Luís Antônio Di Guida1, Paula Benetti1, Pedro Henrique Corazza1, Alvaro Della Bona2. 1. Post-graduation Program in Dentistry, Dental School, University of Passo Fundo, Campus I, BR 285, Passo Fundo, RS, 99052-900, Brazil. 2. Post-graduation Program in Dentistry, Dental School, University of Passo Fundo, Campus I, BR 285, Passo Fundo, RS, 99052-900, Brazil. dbona@upf.br.
Abstract
OBJECTIVES: To evaluate the critical bond strength (σ) of ceramic and metal brackets to a lithium disilicate-based glass-ceramic. MATERIALS AND METHODS: Two hundred and forty ceramic specimens (IPS e-max CAD) were randomly distributed in 12 experimental groups (n = 20). Two ceramic brackets (monocrystalline, BCm; and polycrystalline, BCp) and a metal bracket (BM) were bonded to glass-ceramic specimens after one of the following surface treatments: HF-hydrofluoric acid applied for 60 s; S-silane applied for 3 min; HFS-HF followed by S; and MDP-application of an adhesive containing a phosphate monomer (MDP). All brackets were bonded to the treated glass-ceramic using a resin cement, stored in 37 °C water for 48 h before shear bond strength testing. Optical (OM) and scanning electron (SEM) microscopies were used for fractographic analysis. Data was statistically analyzed using Kruskal-Wallis and Student-Newman-Keuls (α = 0.05). RESULTS: BCm bonded to glass-ceramic treated with either HFS or HF showed the highest median σ values, respectively, 10.5 MPa and 8.5 MPa. In contrast, the BCp bonded to glass-ceramic treated with MDP showed the lowest median σ value (0.8 MPa), which was not statistically different from other MDP-treated groups. CONCLUSIONS: The failure mode was governed by the glass-ceramic surface treatment, not by the bracket type. Quantitative (σ values) and qualitative (fracture mode) data suggested a minimum of 5 MPa for brackets bonded to glass-ceramic, which is the lower critical limit bond strength for a comprehensive orthodontic treatment. CLINICAL RELEVANCE: Bonding brackets to glass-ceramic requires micromechanical retention.
RCT Entities:
OBJECTIVES: To evaluate the critical bond strength (σ) of ceramic and metal brackets to a lithium disilicate-based glass-ceramic. MATERIALS AND METHODS: Two hundred and forty ceramic specimens (IPS e-max CAD) were randomly distributed in 12 experimental groups (n = 20). Two ceramic brackets (monocrystalline, BCm; and polycrystalline, BCp) and a metal bracket (BM) were bonded to glass-ceramic specimens after one of the following surface treatments: HF-hydrofluoric acid applied for 60 s; S-silane applied for 3 min; HFS-HF followed by S; and MDP-application of an adhesive containing a phosphate monomer (MDP). All brackets were bonded to the treated glass-ceramic using a resin cement, stored in 37 °C water for 48 h before shear bond strength testing. Optical (OM) and scanning electron (SEM) microscopies were used for fractographic analysis. Data was statistically analyzed using Kruskal-Wallis and Student-Newman-Keuls (α = 0.05). RESULTS:BCm bonded to glass-ceramic treated with either HFS or HF showed the highest median σ values, respectively, 10.5 MPa and 8.5 MPa. In contrast, the BCp bonded to glass-ceramic treated with MDP showed the lowest median σ value (0.8 MPa), which was not statistically different from other MDP-treated groups. CONCLUSIONS: The failure mode was governed by the glass-ceramic surface treatment, not by the bracket type. Quantitative (σ values) and qualitative (fracture mode) data suggested a minimum of 5 MPa for brackets bonded to glass-ceramic, which is the lower critical limit bond strength for a comprehensive orthodontic treatment. CLINICAL RELEVANCE: Bonding brackets to glass-ceramic requires micromechanical retention.
Entities:
Keywords:
Adhesion; Ceramics; Material strength; Orthodontic brackets
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