Abstract
To investigate the influence of the contamination on the enamel bonding, the bond strength of the chemical-cured glass ionomer cement to polished or etched enamel with contamination was measured. The bond strengths to polished enamel covered with contaminant (water: 10.9 MPa, saliva: 12.3 MPa, blood: 7.2 MPa) were significantly lower than that of the control (15.1 MPa). And, the bond strengths to etched enamel covered with contaminant (water: 17.2 MPa, saliva: 16.7 MPa, blood: 9.4 MPa) were also significantly lower than that of the control (19.9 MPa). The blood contamination reduced the bond strength to enamel than water and saliva contamination regardless of enamel surface treatment. Although the contaminants reduced the bond strengths of glass ionomer cement, the values were comparable to clinical required bond strength. In the case of control, water and saliva contamination, SEM micrographs revealed that samples of polished enamel had the mixed fracture pattern of bracket-cement and enamel-cement interface failure and the specimens of etched enamel mainly had the bracket-cement interface failure. For the blood contamination, the cohesive fracture of the glass ionomer cement was observed regardless of the enamel surface treatment. These results showed that the chemical-cured glass ionomer cement is available for orthodontic clinical use.
