Forces in the presence of ceramic versus stainless steel brackets with unconventional vs conventional ligatures

OBJECTIVE: To compare the forces resulting from four types of bracket/ligature combinations: ceramic brackets and stainless steel brackets combined with unconventional elastomeric ligatures (UEL) and conventional elastomeric ligatures (CEL) during the leveling and aligning phases of orthodontic therapy. MATERIALS AND METHODS: The testing model consisted of five 0.022-inch preadjusted brackets (second premolar, first premolar, canine, lateral incisor, and central incisor) for each of the two bracket types. The canine bracket was welded to a sliding bar that allowed for different amounts of offset in the gingival direction. The forces generated by a 0.014-inch superelastic nickel titanium wire in the presence of either the UEL or CEL bracket/ligature systems at different amounts of upward canine misalignment (1.5 mm, 3 mm, 4.5 mm, and 6 mm) were recorded. RESULTS: Significant differences were found between UEL and CEL systems for all tested variables (P < .01) with the exception of the canine misalignment of 1.5 mm. The average amount of recorded force in the presence of CEL was negligible with 3.0 mm or greater of canine misalignment. On the contrary, during alignment, a force available for tooth movement was recorded in the presence of both ceramic and stainless steel brackets when associated with UEL. CONCLUSIONS: The type of ligature used influenced the actual amount of force released by the orthodontic system significantly more than the type of bracket used (stainless steel vs ceramic).     

Friction produced by types of elastomeric ligatures in treatment mechanics with the preadjusted appliance

The objective was to compare the frictional forces generated by new nonconventional passive elastomeric ligatures (NCL) and conventional elastomeric ligatures (CL) under dry conditions. An experimental model reproducing the right buccal segment of the upper arch and consisting of five stainless steel 0.022-inch preadjusted brackets (from the second premolar through the central incisor) was used to assess both static and kinetic frictional forces produced by NCL and CL. The frictional forces generated by the 0.019 x 0.025-inch stainless steel wire with the two types of elastomeric ligatures were recorded by sliding the wire into the aligned brackets. The friction produced by the 0.014-inch superelastic nickel titanium wire was evaluated both in the presence of aligned brackets and of three-mm misaligned canine bracket. The amount of both static and kinetic frictions were minimal (<10 g) in the NCL group in the presence of aligned brackets with both types of wires, whereas it ranged from a minimum of 95.6 g for the 0.014-inch superelastic nickel titanium wire to a maximum of 590.7 g for the 0.019 x 0.025-inch stainless steel wire when using CL. The amount of both static and kinetic frictions in the presence of a misaligned canine bracket in the NCL group were less than half of that shown by the CL group. A recently developed passive ligature system is able to produce significantly lower levels of frictional forces in vitro when compared with conventional elastomeric modules.     

The SmartClip Self-Ligating Appliance System

Use of elastomeric ligatures and/or tightened stainless steel ligatures with the conventional twin-wing preadjusted appliance systems often produce excessive contact forces between the orthodontic archwire and the bracket slot thus increasing the resistance to sliding. This is a disadvantage in certain situations in the beginning of the orthodontic treatment where resistance to sliding will often prevent the desired movement of teeth and may cause undesirable tooth movement. The SmartClip self-ligating bracket system provides a novel passive self ligation system with the advantages of a passive system but with the built-in finishing capacity of the traditional twin wing preadjusted system. Clinical observations and experience have found that the easier and more definitive wire engagement may positively impact the speed of the alignment and leveling. The wire engagement is quicker compared with complete ligation with elastomeric modules or stainless steel ties reducing the active chair side time. During the later stages of treatment the reduced resistance to sliding may facilitate faster space closure with less demand on anchorage and consequently less undesirable tooth movement and a reduction of overall treatment time. The use of braided rectangular wires in the finishing stage has been found advantageous for maintaining torque control while correcting minor vertical discrepancies. In the conventional preadjusted technique the authors were refitting round Nitinol wire for the finishing stage whereas with the passive self-ligation system they would risk losing some of the achieved alignment as the smaller round wires do not fill the slot sufficiently. The braided wires maintain the slot fill while allowing vertical changes if needed. An alternative is, of course, to push the archwire to the base of the bracket slot with an elastomeric module or a steel ligature tie.     

Evaluation of methods of archwire ligation on frictional resistance

The aim of the study was to investigate the effect of elastomeric type and stainless steel (SS) ligation on frictional resistance using a validated method. To assess the validity of the new test system to measure mean frictional forces, SS and TMA wires, each with dimensions of 0.017 x 0.025 and 0.019 x 0.025 inches, were used in combination with a self-ligating Damon II bracket or a conventional preadjusted edgewise premolar SS bracket without ligation. Four types of elastomeric module, purple, grey, Alastik or SuperSlick, and a pre-formed 0.09 inch SS ligature were then assessed as methods of ligation using preadjusted edgewise premolar SS brackets. The specimens were tested on a Nene M3000 testing machine, with a crosshead speed of 5 mm/minute and each test run lasted for 4 minutes. Each bracket/wire combination with each method of ligation was tested 10 times in the presence of human saliva and the mean frictional force was recorded. The mean frictional forces were compared using three-way analysis of variance. The Damon II self-ligating bracket and unligated conventional SS bracket produced negligible mean frictional forces with any of the wires tested. For the 0.017 x 0.025 SS, 0.019 x 0.025 SS or 0.019 x 0.025 inch TMA wires, SS ligatures produced the lowest mean frictional forces. With the 0.017 x 0.025 TMA wire, purple modules produced the lowest mean frictional force. There was no consistent pattern in the mean frictional forces across the various combinations of wire type, size and ligation method. Under the conditions of this experiment, the use of passive self-ligating brackets is the only method of almost eliminating friction.     

Resistance to sliding with 3 types of elastomeric modules

INTRODUCTION: Super Slick (TP Orthodontics, LaPorte, Ind), a polymeric-coated ligature, has recently been introduced to the orthodontic market. The manufacturer claims it will significantly reduce friction. The purposes of this study were to determine whether Super Slick modules show lower friction than round and rectangular modules and to put the frictional forces into perspective with a self-ligating bracket. METHODS: Maxillary premolar, stainless steel, self-ligating, and monocrystalline brackets with .022-in slots were used with straight lengths of .018-in and .019 x .025-in stainless steel wires. Buccal segment models were set up with 1 molar band and 2 premolar brackets for each test group: self-ligating brackets with the slide closed, self-ligating brackets with the slide open, and monocrystalline brackets. The latter 2 groups were tested with all 3 types of elastomeric module. Each setup was tested both under dry conditions and after soaking in a water bath for 1 hour. RESULTS: The self-ligating brackets demonstrated virtually zero friction with each combination of wire and environmental condition. When the different bracket and elastomeric module combinations were compared, significant differences were observed. In all but 2 combinations, round modules provided the least resistance to sliding and rectangular modules the greatest, with Super Slick modules in between the 2. The self-ligating bracket provided the least resistance to sliding of all the bracket/ligation combinations and almost entirely eliminated friction under the conditions of this experiment. CONCLUSIONS: Super Slick modules demonstrated greater resistance to sliding than conventional round modules, but not rectangular. Self-ligating brackets provided the least resistance to sliding of all bracket/ligation combinations and were the only method that almost entirely eliminated friction. The .018-in and .019 x .025-in wires exhibited similar friction in the dry state, but, when wet, the .018-in wire produced less friction. Ceramic brackets demonstrated greater resistance to sliding than stainless steel brackets. Lubrication reduced the friction with .018-in wires and increased it for .019 x .025-in wires.     

两种不同弹力结扎对滑动摩擦力大小影响的体外实验研究

目的通过体外实验研究MBT金属托槽应用两种不同的弹力结扎时滑动摩擦力的大小。方法选择3M公司的上颌第二双尖牙MBTmini金属托槽和0．46×0．64mm（0．018×0．025英寸）不锈钢弓丝,分别采用意大利Leone公司生产的Slide^TM结扎圈和美国TP公司生产的传统弹力圈结扎,应用自行设计开发的摩擦力测试仪,弓丝沿托槽低速滑动,并在滑动中保持特定的托槽——弓丝成角,共计12个角度。测量每一种弓丝、不同角度下的滑动摩擦力大小。结果在被动状态下两种结扎方式的滑动摩擦力均基本保持不变,Slide^TM结扎的摩擦力非常小,几乎可以忽略不计;在主动状态下,摩擦力随角度增加而增大,slide^TM结扎产生的滑动摩擦力仍明显小于传统弹力结扎。结论应用LeoneSlide^TM结扎圈,可以显著减小矫治器的滑动摩擦力。     

Frictional resistance of orthodontic wires tied with 3 types of elastomeric ligatures

The aims of this study were to determine and compare frictional resistance obtained by low-friction and conventional elastomeric ligatures in the presence of artificial saliva, and observe whether this variable changed after 21 days. Super Slick? low-friction elastomeric ligatures and conventional ligatures of the brands TP conventional? and Unitek? were placed on standard edgewise maxillary central incisor metal brackets, slot .022" × .028" tying rectangular orthodontic wires .018" × .025". Three experimental groups were arranged according to the type of ligature and a control group in which no wires were used. The friction values obtained between the bracket/wire/ligature set were measured using a Universal Test Machine at a speed of 20 mm/minute, at two experimental time intervals: T0 - immediately after specimen fabrication; and T1 - 21 days after fabrication and immersion in artificial saliva at 37 oC. Conventional Unitek ligatures and the low-friction ligature (Super Slick) showed the lowest friction values at T0. After 21 days (T1), however, conventional Unitek ligatures presented the lowest value. All groups assessed from T0 to T1 showed a numerical reduction in friction values, suggesting that time, heat and humidity may cause elastic degradation, however this was not verified statistically (P > 0.05).     

Physical and chemical properties of orthodontic brackets after 12 and 24 months: in situ study

Objective

The aim of this article was to assess how intraoral biodegradation influenced the surface characteristics and friction levels of metallic brackets used during 12 and 24 months of orthodontic treatment and also to compare the static friction generated in these brackets with four different methods of the ligation of orthodontic wires.

Material and Methods

Seventy premolar brackets as received from the manufacturer and 224 brackets that were used in previous orthodontic treatments were evaluated in this experiment. The surface morphology and the composition of the deposits found in the brackets were evaluated with rugosimetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Friction was analyzed by applying tensile tests simulating sliding mechanics with a 0.019x0.025" steel wire. The static friction levels produced by the following ligation methods were evaluated: loosely attached steel ligature around all four bracket wings, steel ligature attached to only two wings, conventional elastomeric ligation around all 4 bracket wings, and non-conventional Slide^® elastomeric ligature.

Results

The results demonstrated the presence of biodegradation effects such as corrosion pits, plastic deformation, cracks, and material deposits. The main chemical elements found on these deposits were Carbon and Oxygen. The maximum friction produced by each ligation method changed according to the time of intraoral use. The steel ligature loosely attached to all four bracket wings produced the lowest friction levels in the new brackets. The conventional elastic ligatures generated the highest friction levels. The metallic brackets underwent significant degradation during orthodontic treatment, showing an increase in surface roughness and the deposit of chemical elements on the surface.

Conclusion

The levels of static friction decreased with use. The non-conventional elastic ligatures were the best alternative to reduce friction.     

Archwire seating forces produced by different ligation methods and their effect on frictional resistance

The aims of this study were to determine the mean tensile force of four different elastomeric modules, the archwire seating force of different ligation methods, and its effect on frictional resistance.To determine the mean tensile force, each elastomeric module (purple, grey, Alastik, and SuperSlick) was extended by 5 mm using two hooks attached to a load cell using a Nene M3000 testing machine. To assess the median archwire seating force, a maxillary premolar bracket (3M Unitek) was welded to a sheet of stainless steel (SS) and glued to a Perspex block. The bracket base was removed and the cut continued into the Perspex below. A length of test wire was taken and bent to form a "U" shape, with the middle portion 20 mm in length. The free ends of the wire were secured to the load cell of the Nene testing machine. Two wire sizes were tested, 0.017 x 0.025 and 0.019 x 0.025 inch SS. The load cell was activated and the force with which the wire was displaced into the slot by the ligation method was measured. Four types of elastomeric module were tested together with a pre-formed 0.09 inch SS ligature. The experimental method used to determine the mean frictional force of each module and wire size was carried out using a method described previously.Statistically significant differences existed in the mean tensile forces and median archwire seating forces between the elastomeric modules. Grey modules with either size wire produced the lowest median archwire seating force, whereas SS ligatures produced the highest forces. SS ligatures with either wire produced the lowest mean frictional forces, whereas grey modules produced significantly higher mean frictional force (P < 0.01). The force with which the wire was seated into the bracket did not seem to be related to the subsequent amount of mean frictional force produced.     

The influence of the SPEED bracket's self-ligating design on force levels in tooth movement: a comparative in vitro study

In the SPEED bracket system the arch wire is retained in the arch wire slot by means of a built-in, escape-proof, flexible spring clip. Unlike the traditional edgewise bracket, it requires no ligature tie, thus ostensibly reducing the frictional force generated by the more-established elastomeric or steel-tie ligature systems. An in vitro study was designed to compare the level of force required to move four distinct arch wires a similar distance, on six occasions, through four ligated bracket systems and the self-ligated SPEED bracket. The results consistently demonstrated a significant decrease in the force level required for the SPEED bracket with all four arch wires when compared with elastomeric and steel-tie ligation in both metal and plastic bracket systems.     

国产3B自锁托槽、3B直丝弓托槽和Damon Q自锁托槽椅旁操作时间的对比研究

目的比较国产3B自锁托槽、Damon Q自锁托槽以及国产3B直丝弓托槽的椅旁操作时间,为国产3B自锁托槽的临床应用提供参考依据。方法选择正畸患者80例,其中20人使用国产3B自锁托槽(3B自锁组),20人使用Damon Q自锁托槽(Damon Q自锁组),20人使用国产3B直丝弓托槽+结扎丝结扎(结扎丝组),20人使用国产3B直丝弓托槽+橡皮圈结扎(橡皮圈组)。待患者上下颌牙列基本排齐后,使用0.018*0.025英寸镍钛方丝入槽,记录全口结扎和拆除时间。采用单因素方差分析,比较4组患者的结扎和拆除时间。结果 3B自锁组的结扎、拆除和总时间均明显短于结扎丝组和橡皮圈组(P<0.01)。3B自锁组和Damon Q自锁组在结扎、拆除和总时间方面的差异均无统计学意义(P>0.05)。结论无论是采用结扎丝结扎还是橡皮圈结扎,国产3B自锁托槽的椅旁操作时间明显短于直丝弓托槽,且与进口的Damon Q自锁托槽相比无明显统计学差异。     

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??Objective    To observe the change of the surface structure of the arch wire due to different orthodontic bracket designs and ligations. Methods    In the dry environment the sliding of bracket  on the arch wire was simulated??and WDW20 & 0.5 electronic universal testing machine was used to provide uniform traction??the arch wire was scanned with SEM. Results    The wires investigated in this study had varying degrees of change??the MLF bracket with 0.2 mm ligation group had minimal changes to the arch wire surface. The scratches of arch wire surface distributed evenly on elastic ligation ring group??0.25 mm ligature wire was likely to cause the uneven distribution of stress. Conclusion    The different ways of ligation have different effects on morphological structure of the surface of the arch wire. The coarser ligature wires have bigger influence on the arch wire surface structure. Different orthodontic bracket designs will change the arch wire surface structure.     

Friction of orthodontic elastomeric ligatures with different dimensions

The aim of this study was to evaluate in vitro the effect of variations in the size of elastomeric ligatures on the static frictional resistance generated by orthodontic sliding mechanics under dry condition. Frictional forces generated by elastomeric ligatures treated with a lubricating material (silicone) were analyzed as well. An Instron testing machine was used to assess the static frictional forces of a 0.019 x 0.025-inch stainless steel rectangular wire that was ligated to a molar convertible tube and to three stainless steel 0.022-inch pre-adjusted brackets with elastomeric ligatures with different dimensions: small, medium, and large. The static friction produced by two prototypes of silicone-lubricated elastomeric ligatures was also measured. The small and medium elastomeric ligatures produced significantly less friction than the large ligatures. No statistically significant difference was found between small and medium ligatures. The decrease in frictional forces of small and medium modules had to be ascribed mainly to the smaller thickness of both ligatures with respect to large ligatures. The lubricated elastomeric ligatures generated significantly smaller frictional forces than nonlubricated elastomeric ligatures with different dimensions. The variation in the dimensions of the elastomeric ligatures is able to influence the static frictional resistance generated by orthodontic sliding mechanics in the buccal segments. The use of small and medium elastomeric ligatures determines a 13-17% decrease in static friction compared with large ligatures. Silicone-lubricated modules can reduce static friction by 23-34% with respect to the small and medium nonlubricated elastomeric ligatures and by 36-43% compared with nonlubricated large ligatures.     

Evaluation of friction during sliding tooth movement in various bracket-arch wire combinations.

Frictional forces during simulated sliding tooth movement were measured with a model that was representative of the clinical condition. The model allowed tipping of the tooth until contact was established between the arch wire and diagonally opposite corners of the bracket wings; it also allowed rotation until the wire contacted opposite corners of the ligature tie, or the buccal shield with self-ligating brackets, and the base of the slot. Conventional and self-ligating stainless steel brackets as well as conventional ceramic brackets, and ceramic brackets with a stainless steel slot, all with 0.022 inch bracket slot, were tested with 0.019 x 0.025 inch arch wires of stainless steel, nickel titanium, and beta titanium. Each of the 12 bracket-arch wire combinations was tested 10 times. No significant interaction was detected between brackets and arch wires (P = .89), but the bracket and arch wire effects were significant (P < .001). The pairwise differences between conventional and self-ligating stainless steel brackets and ceramic brackets with stainless steel slot were not significant. However, the conventional ceramic brackets generated significantly higher friction than the other brackets tested. Beta titanium arch wires produced higher frictional forces than nickel titanium arch wires, but no significant differences were found between each of the two and stainless steel arch wires. Attempts to identify differences in surface scratches of the arch wires produced by the different brackets were unsuccessful.     

First order couples induced by nickel–titanium archwires featuring an electrochemically refined surface during simulated rotation of teeth

Objective

The significance of friction inside the bracket–wire–ligature interface remains controversial despite having been investigated for four decades. Numerous approaches have been proposed to reduce friction via any of the elements of the interface, key among them being recently developed bracket modifications and the introduction of surface-modified wires. The present study explored whether archwires treated by a novel electrochemical process of surface refinement influence first-order couples generated inside self-ligating and conventionally ligated brackets during tooth rotation.

Materials and methods

A surface-refined nickel–titanium archwire (OptoTherm/LoFrix?) was compared ex vivo to a non-refined archwire of the same production lot (OptoTherm?), the nominal dimensions being 0.014×0.025’’ in both cases. Three bracket designs were included to assess the role of the ligation mechanism: (1) Carrière SLB? passive self-ligating brackets, (2) BioQuick® active self-ligating brackets, and (3) Classic Series® conventionally ligated brackets. The brackets were bonded to leveled tooth elements on a resin mandibular arch. To simulate rotation, the lower left first premolar was removed and connected to a biomechanical measuring system. The simulation procedures were performed at 37°C.

Results

The various bracket designs yielded characteristic torque curves mainly reflecting the play of the archwire specimens inside their slots. While the passive self-ligating brackets exhibited 2?3° of play in either direction, both the active self-ligating brackets and the conventional brackets with elastic ligatures did not reveal any play. Torque levels ranged from 8 Nmm inside the conventional brackets to 13 Nmm inside the passive self-ligating brackets. The surface-refined archwires induced significantly (up to 35%) lower torque levels and were slightly reduced in cross-section.

Conclusion

Electrochemical surface refinement can significantly reduce first order couples induced by archwires. This effect is caused by less friction, but also by the slightly reduced cross-section of these wires.     

Sliding mechanics of coated composite wires and the development of an engineering model for binding

A tribological (friction and wear) study, which was designed to simulate clinical sliding mechanics, was conducted as part of an effort to determine the suitability of poly(chloro-p-xylylene) coatings for composite orthodontic archwires. Prototype composite wires, having stiffnesses similar to those of current initial and intermediate alignment wires, were tested against stainless steel and ceramic brackets in the passive and active configurations (with and without angulation). Kinetic coefficient of friction values, which were determined to quantify sliding resistances as functions of the normal forces of ligation, had a mean that was 72% greater than uncoated wire couples at 0.43. To improve analysis of the active configuration, a mathematical model was developed that related bracket angulation, bracket width, interbracket distance, wire geometry, and wire elastic modulus to sliding resistance. From this model, kinetic coefficients of binding were determined to quantify sliding resistances as functions of the normal forces of binding. The mean binding coefficient was the same as that of uncoated wire couples at 0.42. Although penetrations through the coating were observed on many specimens, the glass-fiber reinforcement within the composite wires was undamaged for all conditions tested. This finding implies that the risk of glass fiber release during clinical use would be eliminated by the coating. In addition, the frictional and binding coefficients were still within the limits outlined by conventional orthodontic wire-bracket couples. Consequently, the coatings were regarded as an improvement to the clinical acceptability of composite orthodontic archwires.     

低摩擦结扎圈在牙齿排齐阶段静摩擦力的实验研究

目的研究低摩擦结扎圈Slide、Neo-Clip和普通结扎丝／圈在牙齿排齐阶段静摩擦力的差异，并与自锁托槽DamonMx和Smartclip比较。材料和方法选取临床牙列拥挤患者的上颌模型制作Typodont，采用MBT普通金属托槽、0．014NT弓丝，在万能测试机上测量不同结扎方式时矫治器系统的静摩擦力。结果Slide结扎时，矫治器系统的静摩擦力与自锁托槽DamonMx和Smartclip之间的差异无显著性，且显著低于Neo-Clip结扎和传统结扎丝／圈结扎。Neo-Clip结扎时矫治器系统静摩擦与Smartclip、普通结扎丝结扎差异无显著性，且显著低于普通结扎圈结扎。结论低摩擦结扎圈在牙齿排齐阶段，可以使矫治器系统静摩擦力降低至自锁托槽水平。     

Evaluation of friction between edgewise stainless steel brackets and orthodontic wires of four alloys

This investigation was designed to determine the effects of wire size and alloy on frictional force generated between bracket and wire during in vitro translatory displacement of bracket relative to wire. Stainless steel (SS), cobalt-chromium (Co-Cr), nickel-titanium (NiTi), and beta-titanium (beta-Ti) wires of several sizes were tested in narrow single (0.050-inch), medium twin (0.130-inch) and wide twin (0.180-inch) stainless steel brackets in both 0.018- and 0.022-inch slots. The wires were ligated into the brackets with elastomeric ligatures. Bracket movement along the wire was implemented by means of a mechanical testing instrument, and frictional forces were measured by a compression cell and recorded on an X-Y recorder. beta-Ti and NiTi wires generated greater amounts of frictional forces than SS or Co-Cr wires did for most wire sizes. Increase in wire size generally resulted in increased bracket-wire friction. The wire size-alloy interaction on the magnitude of bracket-wire friction was statistically significant (p less than 0.005). With most wire sizes and alloys, narrow single brackets were associated with lower amounts of friction than wider brackets were. The levels of frictional forces in 0.018-inch brackets ranged from 49 gm with 0.016-inch SS wires in narrow single brackets to 336 gm with 0.017 x 0.025-inch beta-Ti wires in wide twin brackets. Similarly for 0.022-inch brackets, frictional forces ranged from 40 gm with 0.018-inch SS wires in narrow single brackets to 222 gm with 0.019 x 0.025-inch NiTi wires in wide twin brackets.     

Resistance to sliding of self-ligating brackets versus conventional stainless steel twin brackets with second-order angulation in the dry and wet (saliva) states.

The frictional properties of conventional stainless steel brackets that were coupled with rectangular stainless steel archwires and ligated with stainless steel ligature wires and the frictional properties of closed self-ligating brackets coupled with the same archwires were compared in terms of second-order angulation. The slides of these self-ligating brackets passively restrained the archwires within the slots. As a control, the frictional properties of the opened self-ligating brackets, which were ligated with stainless steel ligature wires, were measured. The resistance to sliding of the conventional brackets and the opened self-ligating brackets were measured at ligation forces ranging from 200 to 600 cN and at angles from -9 degrees to 9 degrees. The resistances to sliding of the closed self-ligating brackets were measured at the same angles, but no external ligation forces were applied. In the passive configuration, the conventional brackets exhibited similar frictional resistance as the opened self-ligating brackets, whereas the closed self-ligating brackets exhibited no friction. In the active configuration, all brackets exhibited increased resistance to sliding as the angulation increased. At all angles, the resistances to sliding of the closed self-ligating brackets were lower than those of the conventional brackets because of the absence of a ligation force when the slide restrained the archwire.     

Treatment time,outcome, and anchorage loss comparisons of self-ligating and conventional brackets

Objective:To compare the treatment time, outcome, and anchorage loss among orthodontic patients treated by self-ligating brackets (SLBs) and conventional brackets (CBs).Materials and Methods:A retrospective cohort study compared 34 patients (SLB group) treated by SmartClip brackets (3M Unitek, Monrovia, Calif) to 35 patients (CB group) treated by conventional preadjusted Victory series brackets (3M Unitek) and ligated by stainless steel wire ligatures. Pretreatment (T1) and posttreatment (T2) lateral cephalograms were traced and analyzed using Pancherz sagittal-occlusion analysis to obtain skeletal and dental changes in the maxilla and the mandible. The dental cast models were assessed by the Peer Assessment Rating (PAR) Index for the treatment outcomes.Results:The mean treatment time for SLBs (19.19 months) did not show a statistically significant difference from 21.25 months of CBs; the treatment time and pretreatment PAR scores were strongly correlated. There was no difference in anchorage loss between the SLB and CB groups. There were significant dental and skeletal changes among adolescent orthodontic patients regardless of the bracket used. The lingual inclination of the mandibular incisors in the CB group was 3.62° more than in the SLB group (P < .01).Conclusions:The treatment time and anchorage loss are not influenced by the type of bracket used. There are significant dental and skeletal changes among adolescent orthodontic patients regardless of the bracket used. There is significantly greater lingual inclination of mandibular incisors in the CB group than in the SLB group.