The influence of bracket design on frictional losses in the bracket/arch wire system

In arch guidad tooth movement, the essential role played by bracket configuration with respect to sliding friction has been recognized by the manufacturers, a fact which has had an increasing impact on the design and marketing of new bracket models in recent years. The aim of the present in-vitro study was to investigate the influence of different bracket designs on sliding mechanics.Five differently shaped stainless steel brackets (Discovery: Dentaurum, Damon SL: A-Company, Synergy: Rocky Mountain Orthodontics, Viazis bracket and Omni Arch appliance: GAC) were compared in the 0.022^II-slot system. The Orthodontic Measurement and Simulation System (OMSS) was used to quantify the difference between applied force (NiTi coil spring, 1.0 N) and orthodontically effective force and to determine leveling losses occurring during the sliding process in arch guided tooth movement. Simulated canine retraction was performed using continuous arch wires with the dimensions 0.019^II×0.025^II (Standard Steel, Unitek) and 0.020^II×0.020^II (Ideal Gold, GAC).     

Comparison of maxillary canine retraction with sliding mechanics and a retraction spring: a three-dimensional analysis based on a midpalatal orthodontic implant

The purpose of this study was to compare maxillary canine retraction with sliding mechanics and a Ricketts canine retraction spring, using a midpalatal orthodontic implant as a measuring reference. Eight patients (three males and five females) were examined. Because maximum posterior anchorage was required in all subjects, osseointegrated midpalatal implants were used. To examine tooth movement, impressions of the maxillary arch were made at each appointment and cast in die stone. A three dimensional (3D) surface-scanning system using a slit laser beam was used to measure the series of dental casts. The results demonstrated that 3D analysis of tooth movement based on a midpalatal orthodontic implant provided detailed information on canine retraction. The results also suggested that a canine retracting force of 1 N or less was more effective not only for sliding mechanics but also for the retraction spring. However, the sliding mechanics approach was superior to the retraction spring with regard to rotational control.     

正畸方丝转矩余隙角的研究

目的:研究正畸方丝在0.022英寸托槽内转矩余隙角的大小及影响因素。方法:用截距测量法与计算法对几种常用正畸方丝的余隙角进行测量与分析。结果:①钛镍方丝的余隙角明显大于不锈钢方丝;②钛镍方丝边缘斜面半径明显大于不锈钢方丝;③两种方法得到的余隙角没有统计学差异(P>0.05)。结论:①在0.022英寸托槽体系内,宽面为0.025英寸的不锈钢方丝及钛镍方丝每0.001英寸的余隙分别有4°、6°的余隙角;②不锈钢方丝与钛镍方丝余隙角的差异主要是两种材质弓丝边缘斜面不同造成的。钛镍方丝的边缘斜面大于不锈钢方丝。     

A comparison between friction and frictionless mechanics with a new typodont simulation system.

This study was designed to explore the differences between friction and frictionless mechanics for maxillary canine retraction with the use of a new typodont simulation system, the Calorific machine system. The unit was designed to observe the whole process of tooth movement and is composed of 3 parts: a temperature regulating system, electrothermodynamic teeth, and an artificial alveolar bone component. The efficiency of maxillary canine retraction was compared with the sliding mechanics (along a.016 x.022-in stainless steel labial arch and nickel-titanium closed coil spring) and a canine retraction spring. The patterns of tooth movement obtained with both of these mechanics were measured 5 times each. Friction mechanics were superior to frictionless mechanics in terms of rotational control and dimensional maintenance of the arch (P <.0001); frictionless mechanics were shown to be more effective at reducing tipping and extrusion (P <.0001). However, the observed differences between the 2 methods were relatively small in terms of their clinical significance, and no differences were found in anchorage control (P =.2078). In conclusion, this study indicated that friction and frictionless mechanics perform similarly.     

Numerical simulation of canine retraction by sliding mechanics.

BACKGROUND: Bone remodeling laws have been used to simulate the movement of a single tooth, but the calculations for simulating the movement of several teeth simultaneously are time-consuming. The purpose of this article is to discuss a method that allows the simulation of more complex tooth movements. METHODS: A 3-dimensional finite element method was used to simulate the orthodontic tooth movement (retraction) of a maxillary canine by sliding mechanics and any associated movement of the anchor teeth. Absorption and apposition of the alveolar bone were produced in proportion to the stress of the periodontal ligament. RESULTS: In a reference case, the canine was retracted by a 2N force with 0.016-in square wire. The frictional coefficient between wire and bracket was 0.2. The movement of both the canine and the anchor teeth could be calculated with the elastic deformation of wire. The canine tipped during the initial unsteady state and then moved bodily during the steady state. It became upright when the orthodontic force was removed. The anchor teeth moved in the steady state and tipped in the mesial direction. The decrease in applied force by friction was about 70%. The tipping of the canine decreased when the wire size was increased or when the applied force was decreased. CONCLUSIONS: Simple assumptions were used in this calculation to simulate orthodontic tooth movements. The calculated results were reasonable in mechanical considerations. This method might enable one to estimate various tooth movements clinically. However, precise comparisons between calculated and clinical results, and the improvement of the calculation model, are left for a future study.     

双槽沟托槽滑动阻力的实验研究

目的 评价模拟尖牙滑动时双槽沟托槽的滑动阻力,探讨临床应用双槽沟托槽的合适牵引力.方法 将粘有托槽的人工尖牙置于硅胶槽内,分别在10g、15g和20g力牵引下沿弓丝滑动.双槽沟托槽组中人工尖牙在双圆丝(直径0.016英寸和0.018英寸)支撑下移动.对照组为常规方丝托槽和方丝(0.016英寸×0.022英寸)组合.通过激光测距仪及相连计算机得到的牙齿移动速率,分析牙齿滑动时所受阻力的大小.结果 牵引力为10g力和15g力时,双槽沟托槽组平均移动速率较小.当牵引力增加到20g力,双槽沟托槽组平均速率大于常规托槽组.结论 在足够牵引力的作用下,双槽沟托槽配合双圆丝(直径0.016英寸和0.018英寸)组合的滑动阻力并不比常规托槽和0.016英寸×0.022英寸方丝组合大.     

Frictional resistance of ceramic and stainless steel orthodontic brackets

Frictional resistance of orthodontic appliances is recognized by most clinicians to be detrimental to tooth movement. The purpose of this study was to compare planar, static frictional forces among stainless steel and ceramic brackets. Both nitinol and stainless steel rectangular arch wires were passed freely through the slots of a pair of brackets from each type. Tests were carried out in air and in artificial saliva. A 300-gm load was suspended from the arch wire to simulate the normal force, and an incremental horizontal force was applied until movement of the arch wire was initiated. Under all conditions, the stainless steel brackets had lower coefficients of friction than the ceramic brackets. The stainless steel wire generated less friction than nitinol, and friction increased in the presence of artificial saliva in comparison with air alone. These results show that, under experimental conditions, ceramic brackets, nitinol arch wires, and saliva all increase static frictional resistance.     

Corrosion and calculus. How can the wire/bracket slide mechanics be improved?

Sliding mechanics are widely used in fixed orthodontic devices. Parasitic phenomena that block or slow the movement have, until now, been relatively neglected. The friction that appears at the interface of the wire/bracket/ligature opposes the free sliding action, necessary to allow the motor forces to displace the dental units that are guided on an appropriately shaped metal arch. There are three main causes that make unpredictable the control of orthodontic forces. The first one is the involuntary irregularities introduced onto the arches during their construction. The two others consist in factors blocking the sliding action. They can be unknown or misunderstood: the superficial corrosion of wires and brackets which affect the polished surface, and the appearance of adherent concretions due to hard and adherent tartar. This paper will discuss their involvement and describe the ways to improve the sliding effects.     

固定矫治器中切牙转矩的控制

目的　探讨切牙转矩定量的控制规律。方法　使用转矩测量仪 ,对横截面积为 0 4 6mm× 0 6 3mm的平直不锈钢丝与钛镍丝 ,7 0mm高垂直曲不锈钢丝 ,3 0mm长和 6 0mm长L形水平曲不锈钢丝 ,在单个 0 5 6mm中切牙托槽内的转矩力矩与扭转角度进行测量与分析。结果　(1)这些弓丝的抗扭刚度分别为 4 90 9、1 32 5、4 137、3 4 4 8和 3 0 2 4N·mm/度 ;(2 )转矩力矩达到2 0N·mm时 ,上述弓丝将分别扭转 19 14 3、36 832、19 85 1、2 1 812和 2 2 4 18度 ;(3)不锈钢丝和钛镍丝的转矩余隙角分别为 15 0 7度和 2 1 73度 ;(4)曲能起到降低不锈钢丝的抗扭刚度、增加弓丝弹性范围的作用 ,其中以水平曲的效用更优。结论　平直不锈钢丝不是控制切牙转矩的理想选择。曲 ,特别是水平曲 ,能显著降低弓丝的转矩刚度、增加弓丝弹性范围     

The influence of bracket design on frictional losses in the bracket/arch wire system

In arch guidad tooth movement, the essential role played by bracket configuration with respect to sliding friction has been recognized by the manufacturers, a fact which has had an increasing impact on the design and marketing of new bracket models in recent years. The aim of the present in-vitro study was to investigate the influence of different bracket designs on sliding mechanics.Five differently shaped stainless steel brackets (Discovery: Dentaurum, Damon SL: A-Company, Synergy: Rocky Mountain Orthodontics, Viazis bracket and Omni Arch appliance: GAC) were compared in the 0.022^II-slot system. The Orthodontic Measurement and Simulation System (OMSS) was used to quantify the difference between applied force (NiTi coil spring, 1.0 N) and orthodontically effective force and to determine leveling losses occurring during the sliding process in arch guided tooth movement. Simulated canine retraction was performed using continuous arch wires with the dimensions 0.019^II×0.025^II (Standard Steel, Unitek) and 0.020^II×0.020^II (Ideal Gold, GAC).Comparison of the brackets revealed friction-induced losses ranging from 20 to 70%, with clear-cut advantages resulting from the newly developed bracket types. However, an increased tendency towards leveling losses in terms of distal rotation (maximum 15°) or buccal root torque (maximum 20°) was recorded, especially with those brackets giving the arch wire increased mobility due to their shaping or lack of ligature wire.

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Der Einfluß des Bracketdesigns auf die Reibung zwischen Bracket und Führungsbogen

Zusammenfassung Bei der bogengeführten Zahnbewegung ist die Bracketkonfiguration im Rahmen der Gleitreibung ein nicht zu vernachlässigender Faktor, der inzwischen auch von den Herstellerfirmen erkannt wurde. Gestaltung und Vermarktung neuer Brackettypen werden hiervon zunehmend beeinflußt. In der vorliegenden In-vitro-Studie wurde die Bedeutung, die einer unterschiedlichen Bracketgestaltung auf das Gleiverhalten zukommt, untersucht.Fünf Brackettypen aus Stahl mit unterschiedlicher Formgebung (Discovery: Firma Dentaurum, Damon SL: A-Company, Synergy: Firma Rocky Mountain Orthodontics, Viazis-Bracket und Omni Arch Appliance: Firma GAC) wurden im 0.022^II-Slot-system gegenübergestellt. Zur quantitativen Bestimmung der Differenz von eingesetzter Kraft (NiTi-Zugfeder, 1,0 N) und orthodontisch wirksamer Kraft sowie der beim Gleitvorgang auftretenden Nivellierungsverluste wurde die bogengeführte Zahnbewegung mit Hilfe des orthodontischen Meß- und Simulations-Systems (OMSS) dargestellt. Die Eckzahnretraktion erfolgte am durchgehenden 0.019^II×0.025^II-Bogen (Standardstahl, Unitek) sowie am 0.020^II×0.020^II-Draht (Ideal Gold, GAC).Die Ergebnisse der In-vitro-Studie zeigten für die untersuchten Brackets einen stark unterschiedlichen Kraftverlust von 20 bis 70% der eingesetzten Kraft mit deutlichem Gleitvorteil für die neukonzipierten Brackettypen. Gleichzeitig war jedoch auch festzustellen, daß insbesondere bei den Brackets, bei denen aufgrund ihrer Geometrie sowie der teilweise fehlenden Drahtligatur eine erhöhte Manövrierfähigkeit am Bogen zu ermitteln war, mit verstärkten Nivellierungsverlusten im Sinne einer Distalrotation (maximal 15°) und eines bukkalen Wurzeltorques (maximal 20°) zu rechnen ist.

     

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.     

A comparative study of frictional forces between orthodontic brackets and arch wires

An in vitro study of simulated canine retraction was undertaken to evaluate the difference in frictional resistance between stainless steel arch wires and steel and ceramic brackets with elastomeric, steel, and self-ligation. Each bracket slot was 0.018 x 0.025 inch. The arch wires used were 0.014-inch, 0.016-inch, 0.018-inch, 0.016 x 0.016-inch, and 0.016 x 0.22-inch stainless steel. A testing apparatus was designed to attempt to simulate the clinical situation in which teeth tip slightly while they slide along the arch wire. Under these testing conditions, the self-ligating steel bracket did not demonstrate less friction than the elastic or steel-ligated stainless steel brackets. For most wire sizes, elastomer-ligated ceramic brackets demonstrated the greatest friction when compared with other bracket/ligation technique combinations. The clinical significance of this study becomes apparent when stainless steel brackets are used on the posterior teeth and ceramic brackets are used on the anterior teeth. If sliding mechanics are used, the anterior teeth may be more resistant to movement than the posterior teeth because of the greater friction of the ceramic brackets. This could result in more posterior anchorage loss than would be expected if only one type of bracket were used.     

外展曲与支抗磨牙所受舌向力的关系

目的　观察拉尖牙向远中移动时 ,在不同规格的弓丝作用下 ,牵引力对支抗磨牙所产生的舌向分力的大小以及在不同磨牙外展曲宽度下该牵引力舌向分力的大小。方法　利用与北京大学力学系合作研制的力测量仪在Typodont专用蜡上测量使用不同规格、不同刚度的弓丝 [0 4 0mm、0 4 5mm的不锈钢圆丝 ,0 4 0mm、0 4 5mm的澳丝以及 0 4 1mm× 0 5 6mm (0 0 16英寸× 0 0 2 2英寸 )、0 4 6mm× 0 6 3mm(0 0 17英寸× 0 0 2 5英寸 )的不锈钢方丝 ],分别在不同的磨牙外展曲宽度 (1mm、2mm、3mm)下 ,支抗磨牙受到的 15 0 g沿磨牙颊面管牵引钩至尖牙托槽远中翼中点方向的拉尖牙向远中移动力所产生的舌向分力。结果　 (1) 15 0 g拉尖牙向远中移动力会使支抗磨牙受到舌向分力。 (2 )支抗磨牙受到的牵引力的舌向分力随弓丝粗度和刚度的增加而减少 ,弓丝抵抗磨牙所受到的舌侧力作用与弓丝的刚度、粗度成正比。 (3)支抗磨牙受到的牵引力的舌向分力随磨牙外展曲宽度的增加而减少且二者间呈线性关系。结论　拉尖牙向远中移动时支抗磨牙受到舌向分力 ,为避免磨牙向舌侧移动 ,应选择较大刚度且较粗的弓丝或适当加大磨牙外展曲。     

Begg-edgewise diagnosis-determined totally individualized orthodontic technique: foundations, description, and rationale

This article presents an appliance system designed to facilitate efficient treatment by the use of the biomechanical approach considered most suitable by the orthodontist for the individual patient. The system described uses narrow, single brackets with 0.022 X 0.028 inch edgewise arch wire slots and 0.020 X 0.020 inch vertical slots for various auxiliaries. There are five brackets that differ only in the torque of the arch wire slot-0 degree, 5 degrees, 10 degrees, 15 degrees, and 20 degrees. Thus, an appropriate bracket can be selected for any tooth in any situation. The brackets and bonding pads are small in all dimensions to ensure optimal appearance and interbracket arch wire spans and minimal lip and cheek irritation. This also lessens occlusal interference, enamel surface involved in bonding, and problems with gingival proximity and oral hygiene. The basic buccal tubes are conventional 4.5 mm long, 0.022 X 0.028 inch torqued edgewise tubes. A buccal tube assembly with a similar additional rectangular tube carried diagonally at a 15 degree angle across the buccal surface of the basic tube (its mesial end pointing gingivally) is used in extraction cases with deep overbites or moderate-to-severe anchorage requirements. The angulated outer tube carries the main (working) arch wire during the bite-opening and retraction phases of treatment. A rectangular sectional wire in the inner tube and second premolar bracket locks the molar and premolar teeth together so that neither can tip independently. As a unit they provide anchorage for bite opening and retraction. The gingivally positioned and angulated outer tube directs the arch wire out of danger of distortion from mastication and provides a built-in biteopening effect. The molar and premolar teeth, in effect, become a single large tooth with its center of resistance (CR) further mesial than the CR of the molar. Sectional wires result in a more favorable system of moments created by arch wires and elastics. This delivers more intrusive force to the incisors with less tendency to tip the anchor units. The appliance provides the orthodontist with an extensive range of options in treatment mechanics--from anchorage conservation and rapid movement of limited tipping by light forces to translation or stabilization with precise three-dimensional control.     

Study on frictional characteristics of KB horizontal brackets. A comparative study of kinetic frictional forces to be caused between various kinds of brackets and wires

KB horizontal brackets were designed to tip no more than 6 degrees at the maximum. This tipping amount is based on the idea of reducing friction between a wire and brackets to allow the effective tooth movement of the Begg technique even with horizontally long brackets, and does not originate in the concept of carrying out tipping movement. Thereon, experimental measurements by use of Rheometer were conducted to review for comparison of the kinetic frictional forces caused between various wires and the following four types of brackets; KB horizontal brackets, Tip edge brackets, Straight edge brackets and Begg brackets. 1. In case of utilizing ribbon arch wires and rectangular wires, no significant difference was acknowledged among Tip edge, KB horizontal and Straight edge brackets. 2. There proved to be a reduction in the kinetic frictional forces by incorporating tip into the edgewise slots, when using smaller dimensions of the wires which call for the effective tooth movement, however, Begg brackets (in conjunction with Ordinary T-pins and/or Safety T-pins) showed the small value which is far less than that of the three kinds of brackets.     

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

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

Combination anchorage technique: an update of current mechanics

Experience and advances in design and technique have greatly enhanced combination orthodontic techniques during the past 5 years. Improvements have made the delivery of treatment more effective and reduced the problems with appliance adjustment and esthetics. Some of these improvements are in the bracket itself, which has been modified for efficiency and esthetics. A modification of treatment technique by the addition of tandem wires, stabilizing arch wires, Dual Flex arch wires, and sectional wires have increased the movement capabilities and anchorage control. A technique of orthodontic mechanics has evolved that is called combination anchorage technique (CAT). The technique is designed to broaden the treatment effectiveness of the orthodontist by providing a combination of orthodontic technical capabilities. Use of the two different bracket slots provides a simple and efficient means to vary (1) anchorage (dynamic or static), (2) movement (tipping or bodily), (3) technique (light wire or straight wire), (4) resistance (one tooth or multiple teeth), and (5) treatment compensation (skeletal or dental).     

The Frictional Behavior of Coated Guiding Archwires

BACKGROUND: The vast range of orthodontic wires made of different alloys makes it increasingly difficult for orthodontists to judge them. Coated orthodontic wires form a group of innovative guiding archwires. MATERIAL AND METHODS: In the present in vitro study the frictional behavior of eight coated wires of different dimensions was investigated in archwire-guided canine retraction in the upper jaw. For this purpose five superelastic nickel titanium alloy wires (Titanol Low Force River Finish Gold and Gold 2: Forestadent, Pforzheim Germany; Titanol Superelastic tooth colored: Forestadent, Pforzheim Germany; BioForce Sentalloy Ionguard: GAC, Central Islip, NY, USA; NITI Imagination: GAC, Central Islip, NY, USA), two beta-titanium wires (TMA Low Friction Ionguard: Ormco, Glendora, CA, USA; TMA Low Friction Ionguard Purple: Ormco, Glendora, CA, USA), and one steel wire (Stainless steel Imagination: GAC, Central Islip, NY, USA) were selected. The coatings were made of Teflon or polyethylene, and by ion implantation. Three uncoated archwires (Rematitan Lite Dimple: Dentaurum, Pforzheim, German; Titanol Low Force River Finish: Forestadent, Pforzheim, Germany; BioForce Sentalloy: GAC, Central Islip, NY, USA) were used for comparison purposes. The force losses due to friction were measured using the Orthodontic Measurement and Simulation System (OMSS). RESULTS: The results indicated that all coatings can reduce frictional losses compared with an uncoated reference wire by the same manufacturer. Measured frictional losses ranged from 48.3-6.1%, with the Teflon coatings reducing the frictional losses to less than 10% in some cases. CONCLUSION: An unequivocal correlation between the surface roughness and frictional forces of the wires could not be verified by scanning electron microscopy.     

Comparative friction of orthodontic wires under dry and wet conditions

Kinetic coefficients of friction for stainless steel, beta-titanium, nickel-titanium, and cobalt-chromium arch wires were measured on a smooth stainless steel or Teflon surface. A universal materials testing instrument was used to pull 0.017 X 0.025-inch rectangular arch wires through a pneumatically controlled binding surface. Classical friction relationships were evaluated by varying applied normal force--similar to ligature tie force--via this pneumatic control. Coefficients of friction were determined under dry and wet (artificial saliva) conditions. Frictional force values, and thus coefficients of friction, were found to increase with increasing normal force for all materials. Beta-titanium and stainless steel wires sliding against stainless steel, and stainless steel wire on Teflon consistently exhibited the lowest dry friction values. Artificial saliva increased friction for stainless steel, beta-titanium, and nickel-titanium wires sliding against stainless steel. Artificial saliva did not increase friction for cobalt chromium, stainless steel sliding against stainless steel, or stainless steel wire on Teflon compared to the dry condition. Stainless steel and beta-titanium wires sliding against stainless steel and stainless steel wire on Teflon showed the lowest friction values for the wet condition.