Effects of potassium and sodium fluoride in different concentrations on micro-shear bond strength and inhibition of demineralization

Abstract

The aim of this study was to investigate the effects of potassium fluoride (KF) and sodium fluoride (NaF) in different concentrations on micro-shear bond strength (µSBS) and their protective effects against acid. The enamel blocks were treated with several concentrations of KF and NaF. For µSBS, Clearfil SE Bond 2 was applied to the treated surface and resin composite was light-cured, then examined using a universal testing machine. For acid resistance test, the specimens were immersed in acidic solution (pH 4.5), then examined under 3D confocal laser scanning microscope (CLSM). In µSBS, KF at 1,000, 9,000, and 10,000 ppm did not show differences compared with the control, while other concentrations of KF and NaF led to decreased µSBS. Higher concentrations of NaF and KF showed higher resistance to the acid challenge. So, we concluded that various concentrations of KF and NaF solutions had specific effects on µSBS and acid resistance.