減少矯正器與矯正線之間的摩擦力有利於施予牙齒適當矯正力，避免錨定喪失，及有效率的牙齒移動。雖然已有研究報告比較矯正摩擦阻力相關的參數，包括：材質、矯正線尺寸、矯正結紮方式、液體媒介、及表面粗糙度。然而，目前很少實驗探討關於矯正器溝槽的設計，及口內溫度改變對摩擦阻力的影響。本實驗的目的是要分析三類重要參數對矯正摩擦阻力的影響：分別為矯正器特性(結紮方式及溝槽設計)，矯正線特性(矯正線材質)，以及口內環境因子(唾液及溫度變化)。本實驗共測試三類矯正系統，包括傳統結紮方式的矯正系統，主動及被動式自鎖式矯正系統；兩種矯正線，包括27oC含銅鎳鈦矯正線與沃斯田鐵相矯正線。實驗用模型包含五顆矯正器，位於中央的矯正器可往牙齦面位移五釐米以模擬臨床上高位犬齒的狀況。利用溫控裝置將實驗環境設定三種溫度(20oC, 37oC, 55oC) ；並以人工唾液來模擬口內潮濕狀態。在摩擦力實驗前後使用掃描式電子顯微鏡 (SEM) 檢視矯正器溝槽表面形態及利用X射線能量散佈分析儀 (EDS)進行矯正器溝槽表面成分分析。摩擦力測試分成兩階段，第一階段實驗：五顆矯正器呈直線排列以測試不同結紮方式對摩擦力產生的影響；第二階段實驗：中央的矯正器往牙齦面位移三釐米以模擬binding效應。實驗結果顯示，傳統式矯正器產生的摩擦力比自鎖式矯正器大且有顯著差異，可歸因於較大的結紮力以及無斜面溝槽設計。主動式矯正器產生的摩擦阻力較其他被動式矯正器產生的摩擦阻力大主要是因為斜面溝槽設計的大小。從SEM觀察結果發現，斜面溝槽的大小、摩擦力大小及矯正器溝槽表面的刮痕深淺呈現相關性。在binding狀況下，27oC含銅鎳鈦矯正線產生的摩擦阻力小於沃斯田鐵相矯正線。在有人工唾液狀態下的摩擦力大於乾燥狀態下的摩擦力，且溫度愈高摩擦力顯著增大。本實驗全面的探討影響矯正摩擦力的變因，期望能提供臨床矯正醫師關於矯正摩擦力的認識及選擇矯正器、矯正線的相關參考。

Reducing frictional force is essential for optimal orthodontic force, prevention of anchorage loss, and effective tooth movement. Several parameters which related to the friction resistance had been widely investigated, including material, wire dimension, methods of ligation, fluid media, and surface roughness. However, only few studies mentioned about the effect of slot design, and alterations in oral temperature. The aim of this study is to verify the influence of bracket properties (types of ligation, slot design), archwire properties (material), and oral environmental factors (saliva, temperature alterations) to the frictional resistance in orthodontic sliding. Three types of brackets were tested: conventional bracket, passive and active self-ligating brackets (PSLB & ASLB). Two alloys of 0.014” archwire were included: Copper-NiTi 27oC and A-NiTi. An experimental model composed of five brackets was designed. The middle bracket could be displaced 5 mm in order to mimic clinical “high-canine” malocclusion. Frictional experiments were performed with a universal testing machine under temperature controlling device in three temperature conditions (20oC, 37oC, 55oC) in the dry state, and in the wet state (artificial saliva). The surface of bracket slot was observed by SEM before and after frictional tests, and the composition of bracket slot was examined by EDS. Two types of friction test were set. First, at 0-mm position, five brackets were well aligned to simulate the passive configuration. Second, the center bracket was displaced 3-mm in the gingival direction to simulate the binding effect. The results showed that conventional brackets showed significant higher levels of frictional force when compared with active and passive self-ligating brackets because of the heavy ligation force and smallest bevel angle; The Clippy (ASLB) brackets showed significant higher levels of frictional force among four self-ligating brackets. A correlation could be found between the level of frictional force, the size of bevel angle, and the surface scratched. Copper-NiTi 27oC showed lower levels of frictional force than A-NiTi in active configuration. Frictional force is higher in the wet state than in the dry state. The frictional force was increased as the temperature rose from 20oC to 55oC. By thoroughly analyzing and comparing the parameters of frictional resistance, we hope to provide orthodontists a better understanding of the biomechanics, material science, and frictional behavior of orthodontic appliances.

1. Rossouw P.E. Friction: An Overview. Semin Orthod 2003;9:218-222.
2. Graber TM, Vanarsdall RL, Vig KWL. Orthodotics: Current principles and techniques. 4th ed. 2005; Elesevier Mosby: Missouri.
3. Santoro M. Nickel-titanium alloys: Stress-related temperature transitional range. Am J Orthod Dentofac Orthop 2000;118:685-692.
4. Yoneyama T. Miyazaki S. Shape memory alloys for biomedical applications. 2009;Woodhead poblishing : Cambridge.
5. Kusy RP., Whitley JQ. Friction Between Different Wire-Bracket Configurations and Materials. Semin Orthod 1997;3:166-177.
6. Airoldi G., Riva G,Vanelli M.,Fillippi V., Garattini G. Oral environment temperature changes induced by cold/hot liquid intake. Am J Orthod Dentofac Orthop 1997;112:58-63.
7. Meling T. The effect of short-term temperature changes on superelastic nickel-titanium archwires activated in orthodontic bending. Am J Orthod Dentofac Orthop 2001;119:263-273.
8. Nishio C. et al. In vitro evaluation of frictional forces between archwires and ceramic brackets. Am J Orthod Dentofac Orthop 2004;125:56-64.
9. Bazakidou E. et al. Evaluation of frictional resistance in esthetic brackets. Am J Orthod Dentofac Orthop 1997;112:138-144.
10. Saunders CR., Kusy RP. Surface topography and frictional characteristics of ceramic brackets. Am J Orthod Dentofac Orthop 1994;106:76-87.
11. Kusy RP., Whitley JQ. Comparison of frictional coefficients for selected archwire-bracket slot combination in the dry and wet state. Angle Orthod 1991; 61:293-302.
12. Matarese G. et al. Evaluation of frictional forces during dental alignment: An experimental model with 3 nonleveled brackets. Am J Orthod Dentofac Orthop 2008;133: 708-715.
13. Tecco S. et al. An in vitro investigation of the influence of self-ligating brackets, low friction ligatures, and archwire on frictional resistance. Eur J Orthod 2007; 29: 390-397.
14. Thorstenson G. Effect of archwire size and material on the resistance to sliding of self-ligating brackets with second-order angulation in the dry state. Am J Orthod Dentofac Orthop 2002;122:295-305.
15. Kim T. Comparison of frictional forces during the initial leveling stage in various combinations of self-ligating brackets and archwires with a custom-designed typodont system. Am J Orthod Dentofac Orthopedics 2008;133:187.e15-187.e24.
16. Henao SP, Kusy RP. Evaluation of the Frictional Resistance of Conventional and Self-ligating Bracket Designs Using Standardized Archwires and Dental Typodonts. Angle orthod 2004;74:202-211.
17. Kusy RP., Whitley JQ. Surface roughness of orthodontic wire. Angle orthod 1988: 33-45.
18. Wichelhaus A. et al. The effect of surface treatment and clinical use on friction in NiTi orthodontic wires. Dent Mater 2005;21: 938-945.
19. Doshi UH., Bhad-Patil WA. Static frictional force and surface roughness of various bracket and wire combinations. Am J Orthod Dentofa Orthop 2011.;139: 74-79.
20. Sims APT. et al. A comparison of the forces required to produce tooth in vitro using two self-ligating brackets and a pre-adjusted bracket employing two types of ligation. Euro J Orthod 1993;15:377-385.
21. Shivapuja PK., Berger J. A comparative study of conventional ligation and self-ligation bracket systems. Am J Orthod Dentofac Orthop 1994;106:472-80.
22. Thorstenson GA. Resistance to sliding of self-ligating brackets versus conventional stainless steel twin brackets with second-order angulation in the dry and wet (saliva) states. Am J Orthod Dentofac Orthop 2001;120:361-370.
23. Thorstenson GA., Kusy RP. 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. Angle orthod 2003;73:418-430.
24. Thorstenson GA. Comparison of resistance to sliding between different self-ligating brackets with second-order angulation in the dry and saliva states. Am J Orthod Dentofac Orthop 2002;121: 472-482.
25. Kusy RP., Whitley JQ. Influence of fluid media on the fricitonal coefficients in orthodontic sliding. Semin Orthod 2003;9: 281-289.
26. Kusy RP., Schafter DL. Effect of salivary viscosity on frictional coefficients of orthodontic archwire/bracket couples. J Mater Sci: Mater in Med 1995;6: 390-395.
27. Rossouw P., Kamelchuk L., Kusy RP. A Fundamental Review of Variables Associated with Low Velocity Frictional Dynamics. Semin Orthod 2003;9: 223-235.
28. Persson, BNJ., Tosatti E. Physics of Sliding Friction. 1995;Kluwer Academic Publishers: Netherlands.
29. Krishnan V., Davidovitch ZE. Cellular, molecular, and tissue-level reactions to orthodontic force. Am J Orthod Dentofac Orthop 2006;129: 469.e1-469.e32.
30. Whitley JQ., Kusy RP. Influence of archwire and bracket dimensions on sliding mechanism: derivations and determinations of the critical contact angles for binding. Euro J Orthod 1999;21: 199-208.
31. Kusy RP. A review of contemporary archwires:their properties and charateristics. Angle Orthod 1997;67: 197-208.
32. Burstone C., Morton J. Chinese Ni-Ti wire: a new orthodontic alloy. Am J Orthod 1985;87:445-52.
33. Miura F. et al. The superelastic properties of the Japanese Ni-Ti alloy wire for use in orthodontics. Am J Orthod Dentofac Orthop 1986;90: 1-10.
34. Bradley TG., Brantley WA., Culbertson B.M. Differential scanning calorimetry (DSC) analyses of superelastic and nonsuperelastic nickel-titanium orthodontic wires. Am J Orthod Dentofac Orthop 1996;109: 589-597.
35. Yeh C. et al. In-vitro evaluation of frictional resistance between brackets with passive-ligation designs. Am J Orthod Dentofac Orthop 2007;131: 704.e11-704.e22.
36. Stolzenberg J. The Russell attachment and its improved advantages. Int J Orthod Dent Children 1935;21: 837-840.
37. Wildman A. Round table-the Edgelok bracket. J Clin Orthod 1972;6: 613-623.
38. Hanson G. The SPEED system: a report on the development od a new edgewise appliance. Am J Orthod 1980;78: 243-265.
39. Damon D. The Damon low-friction bracket: a biologically compatible straight-wire system. J Clin Orthod 1998; 32: 670-681.
40. Voudouris JC. Interactive edgewise mechanisms: Form and function comparison with conventional edgewise brackets. Am J Orthod Dentofac Orthop 1997;111: 119-40.
41. Kusy RP. Schafer DL. Effect of salivary viscosity on frictional coefficients of orthodontic archwire/bracket couples. J Mater Sci: Mater in Med 1995;6: 390-395.
42. Widu F. et al. Corrosion and biocompatibility of orthodontic wire. J Mater Sci: Mater in Med 1999;10: 275-81.
43. Fourie Z., Özcan M., Sandham A. Effect of dental arch convexity and type of archwire on frictional forces. Am J Orthod Dentofac Orthop 2009;136: 14.e1-14.e7.
44. Santoro M. Pseudoelasticity and thermoelasticity of nickel-titanium alloys: A clinically oriented review. Part II: Deactivation forces. Am J Orthod Dentofac Orthop 2001;119: 594-603.
45. Gil F., Planell J. Effect of Copper Addition on the Superelastic Behavior of Ni-Ti Shape Memory Alloys for Orthodontic Applications. J Biomed Mater Res (Appl Biomater) 1999;48: 682-688.
46. Nakano H. et al. Mechanical properties of several nickel-titanium alloy wires in three-point bending tests. Am J Orthod DentofacOrthop 1999;115: 390-395.
47. Henao SP., Kusy RP. Frictional Evaluations of Dental Typodont Models Using Four Self-ligating Designs and a Conventional Design. Angle orthod 2004;75: 75-85.
48. Kusy RP., Whitley JQ. Resistance to sliding of orthodontic appliances in the dry and wet states: Influence of archwire alloy, interbracket distance, and bracket engagement. J Biomed Mater Res 2000;52: 797-811.
49. Pratten D. et al. Frictional resistance of ceramic and stainless steel orthodontic brackets. Am J Orthod Dentofac Orthop 1990;98:398-403.
50. Tselepis M., Brockhurst P., West VC. The dynamic frictional resistance between orthodontic brackets and arch wires. Am J Orthod Dentofac Orthop 1994;106: 131-138.
51. Tonner R., Waters N. The characteristics of super-elastic Ni-Ti wires in three-point bending. Part I: The effect of temperature. Euro J Orthod 1994;16: 409-19.