Revista de Odontologia da UNESP
https://revodontolunesp.com.br/article/doi/10.1590/1807-2577.04819
Revista de Odontologia da UNESP
Original Article

Fracture strength of monocrystalline and polycrystalline ceramic brackets during archwire torque

Resistencia à fratura de braquetes cerâmicos

Társio Caleb Bernardon KIELING; Lourenço CORRER-SOBRINHO; Ana Paula Terossi de GODOI; Carolina Carmo de MENEZES; Giovana Cherubini VENEZIAN; Ana Rosa COSTA

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Abstract

Abstract: Introduction: In recent years, there has been an increasing demand for esthetic treatments, especially among orthodontic patients.

Objective: This study determined the fracture strength of monocrystalline and polycrystalline ceramic brackets of different manufacturers during archwire torque.

Material and method: Sixty ceramic brackets (Roth, right upper central incisors, 0.022 x 0.028-inch slot) were allocated into two groups (30 specimens per group) according to the type of ceramics: monocrystalline and polycrystalline. Subsequently, the groups were divided into three subgroups (n = 10) according to the manufacturer: Orthometric, Eurodonto and Ortho Technology. Sixty PVC cylinders were filled with chemically activated acrylic resin (CAAR), the brackets were fixed with CAAR onto the cylinder surface and the excess material was used to partially cover the base of the bracket. After 24h, the U-shaped wire base (0.019 x 0.025 inches; 6 mm height and width) was inserted into the bracket slot and fixed thereon with a stainless-steel wire. Vertical folds were made at the ends of the “U” to support the universal test machine chisel. The fracture strength test was performed at a speed of 1.0 mm/min until fracture into a universal test machine (Instron). The data were recorded, transformed into g.mm and submitted to two-way ANOVA followed by Tukey’s post-hoc test (SAS Institute Inc., Cary, NC, USA, version 9.3) (α=5%).

Result: Monocrystalline brackets showed a higher fracture strength than polycrystalline brackets, regardless of the manufacturer (p<0.05). The highest fracture strength values were observed in Ortho Technology and Orthometric brackets, with no significant difference between them (p>0.05).

Conclusion: Monocrystalline ceramic brackets have a higher fracture strength than polycrystalline brackets, with significant manufacturer-dependent differences.

Keywords

Ceramic brackets, fracture strength, torsion, torque

Resumo

Resumo: Introdução: A demanda por tratamentos estéticos tem crescido nos últimos anos, sendo cada vez mais forte a preocupação com a estética por parte dos pacientes que buscam o tratamento ortodôntico.

Objetivo: Este estudo avaliou a resistência à fratura de bráquetes cerâmicos monocristalinos e policristalinos de diferentes fabricantes quando submetidos ao torque do fio.

Material e método: Sessenta bráquetes cerâmicos (Roth, incisivos centrais superiores direito, canaleta 0,022 x 0,028 polegadas) foram divididos em 2 grupos (30 espécimes por grupo) de acordo com o tipo da cerâmica: monocristalina e policristalina. Posteriomente estes grupos foram divididos em 3 sub-grupos (n=10) de acordo com o fabricante: Orthometric, Eurodonto e Ortho Technology. Segmentos de fio de aço inoxidável retangular (0,019 x 0,025 polegadas) foram dobrados em forma de “U”, sendo que a base do “U” foi inserida na canaleta do bráquete e fixado com fio de amarilho em aço inoxidável (0,008mm). Nas extremidades do “U” foram realizadas dobras verticais para servir de apoio para o cinzel da máquina de ensaio universal Instron. O ensaio de resistência à fratura foi realizado à velocidade de 1,0 mm/min até ocorrer a fratura. Os dados foram registrados, transformados em g.mm e submetidos à ANOVA dois fatores e ao teste de Tukey (SAS Institute Inc., Cary, NC, USA, version 9.3) (α=5%).

Resultado: Os bráquetes monocristalinos apresentaram maior resistência à fratura em relação aos policristalinos, independente do fabricante (p<0,05). Os maiores valores de resistência à fratura foram obtidos com os bráquetes da Ortho Technology e Orthometric, os quais não diferiram estatisticamente entre si (p>0,05).

Conclusão: Bráquetes monocristalinos possuem maior resistência à fratura em relação aos policristalinos com diferenças na resistência à fratura entre os diferentes fabricantes.
 

Palavras-chave

Bráquetes cerâmicos, resistência à fratura, torção, torque

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