Comparative study of friction between metallic and conventional interactive self-ligating brackets in different alignment conditions

original article Comparative study of friction between metallic and conventional interactive self-ligating brackets in different alignment conditions Sérgio Ricardo Jakob1, Davison Matheus2, Maria Cristina Jimenez-Pellegrin3, Cecília Pedroso Turssi4, Flávia Lucisano Botelho do Amaral4 DOI: http://dx.doi.org/10.1590/2176-9451.19.3.082-089.oar Objective: The aim of this study was to compare the friction between three bracket models: conventional stainless steel (Ovation, Dentsply GAC), self-ligating ceramic (In-Ovation, Denstply GAC) and self-ligating stainless steel brackets (In-Ovation R, Dentsply GAC). Methods: Five brackets were used for each model. They were bonded to an aluminum prototype that allowed the simulation of four misalignment situations (n = 10). Three of these situations occurred at the initial phase (in which a 0.016in nickel-titanium wire was used): 1. horizontal; 2. vertical; and 3. simultaneous horizontal/vertical. One of the situations occurred at the final treatment phase: 4. no misalignment (in which a 0.019 x 0.025-inch stainless steel rectangular wire was used). The wires slipped through the brackets and friction was measured by a Universal Testing Machine. Results: Analysis of variance followed by Tukey’s Test for multiple comparisons (α = 0.05) were applied to assess the results. Significant interaction (p < 0.01) among groups was found. For the tests that simulated initial alignment, Ovation® bracket produced the highest friction. The two self-ligating models resulted in lower and similar values, except for the horizontal situation, in which In-Ovation C® showed lower friction, which was similar to the In-Ovation R® metallic model. For the no misalignment situation, the same results were observed. Conclusion: The self-ligating system was superior to the conventional one due to producing less friction. With regard to the material used for manufacturing the brackets, the In-Ovation C® ceramic model showed less friction than the metallic ones. Keywords: Orthodontic brackets. Friction. Esthetics. Objetivo: o objetivo desse trabalho in vitro foi comparar o atrito entre três modelos de braquetes: Ovation (convencional, aço inoxidável); In-Ovation C (autoligável, cerâmico) e In-Ovation R (autoligável, aço inoxidável), todos do mesmo fabricante (Dentsply GAC). Métodos: para cada modelo, foram utilizados cinco braquetes, colados a um protótipo de alumínio, que permitiu a simulação de quatro situações (n = 10), sendo uma delas sem desalinhamento (com utilização de fio retangular de aço inoxidável, com espessuras de 0,019" x 0,025") e outras três com desalinhamento, sendo um horizontal, um vertical e outro simultaneamente combinando ambos (com utilização de fio de níquel-titânio com espessura de 0,016"). O atrito foi mensurado por uma máquina universal de ensaios. Resultados: os resultados obtidos foram submetidos ao teste de Análise de Variância, complementado pelo teste de comparações múltiplas de Tukey (α = 0,05). Foi observada interação significativa entre os grupos (p < 0,01). Para os ensaios que simularam a fase inicial de alinhamento, realizada com fios de NiTi, o braquete Ovation foi o que produziu o maior atrito, e os dois modelos autoligáveis produziram resultados menores e semelhantes, exceto para o ensaio de desalinhamento horizontal, onde o In-Ovation C apresentou atrito menor do que o similar metálico In-Ovation R. Na fase em que o fechamento de espaço foi simulado, os mesmos resultados foram observados. Conclusão: pode-se concluir que o sistema de autoligável mostrou-se superior ao convencional, com elastômeros, por produzir menor atrito. Quanto ao material utilizado na confecção dos braquetes, o modelo cerâmico In-Ovation C apresentou menor atrito que os metálicos. Palavras-chave: Braquetes ortodônticos. Atrito. Estética. How to cite this article: Jakob SR, Matheus D, Jimenez-Pellegrin MC, Turssi CP, Amaral FLB. Comparative study of friction between metallic and conventional interactive self-ligating brackets in different alignment conditions. Dental Press J Orthod. 2014 May-June;19(3):82-9. DOI: http://dx.doi.org/10.1590/21769451.19.3.082-089.oar MSc in Orthodontics, Camilo Castelo Branco University, UNICASTELO. 2 MSc in Orthodontics, São Leopoldo Mandic College of Dentistry. 3 Professor, São Leopoldo Mandic College of Dentistry. 4 Assistant Professor, Department of Operative Dentistry, São Leopoldo Mandic College of Dentistry. 1 » The authors report no commercial, proprietary or financial interest in the products or companies described in this article. Contact address: Flávia Lucisano Botelho do Amaral Instituto e Centro de Pesquisas Odontológicas São Leopoldo Mandic Rua José Rocha Junqueira, 13 – Swift – Campinas/SP — Brazil CEP: 13045-755 – Email: Submitted: February 14, 2013 - Revised and accepted: August 16, 2013 © 2014 Dental Press Journal of Orthodontics 82 Dental Press J Orthod. 2014 May-June;19(3):82-9 original article Jakob SR, Matheus D, Jimenez-Pellegrin MC, Turssi CP, Amaral FLB wires for sliding movements is considered relevant as they may exert some pressure in the ligation system, a factor that may increase friction.15 Therefore, additional research studies are necessary to further investigate not only friction of the ligation systems, but also the composition of orthodontic accessories. introduction Over the last few years, one of the most widely studied fields in orthodontic research has been the performance of self-ligating brackets due to its alleged advantages over conventional ligation systems.1-4 In addition to retaining the wire inside the bracket slot, the ligation system works in symbiosis with the wire and increases the effectiveness of dental movement.5 Friction is represented by the formula: friction = μ x F, in which μ represents the coefficient of friction and F is the perpendicular force when surfaces are in contact. According to Kusy and Whitley,6 in order to move the tooth along the arch, the applied force needs to overcome static friction at approximately 50% of the total force applied to the tooth. Thus, high levels of force are needed in situations of high friction. Several articles have shown a significant reduction in friction when self-ligating brackets are used.7-14 Another factor directly related to friction at the bracket-wire interface is the material with which the orthodontic accessory is fabricated, since surface roughness directly interferes in the amount of friction produced. Therefore, when choosing the best bracket for dental movement, particularly in mechanics when sliding is a preponderant factor, it is imperative to comparatively assess friction generated by metallic, esthetic, and hybrid brackets (esthetic brackets with metal slots). In addition, misalignment (horizontal, vertical, horizontal/vertical) or complete alignment may have some type of influence on friction. In horizontal misalignment, friction caused by the ligation system is of primary importance, beca (...truncated)