Korean J Orthod.  2015 Jul;45(4):198-208. 10.4041/kjod.2015.45.4.198.

Effect of activation and preactivation on the mechanical behavior and neutral position of stainless steel and beta-titanium T-loops

Affiliations
  • 1Department of Orthodontics, Faculty of Dental Medicine, University of Porto, Porto, Portugal. scastro@fmd.up.pt
  • 2Department of Mechanical Engineering, University of Aveiro, Aveiro, Portugal.
  • 3Department of Production and Systems Engineering, School of Engineering, University of Minho, Braga, Portugal.

Abstract


OBJECTIVE
To quantify, for each activation, the effect of preactivations of differing distribution and intensity on the neutral position of T-loops (7-mm height), specifically the horizontal force, moment to force (M/F) ratio, and load to deflection ratio.
METHODS
A total 100 loops measuring 0.017 x 0.025 inches in cross-section were divided into two groups (n = 50 each) according to composition, either stainless steel or beta-titanium. The two groups were further divided into five subgroups, 10 loops each, corresponding to the five preactivations tested: preactivations with occlusal distribution (0degrees, 20degrees, and 40degrees), gingival distribution (20degrees), and occlusal-gingival distribution (40degrees). The loops were subjected to a total activation of 6-mm with 0.5-mm iterations. Statistical analysis was performed using comprised ANOVA and Bonferoni multiple comparison tests, with a significance level of 5%.
RESULTS
The location and intensity of preactivation influenced the force intensity. For the M/F ratio, the highest value achieved without preactivation was lower than the height of the loop. Without preactivation, the M/F ratio increased with activation, while the opposite effect was observed with preactivation. The increase in the M/F ratio was greater when the preactivation distribution was partially or fully gingival.
CONCLUSIONS
Depending on the preactivation distribution, displacement of uprights is higher or lower than the activation, which is a factor to consider in clinical practice.

Keyword

Neutral position; Preactivation; T-loop

MeSH Terms

Analysis of Variance
Stainless Steel*
Stainless Steel

Figure

  • Figure 1 A, Schematic representation of the T-loop and respective dimensions (mm). The front end of the loop is indicated by alpha (α), while beta (β) indicates the rear end of the loop. B, Test board: The OrthoMeasure Moment/Force/digital comparator (Orthomeasurments®; Division of Young Research & Development, Avon, CT, USA) was used to quantify the horizontal forces.

  • Figure 2 Schematic representation of the T-loop activation for each group. A, Numerical identification of the four bend locations; B, schematic representation of the T-loop with 20° preactivation (10° insertion in bends 1 and 2); C, 40° preactivation (20° insertion in bends 1 and 2); D, 20°° preactivation (10° insertion in bends 3 and 4) ; E, 40°° preactivation (10° insertion in bends 1, 2, 3, and 4).

  • Figure 3 Photograph of the inserted loop.

  • Figure 4 Mean force values and 95% confidence intervals (CI) for activation and preactivation in each material (beta-titanium [TMA] and stainless steel [SS]).

  • Figure 5 Mean moment to force (M/F) ratio values and 95% confidence intervals (CI) according to activation and preactivation in each material (beta-titanium [TMA] and stainless steel [SS]).

  • Figure 6 Mean load to deflection (L/D) ratio values and 95% CI by activation according to preactivation values for each material (beta-titanium [TMA] and stainless steel [SS]).

  • Figure 7 Schematic representation of the T-loop generated by the LOOP computer program (dHAL Orthodontic Software®, Athens, Greece). A, 20° activation/Apply Moment (neutral position); B, 40° activation/Apply Moment (neutral position); C, 20°° activation/Apply Moment (neutral position); D, 40°° activation/Apply Moment (neutral position).


Reference

1. Weinstein S, Haack DC. Theoretical mechanics and practical orthodontics. Angle Orthod. 1959; 29:177–181.
2. Vaden JL, Dale JG, Klontz HA. Aparato arco de canto de Tweed-Merrifield: filosofia, diagnóstico y tratamiento. In : Restrepo GAU, editor. Ortodoncia principios generales y técnicas. 3rd ed. Buenos Aires: Editorial Médica Panamericana S.A;2003. p. 625–682.
3. Burstone CJ, Koenig HA. Optimizing anterior and canine retraction. Am J Orthod. 1976; 70:1–19. PMID: 1066042.
Article
4. Burstone CJ. The mechanics of the segmented arch techniques. Angle Orthod. 1966; 36:99–120. PMID: 5218678.
5. Smith RJ, Burstone CJ. Mechanics of tooth movement. Am J Orthod. 1984; 85:294–307. PMID: 6585147.
Article
6. Siatkowski RE. Force system analysis of V-bend sliding mechanics. J Clin Orthod. 1994; 28:539–546. PMID: 8617838.
7. Braun S, Garcia JL. The Gable bend revisited. Am J Orthod Dentofacial Orthop. 2002; 122:523–527. PMID: 12439481.
Article
8. Siatkowski RE. Continuous arch wire closing loop design, optimization, and verification. Part II. Am J Orthod Dentofacial Orthop. 1997; 112:487–495. PMID: 9387834.
Article
9. Techalertpaisarn P, Versluis A. Mechanical properties of Opus closing loops, L-loops, and T-loops investigated with finite element analysis. Am J Orthod Dentofacial Orthop. 2013; 143:675–683. PMID: 23631969.
Article
10. Chen J, Markham DL, Katona TR. Effects of T-loop geometry on its forces and moments. Angle Orthod. 2000; 70:48–51. PMID: 10730675.
11. Kuhlberg AJ, Burstone CJ. T-loop position and anchorage control. Am J Orthod Dentofacial Orthop. 1997; 112:12–18. PMID: 9228836.
Article
12. Maia LG, de Moraes Maia ML, da Costa Monini A, Vianna AP, Gandini LG Jr. Photoelastic analysis of forces generated by T-loop springs made with stainless steel or titanium-molybdenum alloy. Am J Orthod Dentofacial Orthop. 2011; 140:e123–e128. PMID: 21889060.
Article
13. Manhartsberger C, Morton JY, Burstone CJ. Space closure in adult patients using the segmented arch technique. Angle Orthod. 1989; 59:205–210. PMID: 2774296.
14. Marcotte MR. Mecânica em Ortodontia. In : Marcotte MA, editor. Biomecânica em ortodontia. 2nd ed. São Paulo: Livraria Santos Editora;2003. p. 1–21.
Article
15. Shimizu RH, Sakima T, Pinto AS, Shimizu IA. Desempenho biomecânico da alça "T", construída com fio de aço inoxidável, durante o fechamento de espaços no tratamento ortodôntico. R Dental Press Ortodon Ortop Facial. 2002; 7:49–61.
16. Souza RS, Pinto AS, Shimizu RH, Sakima MT, Gandini LG. Avaliação do sistema de forças gerado pela alça T de retração pré-ativada segundo o padrão UNESP-Araraquara. R Dental Press Ortodon Ortop Facial. 2003; 8:113–122.
17. Siatkowski RE. Continuous arch wire closing loop design, optimization, and verification. Part I. Am J Orthod Dentofacial Orthop. 1997; 112:393–402. PMID: 9345151.
Article
18. Thiesen G, Shimizu RH, do Valle CV, do Valle-Corotti KM, Pereira JR, Conti PC. Determination of the force systems produced by different configurations of tear drop orthodontic loops. Dental Press J Orthod. 2013; 18:19.e1–19.e18. PMID: 23916447.
Article
19. Braun S, Sjursen RC Jr, Legan HL. On the management of extraction sites. Am J Orthod Dentofacial Orthop. 1997; 112:645–655. PMID: 9423697.
Article
20. Halazonetis DJ. Understanding orthodontic loop preactivation. Am J Orthod Dentofacial Orthop. 1998; 113:237–241. PMID: 9484213.
Article
21. Viecilli RF. Self-corrective T-loop design for differential space closure. Am J Orthod Dentofacial Orthop. 2006; 129:48–53. PMID: 16443478.
Article
22. Rose D, Quick A, Swain M, Herbison P. Moment-to-force characteristics of preactivated nickel-titanium and titanium-molybdenum alloy symmetrical T-loops. Am J Orthod Dentofacial Orthop. 2009; 135:757–763. PMID: 19524835.
Article
23. Caldas SG, Martins RP, Galvão MR, Vieira CI, Martins LP. Force system evaluation of symmetrical beta-titanium T-loop springs preactivated by curvature and concentrated bends. Am J Orthod Dentofacial Orthop. 2011; 140:e53–e58. PMID: 21803234.
Article
24. Ferreira Mdo A, de Oliveira FT, Ignácio SA, Borges PC. Experimental force definition system for a new orthodontic retraction spring. Angle Orthod. 2005; 75:368–377. PMID: 15898375.
25. Burstone CJ, Koenig HA. Force systems from an ideal arch. Am J Orthod. 1974; 65:270–289. PMID: 4521361.
Article
26. Ingram SB Jr, Gipe DP, Smith RJ. Comparative range of orthodontic wires. Am J Orthod Dentofacial Orthop. 1986; 90:296–307. PMID: 3464191.
Article
27. Odegaard J, Meling T, Meling E. The effects of loops on the torsional stiffnesses of rectangular wires: an in vitro study. Am J Orthod Dentofacial Orthop. 1996; 109:496–505. PMID: 8638594.
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