RESUMEN
OBJECTIVES: The application of an electric field has been shown to positively influence the bonding of dentin bonding systems (DBS) by improving adhesive impregnation into dentin. However, the mechanism responsible for this phenomenon has not been completely elucidated. The aim of this study was to clarify the effects of pH, matrix ionic strength, and applied voltage on the migration of commonly used DBS monomers in a model matrix (agarose gel). METHODS: Some common monomers examined were bis-GMA (2,2-bis[4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane); HEMA (2-hydroxyethyl methacrylate); 2-MP (bis[2-(methacryloyloxy) ethyl] phosphate); TCDM [di(hydroxyethyl methacrylate) ester of 5-(2,5,-dioxo tetrahydrofurfuryl)-3-methyl-3-cyclohexenyl-1,2-dicarboxylic acid]; and TEGDMA (triethylene glycol dimethacrylate). Agarose gels poured into a horizontal 10-well electrophoretic cell were used to mimic the collagen fibrils of the dentin organic matrix. The role of pH, matrix ionic strength, and voltage on monomer migration was assayed by modifying the experimental conditions. RESULTS: Results of experiments performed at pH 3.1, 6.3, 8.5, and 12.3; at low, medium, and high ionic strength; and at 50 and 100 V clearly showed that DBA monomer migration toward both the anode and the cathode can be affected by each of these parameters. SIGNIFICANCE: Migration of acrylic monomers toward the anode or cathode can be achieved as desired by selective choice of pH, ionic strength, and applied voltage. Additional studies are needed to evaluate the synergistic effects of DBS monomer blends on migration in an electric field.
Asunto(s)
Recubrimientos Dentinarios/química , Electroforesis en Gel de Agar , Bisfenol A Glicidil Metacrilato/química , Ácidos Carboxílicos/química , Permeabilidad de la Dentina , Electricidad , Concentración de Iones de Hidrógeno , Ensayo de Materiales , Metacrilatos/química , Estructura Molecular , Concentración Osmolar , Polietilenglicoles/química , Ácidos Polimetacrílicos/químicaRESUMEN
OBJECTIVE: To evaluate the effects of surface moisture (wet or dry) and storage (24h or 3 months) on the microtensile bond strength (BS) of resin/dentin bonds mediated by two water/ethanol based adhesives Single Bond, 3M-ESPE, (SB) and Opti Bond Solo Plus, Kerr, (OB), and two acetone-based adhesives, One Step, Bisco, (OS) and Prime&Bond NT, Caulk/Dentsply, (PB). MATERIALS AND METHODS: Flat dentin surfaces were polished with 600-grit SiC paper, etched with 35% phosphoric acid for 15s and rinsed for 20s. Half the surface was maintained moist and the other half was air-dried for 30s. Each adhesive was applied simultaneously to both halves, left undisturbed for 30s and light-cured. Four-mm resin build-ups were constructed incrementally. After storage in water at 37 degrees C for 24h, slabs were produced by transversal sectioning and trimmed to an hourglass shape (0.8mm2). Half of the specimens were tested in tension at 0.6mm/min immediately after trimming and the other half after 3 months of water storage. Data were analyzed by two-way ANOVA and SNK for each material. RESULTS: Both moisture and storage affected BS to dentin, and was material-dependent. Dry bonding affected mostly the acetone-based adhesives. Larger reductions in bond strength were associated with dry bonding after 3 months of water storage. SIGNIFICANCE: Wet bonding resulted in more stable bonds over 3 months of water storage for most of the materials tested.