面形貌的研究

目的：对自制美学涂层弓丝表面粗糙度进行测试,并与传统不锈钢弓丝进行比较,在扫描电镜下观察弓丝的表面形貌。方法：分别测定经4种托槽（带金属槽沟的陶瓷托槽,普通托槽,陶瓷托槽,树脂托槽）摩擦过的及未经摩擦的0.018英寸的美学涂层不锈钢圆丝和0.018英寸的不锈钢圆丝的表面粗糙度,并在扫描电镜下观察弓丝的形貌特征。结果：未经摩擦过的涂层与未涂层弓丝间的表面粗糙度比较,无统计学意义;经托槽摩擦过的涂层与未涂层弓丝间的表面粗糙度比较,有统计学意义,且与不同托槽摩擦后弓丝表面粗糙度值不同,其中,与陶瓷托槽摩擦后的弓丝表面粗糙度和与带金属槽沟的陶瓷托槽,普通托槽及未摩擦的弓丝表面粗糙度存在统计学差异。结论：美学涂层弓丝符合口腔正畸临床使用要求。     

The effects of reconditioning on the slot dimensions and static frictional resistance of stainless steel brackets

This study investigated the effects of reconditioning on the slot dimensions and the static frictional resistance of stainless steel brackets at 0, 5, and 10 degrees bracket/archwire angulation. A sample of 45 used, commercially reconditioned 0.018 x 0.030 inch stainless steel standard edgewise brackets was compared with a matched sample of 45 new brackets. The slot dimensions of 15 new and 15 reconditioned brackets were examined using a photomicroscope. With new brackets both the occluso-gingival slot width (mean = 0.0197 inch) and slot depth (mean = 0.0304 inch) exceeded the manufacturer's nominal dimensions of 0.018 x 0.030 inch. The reconditioning process resulted in a further increase in slot width (mean = 0.0205 inch), which was statistically significant (P = 0.028), and a reduction in slot depth (mean = 0.0291 inch), which was highly statistically significant (P = 0.002). This may be attributable to preferential metal removal by the electro-polishing phase of the reconditioning process. Friction testing of 30 new and 30 reconditioned brackets demonstrated that both showed an increase in binding effects as the bracket/archwire angulation was increased from 0 to 5-10 degrees. However, the changes in slot dimensions secondary to reconditioning did not result in a statistically significant difference in mean static frictional resistance when the two bracket types were compared. Although the brackets were altered physically by the reconditioning process, their performance during simulated sliding mechanics was not adversely affected. This implies that reconditioning may not result in clinically significant effects.     

Evaluation of titanium brackets for orthodontic treatment: Part II--The active configuration.

After each archwire was ligated into a bracket with a 0.010-in stainless steel wire, both stainless steel and beta-titanium archwires (0.017- x 0.025-in) were slid through commercially pure titanium brackets (0.018-in slot size) at 34 degrees C in both the dry and wet conditions. As controls, stainless steel archwire versus stainless steel bracket couples were used with comparable dimensions. The drawing forces were measured at 5 angulations (0 degrees, 3 degrees, 7 degrees, 9 degrees, and 11 degrees ) for 5 normal forces (nominally 0.2, 0.4, 0.6, 0.8, and 1.0 kg). Regression lines were determined for each frictional couple (P <.05). In the passive configuration, the kinetic frictional coefficients of control and test couples in the dry condition were comparable to previously reported values at 0.11 +/- 0.01 for stainless steel versus stainless steel, 0.12 +/- 0.00 for stainless steel versus titanium, and 0.26 +/- 0.02 for beta-titanium versus titanium. As the angulation was increased from 0 degrees to 11 degrees and the normal force was maintained at 0.2 kg, the resistance to sliding values increased by 208 g for stainless steel versus stainless steel, by 222 g for stainless steel versus titanium, and by 185 g for beta-titanium versus titanium. When the normal force was increased to 1.0 kg, the resistance to sliding values increased to 277 g, 246 g, and 245 g, respectively. Although resistance to sliding increased with angulation and normal force, the passive layer did not breakdown. Titanium brackets remained comparable to stainless steel brackets in the active configuration.     

Evaluation of friction of stainless steel and esthetic self-ligating brackets in various bracket-archwire combinations.

This study measured and compared the level of frictional resistance generated between stainless steel self-ligating brackets (Damon SL II, SDS Ormco, Glendora, Calif), polycarbonate self-ligating brackets (Oyster, Gestenco International, G?thenburg, Sweden), and conventional stainless steel brackets (Victory Series, 3M Unitek, Monrovia, Calif), and 3 different orthodontic wire alloys: stainless steel (Stainless Steel, SDS Ormco), nickel-titanium (Ni-Ti, SDS Ormco), and beta-titanium (TMA, SDS Ormco). All brackets had a.022-in slot, whereas the orthodontic wire alloys were tested in 3 different sections:.016,.017 x.025, and.019 x 0.025 in. Each of the 27 bracket and archwire combinations was tested 10 times, and each test was performed with a new bracket-wire sample. Both static and kinetic friction were measured on a custom-designed apparatus. All data were statistically analyzed (Kruskal-Wallis and Mann Whitney U tests). Stainless steel self-ligating brackets generated significantly lower static and kinetic frictional forces than both conventional stainless steel and polycarbonate self-ligating brackets, which showed no significant differences between them. Beta-titanium archwires had higher frictional resistances than stainless steel and nickel-titanium archwires. No significant differences were found between stainless steel and nickel-titanium archwires. All brackets showed higher static and kinetic frictional forces as the wire size increased.     

Torque Expression in Stainless Steel Orthodontic Brackets: A Systematic Review

Objective:To evaluate the quantitative effects on torque expression of varying the slot size of stainless steel orthodontic brackets and the dimension of stainless steel wire, and to analyze the limitations of the experimental methods used.Materials and Methods:In vitro studies measuring torque expression in conventional and self-ligating stainless steel brackets with a torque-measuring device, with the use of straight stainless steel orthodontic wire without second-order mechanics and without loops, coils, or auxiliary wires, were sought through a systematic review process.Results:Eleven articles were selected. Direct comparison of different studies was limited by differences in the measuring devices used and in the parameters measured. On the basis of the selected studies, in a 0.018 inch stainless steel bracket slot, the engagement angle ranges from 31 degrees with a 0.016 × 0.016 inch stainless steel archwire to 4.6 degrees with a 0.018 × 0.025 inch stainless steel archwire. In a 0.022 inch stainless steel bracket slot, the engagement angle ranges from 18 degrees with a 0.018 × 0.025 inch stainless steel archwire to 6 degrees with a 0.021 × 0.025 inch stainless steel archwire. Active stainless steel self-ligating brackets demonstrate an engagement angle of approximately 7.5 degrees, whereas passive stainless steel self-ligating brackets show an engagement angle of approximately 14 degrees with 0.019 × 0.025 inch stainless steel wire in a 0.022 inch slot.Conclusions:The engagement angle depends on archwire dimension and edge shape, as well as on bracket slot dimension, and is variable and larger than published theoretical values. Clinically effective torque can be achieved in a 0.022 inch bracket slot with archwire torsion of 15 to 31 degrees for active self-ligating brackets and of 23 to 35 degrees for passive self-ligating brackets with a 0.019 × 0.025 inch stainless steel wire.     

Quantified simulation of canine retraction: evaluation of frictional resistance

The purpose of this study was to evaluate the frictional resistance of various bracket/archwire combinations. The friction testing apparatus allowed dynamic and progressive bracket tipping and uprighting concurrent with linear bracket traction which experimentally approximated canine retraction with sliding mechanics. Multiple ANOVA using general linear models procedure demonstrated significant effects (P < 0.05) for bracket type, archwire type, archwire size, and archwire shape, as well as pair-wise interactions for bracket type/archwire type, bracket type/archwire size, bracket type/archwire shape, archwire type/archwire size, archwire type/archwire shape, and archwire size/archwire shape. Duncan’s multiple range test (P < 0.05) revealed the general trends regarding frictional performance of brackets and archwires tested, while Least squares means table (P < 0.05) illustrated significant interactions of pair-wise factors that differed from the general trends. It was concluded that: (1) Ceramic brackets with and without metal slots had the greatest friction followed by metal brackets, active self-ligating brackets, variable self-ligating brackets, and passive self-ligating brackets. (2) Stainless steel and braided stainless archwires measured greater friction than nickel-titanium. (3) Smaller dimension wires had less friction than larger wires, and round wires had less friction than rectangular wires. In addition, consideration of specific bracket-archwire coupling appear to reduce the frictional resistance with sliding.     

A comparison of self-ligating and conventional orthodontic bracket systems.

Abstract

This ex-vivo study compared the static frictional resistance of three self-ligating brackets with a conventional steel-ligated Ultratrimm bracket. The effects of archwire size (0.020, 0.019 x 0.025 and 0.021 x 0.025-inch), bracket/archwire angulation (0, 5 and 10 degrees) and the presence of unstimulated human saliva were investigated. The study demonstrated that both increases in wire size and bracket/archwire angulation resulted in increased static frictional resistance for all bracket types tested, with the presence of saliva having an inconsistent effect. Mobil-Lock Variable-Slot had the least friction for all wires for 0 degree angulation. However, with the introduction of angulation, the values were comparable to those of the other brackets. Activa brackets had the second lowest frictional resistance, although high values were found with 0.019 x 0.025-inch wires. SPEED brackets demonstrated low forces with round wires, although with rectangular wires or in the presence of angulation, friction was greatly increased. Ultratrimm brackets produced large individual variation, confirming the difficulty in standardizing ligation force, although under certain conditions, significantly larger frictional forces were observed. In conclusion, self-ligating brackets showed reduced frictional resistance in comparison to steel ligated brackets only under certain conditions.     

自锁托槽对关闭拔牙间隙阶段滑动阻力的影响

目的 比较在牙齿关闭拔牙间隙过程中不同自锁托槽和传统托槽与不锈钢丝组合所产生的滑动阻力。方法 在干燥环境下,分别选择2种自锁托槽(被动Damon^®和主动Tomy^®)和传统托槽的2种结扎方式(橡皮结扎圈和结扎丝)与0.019×0.025英寸不锈钢丝组合,测量严重牙列拥挤患者在拔牙后排齐整平的下颌模型上关闭拔牙间隙阶段的滑动阻力。采用方差分析的方法对各项测量数据进行统计学处理。结果 在关闭拔牙间隙阶段,不同托槽组合、组间的滑动阻力的差异均具有显著的统计学意义(P<0.01),最大静摩擦力和滑动摩擦力由小到大依次为被动Damon组<主动Tomy组<结扎丝结扎组<结扎圈结扎组。结论 在关闭拔牙间隙阶段,被动自锁托槽的滑动阻力明显小于主动自锁托槽的滑动阻力,自锁托槽的滑动阻力明显小于传统托槽的滑动阻力。     

Evaluation of titanium brackets for orthodontic treatment: Part II—The active configuration

After each archwire was ligated into a bracket with a 0.010-in stainless steel wire, both stainless steel and beta-titanium archwires (0.017- × 0.025-in) were slid through commercially pure titanium brackets (0.018-in slot size) at 34° C in both the dry and wet conditions. As controls, stainless steel archwire versus stainless steel bracket couples were used with comparable dimensions. The drawing forces were measured at 5 angulations (0°, 3°, 7°, 9°, and 11°) for 5 normal forces (nominally 0.2, 0.4, 0.6, 0.8, and 1.0 kg). Regression lines were determined for each frictional couple (P < .05). In the passive configuration, the kinetic frictional coefficients of control and test couples in the dry condition were comparable to previously reported values at 0.11 ± 0.01 for stainless steel versus stainless steel, 0.12 ± 0.00 for stainless steel versus titanium, and 0.26 ± 0.02 for beta-titanium versus titanium. As the angulation was increased from 0° to 11° and the normal force was maintained at 0.2 kg, the resistance to sliding values increased by 208 g for stainless steel versus stainless steel, by 222 g for stainless steel versus titanium, and by 185 g for beta-titanium versus titanium. When the normal force was increased to 1.0 kg, the resistance to sliding values increased to 277 g, 246 g, and 245 g, respectively. Although resistance to sliding increased with angulation and normal force, the passive layer did not breakdown. Titanium brackets remained comparable to stainless steel brackets in the active configuration. (Am J Orthod Dentofacial Orthop 2000;118:675-84)     

自制美学涂层弓丝摩擦力的实验研究

目的：对自制美学涂层弓丝的摩擦力进行测试,并与普通不锈钢弓丝比较。方法：在干燥条件下,模拟临床牙齿移动,分别测定0．018″美学涂层不锈钢圆丝和0．018″普通不锈钢圆丝与3种美学托槽（陶瓷托槽、树脂托槽、带金属槽沟的陶瓷托槽）组合的摩擦力并进行比较。同时比较与美学涂层弓丝组合时,3种托槽之间的摩擦力大小。结果：在与3种美学托槽组合时,美学涂层不锈钢圆丝与普通不锈钢圆丝的摩擦力虽有不同,但无显著性差异。3种美学托槽与美学涂层弓丝组合时,陶瓷托槽的摩擦力明显大于树脂托槽和带金属槽沟的陶瓷托槽,而后两者之间无统计学差异。结论：此种美学涂层弓丝符合口腔正畸临床使用要求。     

Torque capacity of metal and polycarbonate brackets with and without a metal slot

The aim of the present study was to investigate slot deformation and the equivalent torque capacity of polycarbonate brackets with and without a metal slot in comparison with those of a metal bracket. For this purpose, the expansion characteristics and, in a further investigation, the labial crown torque of an upper central incisor, were measured in a simulated intra-oral clinical situation, using the orthodontic measuring and simulation system (OMSS). Three types of bracket with a 0.018 inch slot were tested: polycarbonate Brillant without a metal slot, Elegance with a metal slot and the metal bracket, Mini-Mono. For testing purposes the brackets were torqued with 0.016 x 0.022 inch (0.41 x 0.56 mm) and 0.018 x 0.022 inch (0.46 x 0.56 mm) ideal stainless steel archwires. In the activating experiments, significantly higher torque losses and lower torquing moments were registered with both rectangular archwires with the polycarbonate brackets than with the metal bracket. In the simulation tests, significantly higher torquing moments were registered with the metal bracket than with the polycarbonate brackets. The values for the Elegance bracket were between those of the Mini-Mono and Brillant brackets. The OMSS model approximates the clinical situation, with the torque loss being notably higher than in the in vitro activating experiments. This is due to the adjacent teeth giving the archwire additional play. In addition, the torquing process may twist the archwire, resulting in subsidiary forces. On the basis of the present results, all three brackets can be recommended for torquing. However, in view of the high torque losses, the torques programmed in the straightwire technique must be seen as questionable. Data should be provided by the manufacturer on the bending to be expected in polycarbonate brackets, which has to be offset by additional torque, or the bracket torque should be omitted from the technical specifications.     

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.     

Effect of chlorhexidine-containing prophylactic agent on the surface characterization and frictional resistance between orthodontic brackets and archwires: an in vitro study

Background

The purpose of this study was to assess the surface characterization and frictional resistance between stainless steel brackets and two types of orthodontic wires made of stainless steel and nickel-titanium alloys after immersion in a chlorhexidine-containing prophylactic agent.

Methods

Stainless steel orthodontic brackets with either stainless steel (SS) or heat-activated nickel-titanium (Ni-Ti) wires were immersed in a 0.2% chlorhexidine and an artificial saliva environment for 1.5 h. The frictional force was measured on a universal testing machine with a crosshead speed of 10 mm/min over a 5-mm of archwire. The surface morphology of bracket slots and surface roughness of archwires after immersion in chlorhexidine were also characterized using a scanning electron microscope (SEM) and an atomic force microscope (AFM), respectively.

Results

There was no significant difference in the frictional resistance values between SS and Ni-Ti wires immersed in either chlorhexidine or artificial saliva. The frictional resistance values for the SS and Ni-Ti wires immersed in 0.2% chlorhexidine solution were not significantly different from that inartificial saliva. No significant difference in the average surface roughness for both wires before (as-received) and after immersion in either chlorhexidine or artificial saliva was observed.

Conclusions

One-and-half-hour immersion in 0.2% chlorhexidine mouthrinse did not have significant influence on the archwires surface roughness or the frictional resistance between stainless steel orthodontic brackets and archwires made of SS and Ni-Ti. Based on these results, chlorhexidine-containing mouthrinses may be prescribed as non-destructive prophylactic agents on materials evaluated in the present study for orthodontic patients.     

In vitro evaluation of frictional forces between archwires and ceramic brackets.

The aim of this study was to evaluate the frictional force between orthodontic brackets and archwires. The differences in magnitude of the frictional forces generated by ceramic brackets, ceramic brackets with metal reinforced slot, and stainless steel brackets in combination with stainless steel, nickel-titanium, and beta-titanium orthodontic archwires were investigated. Brackets and wire were tested with tip angulations of 0 degrees and 10 degrees. Friction testing was done with the Emic DL 10000 testing machine (S?o José do Rio Preto, PR, Brazil), and the wires were pulled from the slot brackets with a speed of 0.5 cm/min for 2 minutes. The ligation force between the bracket and the wire was 200 g. According to the data obtained, the brackets had frictional force values that were statistically significant in this progressive order: stainless steel bracket, ceramic bracket with a metal reinforced slot, and traditional ceramic bracket with a ceramic slot. The beta-titanium wire showed the highest statistically significant frictional force value, followed by the nickel-titanium and the stainless steel archwires, in decreasing order. The frictional force values were directly proportional to the angulation increase between the bracket and the wire.     

陶瓷托槽槽沟形貌及滑动摩擦现象的观察

目的对四种托槽和两种弓丝滑动前后进行外貌和槽沟微观形貌的分析,探讨影响托槽与弓丝间摩擦力大小的因素。方法对四种托槽用立体显微镜对外观形貌及其与两种弓丝滑动前后扫描电镜的微观形貌进行观察,用微硬度测量仪测量四种托槽槽沟、托槽体部位的硬度。结果四种托槽形貌及滑动前后槽沟部位的微观形貌不同,硬度也有差异,硬度由小到大分别为A托槽的金属槽沟部位（F）213．72±57．33HV,D托槽305．76±46．65HV,B托槽1087．12±139．86HV,A托槽体部1111．26±182．52HV,C托槽1309．81±225．56HV。结论硬度和表面粗糙度是影响托槽与弓丝间摩擦力的因素。陶瓷托槽硬度大,表面粗糙,与金属弓丝间的摩擦力大。     

Frictional resistance of self-ligating versus conventional brackets in different bracket-archwire-angle combinations

Objective

To compare the influence of archwire material (NiTi, beta-Ti and stainless steel) and brackets design (self-ligating and conventional) on the frictional force resistance.

Material and Methods

Two types of brackets (self-ligating brackets - Smartclip, 3M/Unitek - and conventional brackets - Gemini, 3M/Unitek) with three (0, 5, and 10 degrees) slot angulation attached with elastomeric ligatures (TP Orthodontics) were tested. All brackets were tested with archwire 0.019"x0.025" nickel-titanium, beta-titanium, and stainless steel (Unitek/3M). The mechanical testing was performed with a universal testing machine eMIC DL 10000 (eMIC Co, Brazil). The wires were pulled from the bracket slots at a cross-head speed of 3 mm/min until 2 mm displacement.

Results

Self-ligating brackets produced significantly lower friction values compared with those of conventional brackets. Frictional force resistance values were directly proportional to the increase in the bracket/ wire angulation. With regard to conventional brackets, stainless steel wires had the lowest friction force values, followed by nickel-titanium and beta-titanium ones. With regard to self-ligating brackets, the nickel-titanium wires had the lowest friction values, significantly lower than those of other materials.

Conclusion

even at different angulations, the self-ligating brackets showed significantly lower friction force values than the conventional brackets. Combined with nickel-titanium wires, the self-ligating brackets exhibit much lower friction, possibly due to the contact between nickel-titanium clips and wires of the same material.     

Debris,Roughness and Friction of Stainless Steel Archwires Following Clinical Use

Objective:To investigate the degree of debris, roughness, and friction of stainless steel orthodontic archwires before and after clinical use.Materials and Methods:For eight individuals, two sets of three brackets (n  =  16) each were bonded from the first molar to the first premolar. A passive segment of 0.019- × 0.025-inch stainless steel archwire was inserted into the brackets and tied by elastomeric ligature. Debris level (via scanning electron microscopy), roughness, and frictional force were evaluated as-received and after 8 weeks of intraoral exposure. Mann-Whitney, Wilcoxon signed-rank, and Spearman correlation tests were used for statistical analysis at the .05 level of significance.Results:There were significant increases in the level of debris (P  =  .0004), roughness of orthodontic wires (P  =  .002), and friction (P  =  .0001) after intraoral exposure. Significant positive correlations (P < .05) were observed between these three variables.Conclusion:Stainless steel rectangular wires, when exposed to the intraoral environment for 8 weeks, showed a significant increase in the degree of debris and surface roughness, causing an increase in friction between the wire and bracket during the mechanics of sliding.     

陶瓷托槽与金属弓丝第二序列成角状态下摩擦性能的研究

目的研究陶瓷托槽与金属弓丝在第二序列成角状态下的摩擦力,探讨影响托槽弓丝间摩擦力的因素。方法进行托槽外观形貌的测量与观察,计算托槽与弓丝第二序列成角下的临界角,并设计带可调节罗盘的载物台,用MTS Tytron250微力试验机体外测试三种陶瓷托槽（A、B、C）和一种金属托槽（D）与0.016英寸不锈钢圆丝（SS）在第二序列成角分别为0度、2度、5度、8度时的最大静摩擦力和滑动摩擦力。结果与0.016英寸SS的摩擦力总体表现出B托槽〉C托槽〉A托槽〉D托槽的趋势,在四种成角状态下的最大静摩擦力随角度加大而增大,总体表现为0度到2度的摩擦力增加没有显著性,增大夹角后摩擦力增加量不同托槽间有差异：A托槽与弓丝在2度到5度成角状态下的摩擦力增加没有显著性,而5度到8度的摩擦力有显著增加;B托槽在2度到5度摩擦力有显著增加,而5度到8度摩擦力增加不显著;虽然2度到5度摩擦力增大没有显著性,但8度与0度状态下相比,C托槽与弓丝间的摩擦力有显著增加;D托槽在2度、5度、8度时摩擦力间差异无显著性。结论选用带金属槽沟的陶瓷托槽,增加陶瓷托槽边缘的圆钝程度等能减缓牙齿移动中托槽-弓丝成角引起的滑动阻力增加;使用传统陶瓷托槽要注意充分排齐。     

Frictional forces between lingual brackets and archwires measured by a friction tester

Frictional resistance tends to rapidly increase as the angle between a bracket and an archwire increases beyond a critical angle. The purpose of this study was to determine a new measuring method with a pin on disk friction tester for the measurement of the frictional force between lingual brackets and archwires. A lingual bracket is different from a labial bracket in dimensions and in some clinical aspects. The influence of artificial saliva was also surveyed. Two brands of lingual brackets and one brand of labial standard bracket with an 0.018-inch slot size were used. Archwires of three alloys (stainless steel [SS], Ormco; beta-Titanium [TM], Ormco; cobalt-chrome, [EL], RMO) with 0.016 x 0.022- and 0.017 x 0.025-inch dimensions were used. Measurements were conducted with an angular velocity of 0.6 degrees/s for 90 seconds and a normal force of 100 g at 25 degrees C in a dry and 34 degrees C in an artificial saliva environment. For SS and EL archwires, the frictional force with the FJT bracket was greater than that with ORM bracket (P < .01). Compared with SS and TM archwires, 0.016 x 0.022-inch EL archwire showed a higher frictional force with two lingual brackets (P < .01). Significant differences in frictional force existed between dry and artificial saliva environments (P < .05), and the effects varied by the bracket-archwire couples. The estimated critical contact angles were greater than the theoretical values. This new method can be a useful protocol for measurement of frictional force because it can measure the frictional force under the conditions of continuous angular change between bracket and archwire.