Does self-ligating brackets type influence the hysteresis, activation and deactivation forces of superelastic NiTi archwires?

original article Does self-ligating brackets type influence the hysteresis, activation and deactivation forces of superelastic NiTi archwires? José Rino Neto1, Gilberto Vilanova Queiroz2, João Batista de Paiva3, Rafael Yagüe Ballester4 Objective: To compare hysteresis, activation and deactivation forces produced by first-order deformation of Contour 0.014-in NiTi wire (Aditek, Brazil) in four brands of self-ligating brackets: Damon MX, Easy Clip, Smart Clip and InOvation. Methods: Activation and deactivation forces were measured in an Instron universal tensile machine at 3 mm/ minute speed to a total displacement of 4 mm. Tests were repeated eight times for each bracket/wire combination. Statistical analysis comprised ANOVA and Tukey’s multiple comparisons test. Results: Using a 4-mm deformation, mean activation forces increased in the following order: Damon = 222 gf, Easy Clip = 228 gf, In-Ovation = 240 gf and Smart Clip = 306 gf. The same order was observed for mean hysteresis values, i.e., 128 gf, 140 gf, 150 gf and 206 gf, respectively. The respective values of deactivation forces for the Damon, Easy Clip, In-Ovation and Smart Clip brackets were 94 gf, 88 gf, 90 gf and 100 gf. Conclusions: Brackets with higher activation forces were accompanied by higher hysteresis values, which resulted in clinically similar deactivation forces, regardless of the type of self-ligating brackets used. Keywords: Corrective orthodontics. Orthodontic brackets. Orthodontic wires. Objetivo: comparar as forças de ativação, desativação e histerese produzidas por deformação de primeira ordem do fio superelástico Contour NiTi 0,014” (Aditek®) em quatro modelos de braquetes autoligáveis: Damon MX, Easy Clip, Smart Clip e In-Ovation. Métodos: as forças de ativação e desativação foram medidas em máquina universal de tração Instron com velocidade de 3mm/minuto e deslocamento de 4mm. Em cada combinação braquete/fio foram executadas oito repetições. A análise estatística empregou ANOVA e o Teste de Comparações Múltiplas de Tukey. Resultados: com 4mm de deformação, as forças médias de ativação foram, em ordem crescente, Damon = 222gf, Easy Clip = 228gf, In-Ovation = 240gf e Smart-Clip = 306gf; a mesma ordem foi observada nas histereses médias, cujos valores foram, respectivamente, 128gf, 140gf, 150gf e 206gf; os valores das forças de desativação foram, respectivamente, 94gf, 88gf, 90gf e 100gf. Conclusão: os braquetes com maiores valores nas forças de ativação foram acompanhados por maiores valores na histerese, o que resultou em forças de desativação clinicamente semelhantes, independentemente do tipo de braquete autoligável utilizado. Palavras-chave: Ortodontia corretiva. Fios ortodônticos. Aparelhos ortodônticos. How to cite this article: Rino Neto J, Queiroz GV, Paiva JB, Ballester RY. Does self-ligating brackets type influence the hysteresis, activation and deactivation forces of superelastic NiTi archwires? Dental Press J Orthod. 2013 JanFeb;18(1):81-5. Associate Professor, Department of Orthodontics, School of Dentistry, University of São Paulo (FOUSP). 2 MSc and PhD in Orthodontics, FOUSP. 3 Full Professor, Department of Orthodontics, FOUSP. 4 Full Professor, Department of Dental Materials, FOUSP. 1 Submitted: January 16, 2010 - Revised and accepted: December 29, 2010 » The author reports no commercial, proprietary or financial interest in the products or companies described in this article. Contact address: Gilberto Vilanova Queiroz Via Piacenza, 144 – Jd. Paradiso – CEP: 13.331-545 – Indaiatuba/SP – Brazil E-mail: © 2013 Dental Press Journal of Orthodontics 81 Dental Press J Orthod. 2013 Jan-Feb;18(1):81-5 original article Does self-ligating brackets type influence the hysteresis, activation and deactivation forces of superelastic NiTi archwires? The testing device consisted of four cylinders that could be moved vertically and two guiding slots with internal dimensions of 0.022 x 0.028-in positioned at the ends of the bracket area (Fig 1). In order to achieve parallelism and leveling between the bracket slots bonding was performed by simultaneously inserting a standard 0.022-in ruler into both the guiding slots and the bracket slots. Direct bonding of the brackets was performed individually and followed this sequence: Insertion of standard 0.022-in ruler into the guiding slots, application of cyanoacrylate (Superbonder, Henckel / Brazil) to the bracket base and positioning at the center of the cylinder, sliding of the cylinder until the bottom of the slot fit the 0.022-in standard ruler in its entire mesiodistal extension, determining the final bonding position (Fig 2). Direct bonding of the brackets with cyanoacrylate showed sufficient strength to stabilize the brackets during the mechanical tests, even in specimens without full contact between bonding surface and bracket base (Fig 2). The distance from bracket center to bracket center was 7.5 mm. To obtain the forces produced by the 0.014-in SE NiTi archwire in the different types of self-ligating brackets a support was developed whose upper portion was inserted into the Instron tensile machine and bottom portion displayed a surface where the canine would be bonded. introduction Activation force is defined as the force required to deform an archwire when it is inserted into a misaligned bracket slot,8 whereas deactivation force is the force applied by the archwire on a misaligned bracket when it is reverting to its original shape. Friction in the contact region between wire and bracket is one of the factors affecting the magnitude of both activation and deactivation forces. The higher the friction, the greater the force required by an archwire to slide in the slots of brackets placed on anchorage teeth.9,11 Friction in orthodontic sliding mechanics can be divided into two key components: Classic friction and binding. Classic friction is caused by the elastomeric ligatures compressing the archwire against the bottom of the bracket slot,9 which is controlled using self-ligating brackets, i.e., brackets that do not require the use of elastomeric ligatures given their own unique ligation devices.1,2,3,5 Binding, in turn, is a type of friction caused by archwire deformation (strain), with intensity depending on the force with which the archwire is pressed against the slots of the anchorage brackets.9,11 The magnitude of binding produced by first order deformation in Contour NiTi 0.014-in wire (Aditek) varies according to the type of self-ligating brackets used.14 Given that wire activation and deactivation forces are influenced by friction occurring between orthodontic wire and bracket9,11 it is important to evaluate if different self-ligating brackets affect the forces produced by wire deformation in superelastic NiTi wires. The aim of this study was to compare the forces of activation, deactivation and hysteresis produced by the deformation of Contour 0.014-in NiTi wire in four different self-ligating brackets, i.e., Damon, (...truncated)