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A Journal on Dentistry and Maxillofacial Surgery
Minerva Stomatologica 2017 Mar 01
Copyright © 2017 EDIZIONI MINERVA MEDICA
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, SP, Brazil; 2 Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University, São José dos Campos, SP, Brazil; 3 Department of Biomaterials and Oral Biology, University of São Paulo, São Paulo, SP, Brazil;4 Department of Dentistry, Federal University of Sergipe, Lagarto, SE, 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 XTTM resin was applied at the base of the bracket aided by a matrix, obtaining 1 mm of thickness, and photoactivated with a LED device (40s; 500 mW/cm2). Samples were randomly divided into four groups (n=15) according to the reconditioning/recycling protocol: AO - aluminum oxide / 90 μm; HA60 - hydrofluoric acid 60s; HA120 - hydrofluoric acid 120s; HA60S - hydrofluoric acid 60s + silane. 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: Orthodontics - Shear bond strength - Aluminum oxide