Torque expression capacity of 0.018 and 0.022 bracket slots by changing archwire material and cross section

Angela Arreghini, Luca Lombardo, Francesco Mollica, Giuseppe Siciliani, Angela Arreghini, Luca Lombardo, Francesco Mollica, Giuseppe Siciliani

Abstract

Background: The aim of this study is to calculate and compare the play and torque expression of 0.018 and 0.022 bracket slots when engaged with archwires of different size, cross section and material.

Methods: Eight orthodontic brackets, two of slot height 0.018 and six of slot height 0.022, from different manufacturers, were measured and fixed to a vertical support. Twenty-four archwires of differing size, cross section and material were selected, measured and tested in each bracket of compatible slot width. Compression testing by Instron dynamometer and geometric calculations enabled us to determine the play angle of each bracket/archwire combination, and the angle at which a clinically efficacious force couple, sufficient for dental movement, is exerted.

Results: All bracket/archwire combinations considered were found to have play angles far above the ideal. This is ascribable to the slots being oversized with respect to the manufacturers' claims. Likewise, some archwires were found to be oversized, while others undersized.When the same archwire was tested with brackets from different manufacturers, the play and torque expression differed, despite the same nominal dimensions of the slots. When the same bracket was tested with the same size archwires, their construction material was found to influence the torque expression, due to the difference in elastic modulus, but not the wire/slot play.

Conclusions: The dimensional precision of orthodontic brackets and archwires and the rigidity of the latter have a profound influence on the torque expression of pre-angled appliances.

Figures

Figure 1
Figure 1
Nexus bracket photographed under electron microscope.
Figure 2
Figure 2
Torque testing using an Instron 4467 dynamometer.
Figure 3
Figure 3
Measuring the distance between bracket slot and top of stand.
Figure 4
Figure 4
Torquing key with archwire engaged.
Figure 5
Figure 5
Torque testing.
Figure 6
Figure 6
Schematic of torque testing.
Figure 7
Figure 7
Load/deflection curve, steel archwire.
Figure 8
Figure 8
Load/deflection curve, NiTi archwire.

References

    1. Meling T, Ødegaard J. The effect of cross sectional dimensional variations of square and rectangular chrome-cobalt archwires in torsion. Angle Orthod. 1998;68(3):239–48.
    1. Burstone CJ. The segmented arch approach to space closure. Am J Orthod. 1982;82:361–78. doi: 10.1016/0002-9416(82)90185-3.
    1. Wahl N. Orthodontics in 3 millennia. Chapter 2: entering the modern era. Am J Orthod Dentofacial Orthop. 2005;127(4):510–5. doi: 10.1016/j.ajodo.2005.01.002.
    1. Wahl N. Orthodontics in 3 millennia. Chapter 16: late 20th-century fixed appliances. Am J Orthod Dentofacial Orthop. 2008;134(6):827–30. doi: 10.1016/j.ajodo.2008.04.016.
    1. Rinchuse DJ, Rinchuse DJ, Kapur-Wadhwab R. Orthodontic appliance design. Am J Orthod Dentofacial Orthop. 2007;131(1):76–82. doi: 10.1016/j.ajodo.2005.04.039.
    1. Kusy RP. A review of contemporary archwires: their proprieties and characteristics. Angle Orthod. 1997;67(3):197–208.
    1. Kusy RP, Whitley JQ. Thermal and mechanical characteristics of stainless steel, titanium-molybdenum, and nickel-titanium archwires. Am J Orthod Dentofacial Orthop. 2007;131:229–37. doi: 10.1016/j.ajodo.2005.05.054.
    1. Johnson E. Relative stiffness of beta titanium archwires. Angle Orthod. 2003;73:259–69.
    1. Gurgel JA, Pinzan-Vercelino CRM, Powers JM. Mechanical properties of beta-titanium wires. Angle Orthod. 2011;81:478–83. doi: 10.2319/070510-379.1.
    1. Sifakakis I, Pandis N, Makou M, Eliades T, Katsaros C, Bourauel C. Torque expression of 0.018 and 0.022 inch conventional brackets. Eur J Orthod. 2013;35(5):610–4. doi: 10.1093/ejo/cjs041.
    1. Detterline DA, Isikbay SC, Brizendine EJ, Kula KS. Clinical outcomes of 0.018-inch and 0.022-inch bracket slot using the ABO objective grading system. Angle Orthod. 2010;80(3):528–32. doi: 10.2319/060309-315.1.
    1. Meling TR, Ødegaard J. The effect of second-order couple on the application of torque. Am J Orthod Dentofacial Orthop. 1998;113:256–62. doi: 10.1016/S0889-5406(98)70294-X.
    1. Meling TR, Ødegaard J. On the variability of cross-sectional dimensions and torsional properties of rectangular nickel-titanium arch wires. Am J Orthod Dentofacial Orthop. 1998;113:546–57. doi: 10.1016/S0889-5406(98)70266-5.
    1. Cash AC, Good SA, Curtis RV, McDonald F. An evaluation of slot size in orthodontic brackets—are standards as expected? Angle Orthod. 2004;74:450–3.
    1. Demling A, Dittmer MP, Schwestka-Polly R. Comparative analysis of slot dimension in lingual bracket systems. Head Face Med. 2009;5:27. doi: 10.1186/1746-160X-5-27.
    1. Rucker BK, Kusy RP. Elastic flexural properties of multistranded stainless steel versus conventional nickel titanium archwires. Angle Orthod. 2002;72:302–9.
    1. Huang Y, Keilig L, Rahimi A, Reimann S, Eliades T, Jager A, Bourauel C. Numeric modeling of torque capabilities of self-ligating and conventional brackets. Am J Orthod Dentofacial Orthop. 2009;136:638–43. doi: 10.1016/j.ajodo.2009.04.018.
    1. Badawi HM, Toogood RW, Carey JPR, Heo G, Major PW. Torque expression of self-ligating brackets. Am J Orthod Dentofacial Orthop. 2008;133:721–8. doi: 10.1016/j.ajodo.2006.01.051.
    1. Flores DA, Choi LK, Caruso JM, Tomlinson JL, Scott GE, Jeiroudi MT. Deformation of metal brackets: a comparative study. Angle Orthod. 1994;64(4):283–90.
    1. Flores DA, Caruso JM, Scott GE, Jeiroudi MT. The fracture strength of ceramic brackets: a comparative study. Angle Orthod. 1990;60(4):269–76.
    1. Archambault A, Lacoursierea R, Badawi H, Major PW, Carey J, Flores-Mir C. Torque expression in stainless steel orthodontic brackets. Angle Orthod. 2010;80:201–10. doi: 10.2319/080508-352.1.
    1. Kapur R, Sinh PK, Nanda RS. Comparison of load transmission and bracket deformation between titanium and stainless steel brackets. Am J Orthod Dentofacial Orthop. 1999;116:275–8. doi: 10.1016/S0889-5406(99)70238-6.
    1. Major TW, Carey JP, Nobes DS, Heo G, Major PW. Deformation and warping of the bracket slot in select self-ligating orthodontic brackets due to an applied third order torque. J Orthod. 2012;39(1):25–33. doi: 10.1179/14653121226797.
    1. Major TW, Carey JP, Nobes DS, Heo G, Melenka GW, Major PW. An investigation into the mechanical characteristics of select self-ligated brackets at a series of clinically relevant maximum torquing angles: loading and unloading curves and bracket deformation. Eur J Orthod. 2013;35(6):719–29. doi: 10.1093/ejo/cjr076.
    1. Kang B, Baek S, Mah J, Yang W. Three-dimensional relationship between the critical contact angle and the torque angle. Am J Orthod Dentofacial Orthop. 2003;123:64–73. doi: 10.1067/mod.2003.55.
    1. Lacoursiere RA, Nobes DS, Homeniuk DL, Carey JP, Badawi HH, Major PW. Measurement of orthodontic bracket tie wing elastic and plastic deformation by arch wire torque expression utilizing an optical image correlation technique. J Dent Biomech. 2010;2010:Epub 2009 Dec 13.

Source: PubMed

Sponsors en medewerkers

Medische omstandigheden

Geneesmiddelinterventies

3
Abonneren