Fricção em braquetes gerada por fios de aço inoxidável, superelásticos com IonGuard e sem IonGuard

Abstract

OBJETIVO: o objetivo deste estudo foi verificar a fricção no braquete (Roth, Composite, 10.17.005, 3,2mm, largura 0,022" x 0,030", Torque -2° e angulação +13°, Morelli®, Brasil), utilizando fios ortodônticos retangulares de 0,019" x 0,025" de aço inoxidável (Morelli®, Brasil) e de níquel-titânio superelásticos Bioforce com IonGuard e sem IonGuard (Bioforce, GAC®, EUA). MÉTODOS: foram utilizados 24 conjuntos braquetes/segmento de fio, divididos em 3 grupos de acordo com o fio. Cada conjunto braquete/segmento de fio foi testado 3 vezes e obtida uma média. Os ensaios foram realizados em máquina universal de ensaios EMIC DL2000®. Os dados foram submetidos à Análise de Variância com significância de 95%. RESULTADOS: o fio retangular Bioforce com IonGuard apresentou fricção significativamente menor que o Bioforce sem IonGuard, porém sem diferença do fio de aço inoxidável. Entretanto, o coeficiente de variação dos fios Bioforce com e sem IonGuard foi menor que o do fio de aço inoxidável. CONCLUSÃO: os fios retangulares de 0,019" x 0,025" Bioforce com IonGuard apresentam menor fricção que o fio Bioforce sem IonGuard, sem diferença para o fio de aço inoxidável.

Evaluation of friction on self-ligating and conventional brackets associated with different types of archwires submitted to sliding mechanics

“…This experimental in vitro study was conducted with 30 sets of plate/bracket/archwire segments that were divided into three Groups according to the brackets used, i.e., conventional metal (Ref. 10 The test specimens were made up of a rectangular acrylic plate 3,5,10,14,25 , measuring 8.5 cm long, 4 cm wide and 0.5 cm thick with metal brackets (conventional), slot 0.022 x 0.028 inches, from the maxillary right 2nd premolar to the maxillary right central incisor 5,14 , combined with a segment of rectangular section 0.019 x 0.025 inches of copper nickel titanium and stainless steel (Morelli, Sorocaba, SP, Brazil) 3,5,25 , as shown in Figure 1. The position of each bracket was demarcated on the plate and abraded with a spherical bur at low speed, cleaned with gauze imbibed in 70% alcohol, and dried with absorbent paper towels to prevent the presence of substances or dirt that could compromise the results obtained, thereby increasing the relationship of brackets and preventing these from debonding from the plate during the tests 11,13 .…”

“…This was done to obtain the maximum level of standardization among the groups, to prevent any poorly positioned bracket from affecting the reliability of the results 11,14 . After the brackets were fixed, the rectangular archwire segments of copper nickel titanium and stainless steel, measuring 0.019 x 0.025 inches and 20 cm long were positioned 3,10,23,24 .…”

“…A high frictional coefficient may reduce the force used for orthodontic movement by half, diminishing the speed of tooth movement and making it difficult to control anchorage. The frictional force should be as low as possible with the goal of achieving greater mechanical efficiency; that is, the force applied must be sufficient to break the static friction and enable tooth movement 2,6,9,[10][11][12][13] .…”

“…The frictional force may vary according to the materials used, and whether the environment is wet or dry, type of brackets, archwires and ligations. Self-ligating brackets may be divided into active and passive types; the active types have a spring clip that invades the bracket slot putting pressure on the archwire, while in the passive system, the clip does not invade the slot, it only covers the slot without putting pressure on the archwire [1][2][3][4][5]7,10,12,[14][15][16][17][18][19] .…”

“…However, the technological evolution has led to new archwires being used, among them the nickel titanium type with the addition of copper (CuNiTi) 17,21 . The incorporation of copper has resulted in these archwires having more defined thermoactive properties than the superelastic NiTi archwires, therefore, they exert more homogeneous forces throughout the arch, providing faster, more effective movement, in an optimal system of forces, with greater control of tooth movement; they may be used in different orthodontic treatment protocols, as they achieve more biologically compatible results by releasing more physiological force and shortening the time of treatment 2,4,10,[21][22][23] .…”