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.     

Self-Ligation Esthetic Brackets with Low Frictional Resistance

Objective:To test the frictional resistance forces (FRS) generated between several archwires and (1) interactive self-ligating (ISL) brackets and (2) conventionally ligated (CL) brackets.Materials and Methods:Frictional forces produced between three different archwire combinations and self-ligating (SL) brackets (ceramic and metal-slot or all-metal) and CL brackets (metal or ceramic) were evaluated in a dry environment. The three ISL brackets tested were In-Ovation-C, In-Ovation-R, and Damon 3. The three CL brackets were Mystique with Neo Clip, Clarity, and Ovation. Each bracket was tested with 0.020″ SS, 0.019″ × 0.025″ SS and 0.018″ × 0.018″ coated SS.Results:The ISL brackets generally exhibited the lowest frictional forces irrespective of the bracket material and the wire size, and CL brackets exhibited consistently higher frictional forces. Mystique with Neo Clip produced the lowest frictional resistance of all brackets. The In-Ovation-C brackets demonstrated significantly lower frictional resistance than the SL brackets In-Ovation-R and Damon 3 as well as the CL brackets Clarity and Ovation.Conclusions:The ISL ceramic brackets produced the lowest frictional resistance of all the self-ligating brackets. The CL ceramic brackets produced the greatest friction.     

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.     

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。     

Dimensional accuracy of ceramic self-ligating brackets and estimates of theoretical torsional play

Objective:To ascertain the dimensional accuracies of some commonly used ceramic self-ligation brackets and the amount of torsional play in various bracket–archwire combinations.Materials and Methods:Four types of 0.022-inch slot ceramic self-ligating brackets (upper right central incisor), three types of 0.018-inch ceramic self-ligating brackets (upper right central incisor), and three types of rectangular archwires (0.016 × 0.022-inch beta-titanium [TMA] (Ormco, Orange, Calif), 0.016 × 0.022-inch stainless steel [SS] (Ortho Technology, Tampa, Fla), and 0.019 × 0.025-inch SS (Ortho Technology)) were measured using a stereomicroscope to determine slot widths and wire cross-sectional dimensions. The mean acquired dimensions of the brackets and wires were applied to an equation devised by Meling to estimate torsional play angle (γ).Results:In all bracket systems, the slot tops were significantly wider than the slot bases (P < .001), yielding a divergent slot profile. Clarity-SLs (3M Unitek, Monrovia, Calif) showed the greatest divergence among the 0.022-inch brackets, and Clippy-Cs (Tomy, Futaba, Fukushima, Japan) among the 0.018-inch brackets. The Damon Clear (Ormco) bracket had the smallest dimensional error (0.542%), whereas the 0.022-inch Empower Clear (American Orthodontics, Sheboygan, Wis) bracket had the largest (3.585%).Conclusions:The largest amount of theoretical play is observed using the Empower Clear (American Orthodontics) 0.022-inch bracket combined with the 0.016 × 0.022-inch TMA wire (Ormco), whereas the least amount occurs using the 0.018 Clippy-C (Tomy) combined with 0.016 × 0.022-inch SS wire (Ortho Technology).     

Canine retraction rate with self-ligating brackets vs conventional edgewise brackets

Objective:To compare the rates of retraction down an archwire of maxillary canine teeth when bracketed with a self-ligating bracket was used on one side and a conventional bracket on the other.Materials and Methods:In 43 patients requiring maxillary premolar extraction, a self-ligating bracket (Damon3, SmartClip) was used on the maxillary canine on one side and a conventional bracket (Victory Series) on the other. The teeth were retracted down a 0.018-inch stainless steel archwire, using a medium Sentalloy retraction spring (150 g). The rates of retraction were analyzed using a paired t-test.Results:The mean movement per 28 days for the conventional bracket was 1.17 mm. For the Damon bracket it was 0.9 mm and for the SmartClip bracket it was 1.10 mm. The differences between the conventional and self-ligating brackets were statistically significant: paired t-test, SmartClip, P < .0043; Damon3, P < .0001).Conclusion:The retraction rate is faster with the conventional bracket, probably because of the narrower bracket width of the self-ligating brackets.     

SmartClip自锁矫治器排齐效果的研究

目的 探讨使用SmartClip自锁矫治器与传统结扎式矫治器排齐拥挤上颌牙弓的效能是否有差异。方法 选取48例牙列不齐指数>5mm、年龄12～15岁、采取拔除上颌第一前磨牙治疗的患者,按随机对照原则抽选使用SmartClip自锁矫治器或传统结扎式矫治器。结果 使用SPSS15.0进行分析。结果 排齐速度与初始不齐指数相关。矫治5周及10周时,自锁组前牙不齐指数及两侧拔牙间隙的减小、前段弓长的增加大于传统组,两组间有显著性差异(P<0.05)。自锁组排齐速度快于传统组。结论 使用SmartClip自锁托槽可以缩短、中重度拥挤采取拔牙矫治患者牙弓的排齐时间。     

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.     

A prospective randomized split-mouth study on pain experience during chairside archwire manipulation in self-ligating and conventional brackets

Objective:To investigate patient discomfort during archwire engagement and disengagement in patients treated with self-ligating and conventional brackets using a split-mouth design.Materials and Methods:Eighteen consecutive patients (15 female, 3 male; age: 22.2 ± 6.4 years) who requested treatment with fixed orthodontic appliances were randomly assigned for bonding with SmartClip self-ligating brackets on one side of the dentition and conventional standard edgewise brackets on the other. During the course of treatment, patients rated the discomfort experienced during every archwire engagement and disengagement using a numeric rating scale. Results were evaluated for round and rectangular nickel titanium and rectangular stainless steel, titanium molybdenum, and Elgiloy archwires. Patients also rated their overall experience retrospectively for both bracket systems.Results:Regardless of archwire type, disengagement was rated as being significantly more painful on the SmartClip side (P  =  .027). For rigid, rectangular archwires, engagement and disengagement were rated as being significantly more painful on the SmartClip side (P  =  .031; P  =  .004). Retrospective ratings favored conventional brackets beyond ratings recorded during treatment.Conclusion:Engagement and disengagement of rigid rectangular archwires caused more pain with SmartClip self-ligating brackets than with conventional ones. Careful archwire manipulation and patience during full alignment are essential for limiting chairside pain. Low pain levels will help ensure treatment satisfaction and compliance.     

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.     

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。     

Comparison of resistance to sliding between different self-ligating brackets with second-order angulation in the dry and saliva states.

Resistance to sliding was investigated for 3 self-ligating brackets having passive slides and 3 self-ligating brackets having active clips. Four of these products are currently marketed, and 2 are of historic interest. For all cases, an 0.018 x 0.025-in stainless steel archwire was drawn through each bracket at a rate of 10 mm/min over a distance of 2.5 mm. For each bracket, the resistances to sliding were measured at 14 second-order angulations, which ranged from -9 degrees to +9 degrees. Both the dry and the wet (human saliva) states were evaluated at 34 degrees C. From dimensional measurements, the critical contact angles for binding were determined for all products and ranged from 3 degrees to 5 degrees. Below each characteristic critical angle, brackets with passive slides exhibited negligible friction; brackets with active clips exhibited frictional forces as great as 50 cN (50 g). Above each critical angle, all brackets had elastic binding forces that increased at similar rates as angulation increased and were independent of bracket design. Generally speaking, at second-order angulations that exceeded the critical angle, brackets with active clips that had a low critical angle had more resistance to sliding than did brackets with active clips that had a higher critical angle. Brackets with passive slides that had a high critical angle exhibited the lowest resistance to sliding, but could do so at a cost of some loss of control. Nonetheless, self-ligating brackets represent a compromise between friction and control; ie, self-ligating brackets produce frictional forces that are more reproducible than do conventionally ligated stainless steel brackets but without the potential control problems associated with Begg-style brackets.     

The effect of ligation method on friction in sliding mechanics.

During orthodontic tooth movement with the preadjusted edgewise system, friction generated at the bracket/archwire interface tends to impede the desired movement. The method of ligation is an important contributor to this frictional force. This in vitro study investigated the effect of ligation method on friction and evaluated the efficacy of the new slick elastomeric modules from TP Orthodontics (La Porte, Ind), which are claimed to reduce friction at the module/wire interface. Slick modules were compared with regular nonslick modules, stainless steel ligatures, and the SPEED self-ligating bracket system (Strite Industries, Cambridge, Ontario, Canada). The effect of using slick modules with metal-reinforced ceramic (Clarity, 3M Unitek, Monrovia, Calif) and miniature brackets (Minitwin, 3M Unitek) was also examined. Results showed that, when considering tooth movement along a 0.019 x 0.025-in stainless steel archwire, saliva-lubricated slick modules can reduce static friction at the module/archwire interface by up to 60%, regardless of the bracket system. The SPEED brackets produced the lowest friction compared with the 3 other tested bracket systems when regular modules were used. The use of slick modules, however, with all of the ligated bracket types tested significantly reduced friction to below the values recorded in the SPEED groups. Loosely tied stainless steel ligatures were found to generate the least friction.     

Different bracket–archwire combinations for simulated correction of two-dimensional tooth malalignment

Objectives

Self-ligating brackets are widely believed to be more effective in clinical use and to involve less friction and force. Thus, the goal of this in vitro investigation was to experimentally assess the effectiveness of different bracket–archwire combinations and the force levels exerted in two-dimensional direction during correction of tooth malalignment. An important aspect of this objective was to determine whether the behaviors of conventional bracket systems with an elastic or steel ligature differ from that of self-ligating brackets.

Materials and methods

Three conventional (Mini Taurus®, RMO; Synergy®, RMO; Victory Series?, 3M Unitek) and three self-ligating bracket systems (Speed?, Strite; Smart Clip?, 3M Unitek; Time 3, American Orthodontics) were analyzed. All brackets had 0.018-inch (0.46-mm) slots and—except for the self-ligating brackets—were tested with both a steel ligature (0.25 mm; Remanium, Dentaurum) and an elastic rubber ligature (1.3 mm in diameter; Dentalastics, Dentaurum). They were fitted with four different round wires: a 0.30-mm stainless steel (3M Unitek), 0.38-mm stainless steel coaxial (Advanced Orthodontics), 0.30-mm Thermalloy NiTi (RMO), and 0.30-mm Orthonol NiTi (RMO) archwire. The orthodontic measurement and simulation system (OMSS) was used to simulate a two-dimensional (2 mm of infraocclusion and 2 mm of vestibular displacement) malalignment of tooth 21 inserted in a resin replica of a Frasaco model. Four brackets of the same type were assessed and four individual measurements taken per bracket to analyze initial force systems and corrective malalignment outcomes.

Results

The initial force systems and tooth movements varied distinctly between the different material combinations in conjunction with the ligation systems and archwire types used. The force systems generated were readily reproducible across individual measurements. Leveling outcomes and force systems between conventional steel-ligated and self-ligating brackets coincided in most cases. Both of these device configurations corrected the malalignment by 78–99?% on average. Rubber-ligated conventional brackets, by contrast, performed significantly worse due to exertion of significantly higher forces and 60?% less of a leveling effect.

Conclusion

Our investigation demonstrates that both conventional steel-ligated brackets and self-ligating brackets, which are highlighted in the literature as highly efficient systems, lead to equivalent corrective outcomes in the treatment of tooth malalignments.     

Adhesive performance of precoated brackets after expiration

Objective:To evaluate adhesive performance in terms of debonding forces of precoated metal and ceramic brackets 4 years after expiration.Materials and Methods:Buccal and lingual surfaces of embedded extracted maxillary premolars were etched with 34% Tooth Conditioner Gel (Dentsply Caulk, Milford, Del), rinsed, and dried. Transbond MIP (3M Unitek, Monrovia, Calif) was applied prior to placing adhesive precoated brackets (APC II Victory stainless steel and APC Plus Clarity ceramic brackets, 3M Unitek). The preexpiration brackets had 29–35 months before, and the postexpiration brackets were 45–52 months past, their expiration dates. Sample size was 17–21 per group. Debonding forces were determined by subjecting the bonded brackets to a shear force in a universal testing machine. Debonding forces were compared using two-way ANOVA. Debonded surfaces were examined under a stereomicroscope to determine failure modes, which were compared using the chi-square test.Results:No statistically significant difference was found in debonding forces (P  =  .8581) or failure modes (P  =  .4538) between expired and unexpired brackets. Metal brackets required statistically significantly higher debonding forces than did ceramic brackets (P  =  .0001). For both expired and unexpired brackets, failure modes were mostly cohesive in the adhesive layer for ceramic brackets, and mixed between adhesive and cohesive failure in the adhesive layer for metal brackets.Conclusions:Adhesive precoated brackets did not have any reduction in enamel-adhesion properties up to 4 years after their expiration date. Extended shelf life testing for precoated dental brackets may be worth considering.     

Active and passive self-ligation—a myth?

Objective: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.Materials and Methods: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.Results: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.Conclusions: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.     

Debris and friction of self-ligating and conventional orthodontic brackets after clinical use

Objective:To compare the degree of debris and friction of conventional and self-ligating orthodontic brackets before and after clinical use.Materials and Methods:Two sets of three conventional and self-ligating brackets were bonded from the first molar to the first premolar in eight individuals, for a total of 16 sets per type of brackets. A passive segment of 0.019 × 0.025-inch stainless steel archwire was inserted into each group of brackets. Frictional force and debris level were evaluated as received and after 8 weeks of intraoral exposure. Two-way analysis of variance and Wilcoxon signed-rank test were applied at P < .05.Results:After the intraoral exposure, there was a significant increase of debris accumulation in both systems of brackets (P < .05). However, the self-ligating brackets showed a higher amount of debris compared with the conventional brackets. The frictional force in conventional brackets was significantly higher when compared with self-ligating brackets before clinical use (P < .001). Clinical exposure for 8 weeks provided a significant increase of friction (P < .001) on both systems. In the self-ligating system, the mean of friction increase was 0.21 N (191%), while 0.52 N (47.2%) was observed for the conventional system.Conclusion:Self-ligating and conventional brackets, when exposed to the intraoral environment, showed a significant increase in frictional force during the sliding mechanics. Debris accumulation was higher for the self-ligating system.