2011 Volume 54 Issue 1 Pages 33-39
In recent years, one-bottle type one-step adhesives have been developed to simplify adhesion procedures. Although their adhesiveness has been investigated, details of the interaction between tooth component and acidic monomers employed in these adhesives have still not been clarified. This study examined the details of the interaction between the acidic monomer employed in G-Bond Plus and tooth component by comparing the changes in the 13C NMR profiles obtained before and after reaction with hydroxyapatite and dentin particles using carbon-13 nuclear magnetic resonance (13C NMR). The effect of the amount of tooth apatite demineralized by acidic monomer on the shear bond strength to enamel and dentin was then discussed by comparing the results obtained for G-Bond. Hydroxyapatite (HAP-200, Taihei Chemical Industrial) or bovine crown dentin particles of 0.400g was suspended in 2.000g of G-Bond Plus or G-Bond (GC), and these suspensions were then vibrated for 10 minutes. After centrifuging the suspensions, 13C NMR spectra of the supernatant solution of adhesives were observed using an EX 270 spectrometer (Japan Electron Optics Laboratory). The ratio of intensity of the NMR peak of the vinyl methylene carbon for the acidic monomer employed in G-Bond Plus or G-Bond to the NMR peak of that for TEGDMA (triethylene glycol dimethacrylate) detected in the 13C NMR spectrum was determined before and after reaction with hydroxyapatite or dentin particles. The reduction in the peak intensity for acidic monomer was determined by dividing the difference in the intensity ratio obtained before and after reaction by the intensity ratio obtained before reaction. The reduction was determined as a ratio of demineralization of tooth apatite by acidic monomer. The bond strength of G-Bond Plus or G-Bond to the ground enamel and dentin was measured. When G-Bond Plus interacted with hydroxyapatite or dentin, the demineralization ratio by acidic monomer was 22.0% and 66.0%, respectively. G-Bond Plus exhibited a greater demineralization ratio than G-Bond, and also exhibited a 28% greater shear bond strength than G-Bond. However, the bond strength of G-Bond Plus to the dentin was almost the same as that of G-Bond. It was concluded that G-Bond Plus, which exhibited a greater demineralization ratio of tooth apatite than G-Bond, provided enamel bond strength but not dentin bond strength.
