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Minerva Stomatologica 2017 June;66(3):107-14

DOI: 10.23736/S0026-4970.17.03984-X


language: English

Comparative assessment of different recycling methods of orthodontic brackets for clinical use

Ayla M., de OLIVEIRA CORREIA 1, Felipe, de SOUZA MATOS 1, Renata PILLI JÓIAS 2, Sigmar, de MELLO RODE 2, Paulo F. CESAR 3, Luiz R. PARANHOS 4

1 Postgraduate Program in Restorative Dentistry, Institute of Science and Technology, São Paulo State University, São José dos Campos, Brazil; 2 Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University, São José dos Campos, Brazil; 3 Department of Biomaterials and Oral Biology, University of São Paulo, São Paulo, Brazil; 4 Department of Dentistry, Federal University of Sergipe, Lagarto, Brazil


BACKGROUND: This study aimed to assess bond strength of the resin/bracket interface, under in-vitro shear stress, of metal brackets recycled by different clinical protocols.
METHODS: Sixty stainless steel orthodontic brackets were bonded on acrylic resin. The Transbond XT™ resin was applied at the base of the bracket aided by a matrix, obtaining 1 mm of thickness, and photoactivated with a LED device (40 s; 500 mW/cm2). Samples were randomly divided into four groups (N.=15) according to the reconditioning/recycling protocol: aluminum oxide (AO) 90 µm; hydrofluoric acid 60 s (HA60); hydrofluoric acid 120 s (HA120); hydrofluoric acid 60 s + silane (HA60S). After recycling, the resin was applied at the base of the bracket for shear testing in a universal testing machine (0.5 mm/min). After reconditioning/recycling, the surfaces were analyzed by Scanning Electron Microscopy. Data obtained after the shear test were subjected to ANOVA and Tukey’s test (P<0.05).
RESULTS: The AO group presented higher values of shear bond strength compared to the other reconditioning/recycling protocols (P<0.05). The HA120 and HA60S groups presented statistically similar results, but HA120 presented strength below the recommended limit.
CONCLUSIONS: The recycling technique by aluminum oxide sandblasting was more effective for reconditioning orthodontic brackets when compared to the other protocols. The reconditioning technique with 10% hydrofluoric acid followed by the application of silane bonding agent may be used as an alternative protocol.

KEY WORDS: Orthodontic brackets - Dental materials - Aluminum oxide - Silanes

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