Resistance To Sliding Research Articles

Friction Mechanics- A Review

Conventional wisdom suggests that resistance to sliding (RS) generated at the wire-bracket interface has a bearing on the force transmitted to the teeth. The relative importance of static and kinetic friction and also the effect of friction on anchorage has been a topic of debate. Lot of research work has been done to evaluate the various factors that affect friction and thus purportedly retards the rate of tooth movement. However, relevancy of these studies is questionable as the methodology used hardly simulates the oral conditions. Lately studies have concluded that more emphasis should be laid on binding and notching of archwires as these are considered to be the primary factors involved in retarding the tooth movement. This article reviews the various components involved in RS and the factors affecting friction. Further, research work should be carried out to provide cost effective alternatives aimed at reducing friction.

Evaluation of the frictional resistance between different bracket types, archwires and ligation materials: An in-vitro study

In orthodontic treatment, brackets need to slide along the archwire to allow for alignment of the teeth. The lesser the friction between the bracket and the archwire, the easier it is to align the teeth and the lighter the forces required to make such movements. In recent years, patients’ esthetic demands have driven the field of orthodontics to find alternatives to conventional stainless steel bracket systems. While ceramic brackets meet the esthetic demands, their inferior frictional characteristics have always been an issue for orthodontists.The present in-vitro research study evaluates and compares the frictional resistance between various types of brackets, archwire materials and ligation methods. The purpose of the study was to equate the frictional resistance among 12 different groups using the universal testing machine, so as to recognize the factors involved in the in-vitro appraisal of resistance to sliding (RS) and inferring their clinical implications. In this study, 120 pre-adjusted edgewise upper central incisor brackets with MBT 0.022″ slot were used, which included 40 standard metal brackets, 40 ceramic brackets, 20 self-ligating metal brackets and 20 self-ligating ceramic brackets. 0.019″ x 0.025″ SS (stainless steel) archwires, esthetic archwires, Teflon-coated ligatures and conventional elastic modules to ligate the archwire to the brackets except in self-ligating brackets, were used. The average frictional resistance of Group A10 was the minimum succeeded by A9, A12, A4, A11, A8, A3, A7, A2, A6, A1 and A5. In the comparison of the mean frictional resistance of 12 different groups, the ANOVA test showed noticeably different frictional resistance amongst the groups (F=745.80, P< 0.001). Self-ligating metal bracket combinations with different archwires showed a significantly smaller magnitude of friction than self-ligating ceramic, metal and ceramic bracket combinations. Teflon-coated ligature combinations possess less friction in comparison with conventional elastomeric module combinations.

Evaluating the Effect of Air Abrasive Polishing on Friction and Surface Micromorphology of Ceramic Brackets Using Different Wires

Objectives: The aim of this in vitro study was to evaluate the Resistance to Sliding (RS) provided by ceramic(Perfect clear) sapphire ceramic brackets using round 2 types of orthodontic wires (Fiber-Reinforced PolymerComposite (FRPC) and Epoxy fully coated Stainless-Steel), before and after the use of sodium bicarbonateairborne particle abrasion, in an experimental model with 3 non levelled brackets and to evaluate the surfacemicromorphology of these brackets by means of scanning electron microscopy.Materials and Methods: 0ne commercial brands of ceramic brackets were evaluated. The fourty specimenswere divided into two groups (n = 20) according to the two type of arch wires and each group was dividedinto four subgroup of five specimens according to the application or not of sodium bicarbonate airborneparticle abrasion for (5, 10 and 20) seconds. A device adapted to a universal testing machine was used tosimulate the movement of retraction in sliding mechanics, measuring the traction force needed to slide 10mm of the wire over the test specimen brackets. The test speed was 5 mm/min. The data were analyzed bytwo-way analysis of variance (ANOVA) and Tukey test.Conclusions: It may be concluded that it is not recommended to apply airborne particle abrasion on the slotsof ceramic.

EFFECTS OF THE INSERTION OF AN ARCHWIRE THIN-WALLED SLEEVE IN ACCELERATING THE CANINE’S TRANSLATION

In sliding mechanics, resistance to sliding (RS), including friction, binding, and notching, generated at a wire-bracket interface has a bearing on the force transmitted to the teeth and further influences the biomechanical behavior associated with tooth movement efficiency. Objective: This study aimed to propose and verify the insertion of a rectangular thin-walled sleeve between an archwire and a bracket to minimize the resistance effect on the biomechanical behavior of tooth movement by using the finite element (FE) method. Material and methods: A 3D FE solid model was constructed and composed of mandibular dentitions, including the surrounding tooth-supporting structures and fixed self-ligating appliances. The translation of the left mandibular canine was simulated (0.1[Formula: see text]mm and 0.3[Formula: see text]mm) from the labial side to the lingual side with or without the thin-walled sleeve by using eight kinds of archwires with various dimensions and cross-sections by FE methods. Results: FE analysis indicated that the canine’s maximum initial displacement and the highest periodontal ligament (PDL) von Mises stress were mainly influenced by the orthodontic wire and the insertion of the thin-walled sleeve. Without the thin-walled sleeve, rectangular archwires could initiate a more optimal tissue response than round archwires. However, the insertion of the thin-walled sleeve between the small round archwire and the bracket significantly presented the most optimal biological responses in all of the cases. Conclusion: FE results revealed that the insertion of a thin-walled sleeve in a small round archwire and a bracket could have a positive influence on final tooth movement.

Effect of different combinations of bracket, archwire and ligature on resistance to sliding and axial rotational control during the first stage of orthodontic treatment: An in-vitro study.

ObjectiveThis study was performed to explore the effect of different bracket, archwire, and ligature combinations on resistance to sliding (RS) and rotational control in first-order angulation.MethodsThree types of brackets (multi-level low friction [MLF], self-ligating, and conventional brackets) coupled with four nickel-titanium archwires (0.012, 0.014, 0.016, and 0.018-inch diameter) and two stainless steel ligatures (0.20 and 0.25 mm) were tested in different first-order angulations (0°, 2°, 4°, 6°, 8°, 10°, 15°, 20°) by using an Instron universal mechanical machine in the dry state at room temperature. RS value was evaluated and compared by one-way ANOVA.ResultsUnder the same angulation, the RS values showed the following order: conventional brackets > MLF brackets > self-ligating brackets. The RS was the highest for conventional brackets and showed a tendency to increase. The RS for MLF brackets coupled with thinner archwires and ligatures showed a similar tendency as the RS for the self-ligating bracket. In contrast, the RS for MLF brackets coupled with thicker archwires and ligatures increased like that for conventional brackets. MLF brackets showed the greatest range of critical contact angles in first-order angulation.ConclusionsThe RS in first-order angulation is influenced by bracket design, archwire, and ligature dimension. In comparison with self-ligating and conventional brackets, MLF brackets could express low friction and rotational control with their greater range of critical contact angles.

Resistance to sliding in orthodontics: misconception or method error? A systematic review and a proposal of a test protocol.

Resistance to sliding (RS) between the bracket, wire, and ligature has been largely debated in orthodontics. Despite the extensive number of published studies, the lack of discussion of the methods used has led to little understanding of this phenomenon. The aim of this study was to discuss variables affecting RS in orthodontics and to suggest an operative protocol. The search included PubMed©, Medline©, and the Cochrane Library©. References of full-text articles were manually analyzed. English-language articles published between January 2007 and January 2017 that performed an in vitro analysis of RS between the bracket, wire, and ligature were included. Study methods were analyzed based on the study design, description of materials, and experimental setup, and a protocol to standardize the testing methods was proposed. From 404 articles identified from the database search and 242 records selected from published references, 101 were eligible for the qualitative analysis, and six for the quantitative synthesis. One or more experimental parameters were incompatible and a meta-analysis was not performed. Major factors regarding the study design, materials, and experimental setup were not clearly described by most studies. The normal force, that is the force perpendicular to the sliding of the wire and one of the most relevant variable in RS, was not considered by most studies. Different variables were introduced, often acting as confounding factors. A protocol was suggested to standardize testing procedures and enhance the understanding of in vitro findings.

In vitro evaluation of the influence of velocity on sliding resistance of stainless steel arch wires in a self-ligating orthodontic bracket.

Of the variables used by in vitro studies of resistance to sliding (RS) in orthodontics, sliding velocity (SV) of the wire is often the one farthest from its clinical counterpart. We investigated whether velocity influences the RS at values approximating the orthodontic movement. A SS self-ligating bracket with a NiTi clip was fixed onto a custom-made model. Different shaped orthodontic SS wires of four sizes and two types (round, 0.020″ and 0.022″; rectangular, 0.016″×0.022″ and 0.017″×0.025″) were tested using an Instron® testing machine. Wires were pulled at four velocities (1×10-2 mm/s, 1×10-3 mm/s, 1×10-4 mm/s, 1×10-5 mm/s). Shapiro-Wilk test was used to evaluate the normal distribution of the data; two-way ANOVA was performed to compare means in the RS with wire characteristics and SV. Significance level was set at P<.05. RS was higher for rectangular wires, and for those with larger diameters. Lower SV was associated with lower RS, with wire type and size having an interaction effect. The RS relatively to SV can be represented as: RS ∝ α[ln(SV)]+β, where α and β are constants. At very low SV and low normal forces, SV influences the RS of SS archwires in orthodontic brackets, and the proportionality is logarithmic. Although respecting these parameters in vitro is challenging, quantitative evaluations of RS should be carried out at clinically relevant velocities if aiming at translational application in the clinical scenario.

Friction in orthodontics.

Conventional wisdom suggests that resistance to sliding (RS) generated at the wire-bracket interface has a bearing on the force transmitted to the teeth. The relative importance of static and kinetic friction and also the effect of friction on anchorage has been a topic of debate. Lot of research work has been done to evaluate the various factors that affect friction and thus purportedly retards the rate of tooth movement. However, relevancy of these studies is questionable as the methodology used hardly simulates the oral conditions. Lately studies have concluded that more emphasis should be laid on binding and notching of archwires as these are considered to be the primary factors involved in retarding the tooth movement. This article reviews the various components involved in RS and the factors affecting friction. Further, research work should be carried out to provide cost effective alternatives aimed at reducing friction.

The effect of perturbations on resistance to sliding in second-order moments comparing two different bracket types.

Orthodontic literature has shown all ligation methods to behave similarly in the clinical situation; however, the reasoning behind this still requires further investigation. A novel frictional device able to measure forces at the level of the bracket along with a custom perturbation device was used to investigate the effect of perturbations on resistance to sliding (RS) using conventional and passive ligated brackets. 150 3M Victory Series twins (0.022 slot) and 150 Damon Q brackets (0.022 slot) were tested using an 0.018 x 0.025 stainless steel wire for RS. There were 5 test groups consisting of equal numbers (n=30) representing combinations of high and low amplitude and frequency of perturbations along with a control. Second order angulation tested ranged from 0 to 6 degrees. Results for conventional brackets in the presence of perturbations at 0 degrees showed there was a statistically significant reduction (P<0.001) in RS when compared to controls. At 6 degrees, this difference (P<0.001) was seen in both high perturbation groups and one of the low perturbation groups. For passive ligated brackets, no statistically significant difference between groups was seen at 0 degrees. However, at 6 degrees high perturbation groups both resulted in statistically significant (P<0.001) reductions in RS when compared to controls. From this study it was concluded that passive ligated brackets have a lower RS when compared to conventional ligated brackets under all test conditions and angulations. Also, amplitude of perturbations has a larger role than frequency in reduction of RS values.

Effect of applied moment on resistance to sliding among esthetic self-ligating brackets

To determine the effect of mode of ligation and bracket material on resistance to sliding (RS) by comparing various esthetic brackets of conventionally ligated and self-ligating (SL) designs under an increasing applied moment in the second-order dimension. Eight different commercially available esthetic brackets of SL and conventional elastomeric-ligated (CL) designs were mounted on a testing apparatus to simulate canine retraction using sliding mechanics and the application of a moment on 0.019″×0.025″ stainless steel archwire. The samples examined were the CL brackets Clarity™, Inspire Ice™, SpiritMB™, and Mystique™, and the SL brackets ClaritySL™, In-OvationC™, In-OvationR™, and Smartclip™. The RS at calculated moments of 2000 g-mm and 4000 g-mm was determined and compared between the various brackets. Descriptive measures and one-way analysis of variance were used to calculate means and statistical differences among the bracket types. The CL monocrystalline bracket displayed significantly greater (P < .05) RS than all other brackets tested. Among the other brackets, the range of RS values was 145.8-191.7 g and 291.9-389.2 g at moments of 2000 g-mm and 4000 g-mm, respectfully, though these differences were not significant (P < .05). All brackets tested displayed greater levels of RS (P < .05) at 4000 g-mm than at 2000 g-mm. With the exception of the CL monocrystalline bracket, all brackets displayed comparable amounts of RS regardless of mode of ligation or bracket slot material.

Effects of bracket design on critical contact angle

To explore how the position of the bracket slots relative to the archwire influences the friction between them, and how bracket design affects the critical contact angle (θc). Two kinds of stainless steel archwires (0.016 and 0.019 × 0.025-inch) were tested against four kinds of brackets (Transmission Straight Archwire bracket, Domestic MBT bracket, Tip-Edge Plus bracket, and BioQuick self-ligation bracket) in the dry state. Resistance to sliding (RS) was measured as an increase in contact angle (θ). The value of θc was calculated by two linear regression lines. Friction remained stable when θ < θc, then increased linearly when θ > θc. The θc values of the Tip-Edge Plus bracket and Transmission Straight Archwire bracket were significantly larger than those for the Domestic MBT bracket and BioQuick self-ligation bracket. The relationship between the archwire and bracket slot significantly affects the resistance to sliding. The "edge-off" structure of the Tip-Edge Plus bracket and Transmission Straight Archwire bracket could help to increase the θc value, and to expand the passive configuration range.

Effect of sodium bicarbonate air abrasive polishing on resistance to sliding during tooth alignment and leveling: An in vitro study

Abstract Objective: The aim of this in vitro study was to evaluate the Resistance to Sliding (RS) provided by metallic brackets and 3 types of orthodontic wires (TMA, SS and NiTi), before and after the use of sodium bicarbonate airborne particle abrasion, in an experimental model with 3 non leveled brackets. Materials and Methods: The bicarbonate airborne abrasion was applied perpendicularly to the bracket slots at a distance of 2 mm, for 5 seconds (T2) and 10 seconds (T3) on each bracket slot. In a universal testing machine, the wires were pulled through a set of 3 non leveled brackets at a cross head speed of 50 mm/min for a distance of 10 mm, and static and kinetic friction readings were registered at T1 (no airborne abrasion), T2 and T3. Results: For all tested wires, a significant RS increase between T1 and T3 (P&lt;0.001) was seen. For SS and TMA wires, there was a statistically significant RS increase between T1 and T2 (P&lt;0.001). Between T2 and T3, RS increase was significant for TMA (P&lt;0.001) and NiTiwires (P&lt;0.05). Conclusions: Sodium bicarbonate air abrasive polishing during orthodontic treatment is not recommended, once this procedure promoted a significant RS increase between the metallic brackets and all the three types of wires tested.

In vitroevaluation of resistance to sliding in self-ligating and conventional bracket systems during dental alignment

ObjectiveTo investigate the resistance to sliding (RS) in self-ligating and conventional ligation bracket systems at 5 different second-order bracket angulations by using low-stiffness alignment wires in a 3-bracket experimental model and to verify the performance of the main RS components in both systems when these wires are used.MethodsInteractive self-ligating brackets with closed and open slides were used for the self-ligating (SL) and conventional ligation (CL) groups, respectively; elastomeric ligatures (1 mm inner diameter) were used in the latter system. The alignment wire used was 0.014 inch heat-activated NiTi (austenitic finish temperature set at 36℃ by the manufacturer). A custom-made testing machine was used to measure frictional resistance. Tests were repeated 5 times at every angulation simulated. All data were analyzed statistically.ResultsThe RS increased significantly with increasing angulation in both SL and CL groups (p < 0.0001). However, the RS values were significantly higher at every angulation (p < 0.0001) in the CL group.ConclusionsDespite the relevance of the binding phenomenon, ligation forces predominantly affect the RS when low-stiffness alignment wires are used.

A comparison of resistance to sliding of self-ligating brackets under an increasing applied moment

To test the null hypotheses that at clinically relevant amounts of applied moment, there are no differences in the amount of resistance to sliding (RS) between self-ligating (SL) and conventionally ligated (CL) brackets on both stainless steel (SS) and nickel-titanium (NT) archwire. Three different SL brackets and one CL bracket, all 0.022″ slot, were tested on a custom-built device to simulate canine retraction mechanics in the second-order dimension. The setup allowed for simultaneous and continuous measurement of RS and applied moment at the bracket-archwire interface. The brackets tested were Damon3, In-Ovation R, Smartclip, and Victory, all of which were tested with 0.019″ × 0.025″ SS and NT archwires. The RS at calculated moments of 2000 g-mm and 4000 g-mm was determined and compared between the various brackets and both archwire types. Descriptive measures, analysis of variance, and Tukey-Kramer post-test comparisons were used to calculate results. All brackets displayed a greater amount of RS with NT than with SS archwires. At the higher moment levels (4000 g-mm), no significant reduction in RS was found between CL and SL brackets on both SS and NT archwires. At lower levels of applied moment (2000 g-mm), reductions in RS of 18% (42.7 g) and 18% (38.5 g) were found between the CL bracket and the best performing SL bracket on NT and SS, respectively. At low values of applied moment, some statistical differences were found; however, in general, the differences in RS amongst the various SL and CL brackets tested may not be clinically relevant.

The effect of Teflon coating on the resistance to sliding of orthodontic archwires

Teflon is an anti-adherent and aesthetic material. The aim of this study was to evaluate, in vitro, the influence of Teflon coating on the resistance to sliding (RS) of orthodontic archwires. For this purpose, Teflon-coated archwires were examined using frictional resistance tests by means of a universal testing machine and compared with conventional uncoated wires. Twelve types of archwires with round and rectangular sections (0.014, 0.018, and 0.018 × 0.025 inches) and of different materials (stainless steel and nickel-titanium) were tested with two passive self-ligating brackets (SmartClip™ and Opal(®)) and one active self-ligating bracket (Quick(®)). Each archwire-bracket combination was tested 10 times under 8 simulated clinical scenarios. Statistical comparisons were conducted between the uncoated and Teflon-coated archwires using Wilcoxon and Mann-Whitney tests, and linear regression analysis. For all bracket-archwire combinations, Teflon-coated archwires resulted lower friction than the corresponding uncoated archwires (P < 0.01). The results showed that Teflon coating has the potential to reduce RS of orthodontic archwires.

Active and passive self-ligation—a myth?

To compare the frictional behavior of several self-ligating brackets with that of normal brackets both with and without tipping force-moments and in combination with different archwire dimensions. The resistance to sliding (RS) of seven self-ligating brackets, a conventional bracket, and a ceramic bracket with a low-friction clip were evaluated in combination with three different archwires and tipping force-moments of 0 and 10 Nmm. The center of rotation for the measurements was set within the center of the bracket or with a 10-mm offset. Resistance to sliding was measured using an Instron 3344 at a cross-head speed of 10 mm/min at a temperature of 36°C. Without a tipping moment, RS increased with the active self-ligating brackets with increasing archwire size. No RS was found for any of the passive self-ligating brackets. The 10-Nmm tipping moment resulted in more RS and was similar for all bracket and archwire combinations. RS was approximately doubled when the center of rotation was located at the bracket rather than with a 10-mm offset. RS between brackets and archwires is highly dependent on the experimental setup. Different setups can result in contradictory results. Almost 1 N of traction force is lost in RS when a moment of 10 Nmm is placed at a rotational center 10 mm from the bracket.

The effect of different combinations of tip and torque on archwire/bracket friction

The aim of this laboratory-based study was to investigate the effects of different combinations of tip and torque upon friction between an orthodontic bracket and archwire using a specially made jig. Victory Twin Series upper premolar brackets (3M Unitek) were mounted on a jig, which allowed tip and torque values in the slot to be varied without altering the centre of rotation. The jig was mounted on an Instron machine and resistance to sliding (RS) was measured as brackets were drawn along rectangular 0.019 x 0.025 inch wires at various combinations of tip and torque from 0 to 12 degrees. Five tests were carried out for each combination. The results were analysed using analysis of variance and Tukey's pairwise comparisons by means of the Minitab statistical package. Increasing tip and torque produced increases in sliding resistance from 1.35 to 19.08 N. Both tip and torque had significant effects on friction. RS was significantly increased by tip and torque separately (P < 0.001) and in combination (P < 0.001), although tip was the more powerful influence.

Influence of interbracket distances on the resistance to sliding of orthodontic appliances

The influence of interbracket distance (IBD) on the resistance to sliding (RS) was evaluated. Commercially pure titanium brackets (CP-Ti; 0.018- and 0.022-in slots, width = 0.14-in) were tested against 0.016 x 0.022-in rectangular stainless steel (SS), nickel titanium (Ni-Ti), and beta-titanium (beta-Ti) archwires in the dry and wet (human saliva) states. With a custom testing apparatus that simulated a 3-bracket system, the RS was measured at a normal force of 300 cN and at second-order angles (theta) ranging from -9 degrees to +9 degrees. Twenty-three pairs of IBDs (written as IBD1_IBD2) were varied to simulate clinically relevant biomechanical scenarios with IBD ranging from 16 to 7 mm. In the dry state, the kinetic frictional coefficients (micro(k)) were equal to 0.12, 0.23, and 0.24 for the SS, Ni-Ti, and beta-Ti archwires against the CP-Ti brackets, respectively. The presence of saliva slightly increased micro(k). The RS was inversely proportional to the total IBD (IBD(T) = IBD1 + IBD2) regardless of archwire alloy or bracket slot. Elastic binding (BI = RS - frictional force in the passive region) did not depend on the order of the IBDs in the IBD1_IBD2 pair. For a specific archwire-bracket couple, the BI of an IBD1_IBD2 pair is equal to any other pair with an equal IBD(T). Although no significant difference was found between the coefficients of binding (micro(BI)) for SS and beta-Ti archwires, the micro(BI)'s of Ni-Ti archwires were lower and significantly different. The micro(BI) was linearly related (P<.01) to IBD(T) and total archwire beam length (L(T)).

Resistance to sliding of titanium brackets tested against stainless steel and beta-titanium archwires with second-order angulation in the dry and wet states

With the increased awareness of Ni allergies, alternative alloys for orthodontic products must be identified. The properties of these new products must be determined. Rectangular (0.017 x 0.025 in) stainless steel (SS) and beta-titanium (beta-Ti) archwires were tested against commercially pure titanium brackets (CP-Ti, 0.018-in slot) in the dry state and with whole human saliva. Resistance to sliding (RS) was measured as a function of 5 normal forces (N, 200 to 950 cN), 32 angles (theta, -12 degrees to +12 degrees), and 1 interbracket distance (IBD, 18 mm). With clearance between the archwire and the bracket (passive region, theta < or =theta(c)), the frictional coefficients (mu) of the SS archwire and the CP-Ti bracket couples were 0.12 and 0.13 for the dry and wet tests, respectively; for the beta-Ti archwire and the CP-Ti bracket couples, the mu values were 0.29 and 0.28 for the dry and wet tests, respectively. For an theta without clearance (active region, theta > or =theta(c)), RS increased as a function of theta and N. To examine the rates of binding (mu(BI)) in this active region, the value of classical friction (mean of the passive region data) was subtracted from RS to yield BI, and the value of theta(c) was subtracted from each theta to yield relative contact angles (theta(r)). Because of the unique relationship between the frictional and mechanical properties of these SS and beta-Ti archwires tested against the CP-Ti brackets at a large IBD, the mu(BI) values for these archwire-bracket couples were nominally equivalent (24 to 30 cN per degree). Clinical outcomes would be unaffected by this 6 cN per degree (approximately 0.2 oz-force per degree) difference. When all kinetic data in the elastic region (theta(r) < or =5 degrees ) were combined, mu(BI) equaled 28 cN per degree. Above this region (theta(r) > or =5 degrees ), the data for the SS archwire and CP-Ti bracket couples were less scattered than those for the beta-Ti archwire and the CP-Ti bracket couples. This demarcation from linearity was designated as theta(z) and indicated the end of the elastic region and the beginning of the plastic region, above which sliding can eventually cease. This region (theta > or =theta(z)), the binding region (theta(c) < or =theta < or =theta(z)), and the classical friction region (theta < or =theta(c)) were described in a model. This model explains, in part, the equivalent values of mu(BI) for SS and beta-Ti archwires tested against CP-Ti brackets.

Effects of ligation type and method on the resistance to sliding of novel orthodontic brackets with second-order angulation in the dry and wet states.

Rectangular stainless steel (SS) archwires were coupled with four SS bracket designs: Mini Diamond Twin, which was a conventional twin bracket; VersaT, which had bumps along the slot floor and rounded slot walls; Shoulder, which had bosses outside the tie-wings to lift the ligation off the archwire; and Synergy, which had bosses between the outer and inner tie-wings, bumps along the slot floor, and rounded slot walls. For all designs, the values of resistance to sliding (RS) were measured at five normal forces and 32 second-order angulations in the dry and wet (saliva) states. RS values at these same angles and states were also measured for the following: Mini Diamond Twin brackets ligated with rings and SS ligature wires; VersaT brackets ligated with rings; Shoulder brackets ligated with rings in a figure-8 and a figure-O around the tie-wings; and Synergy brackets ligated with rings around the outer tie-wings and around the inner tie-wings. In both states, the coefficients of friction were similar for the Mini Diamond Twin, VersaT, and Synergy brackets; the values for the Shoulder brackets were slightly greater than for the other three designs. In the passive configuration, the features of the Shoulder and Synergy brackets reduced RS when the rings were not in contact with the archwires. In the active configuration, the binding behavioral patterns of the brackets were not influenced by ligation methods. Thus, these different ligation types and methods only affected the classical frictional component of RS in the passive configuration.