Proteolytic degradation of demineralized dentin occurs due to the catalytic activity of dentin matrix-bound matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs). This degradation process takes role in the progression of caries and erosive lesions, as well as the failure of resin-dentin adhesive interfaces. NaF has been previously shown as an effective inhibitor of salivary MMP-2 and -9. Therefore, in this thesis, NaF, KF and CaF2 were systematically screened to investigate the efficacy of fluoride on the inhibition of dentin matrix-bound MMPs and CCs in order to prevent the collagenolytic breakdown of demineralized dentin matrices, and to improve the stability of adhesive interfaces. Degradation of demineralized dentin subjected to NaF, KF and CaF2 with a wide range of concentrations has been systematically screened using total MMP activity assay, gelatin zymography, dry mass loss and the quantitative measurements of collagen degradation products involving ICTP, CTX and hydroxyproline, and scanning electron microscopy analysis. Bonding stability to phosphoric acid-etched and NaF, KF and CaF2 treated dentin surface was examined by a microtensile strength test set-up.

According to the results, NaF, KF, or CaF2 did not prevent the MMP-dependent degradation of demineralized dentin. High levels of NaF and KF was effective in the long-term inhibition of dentin matrix-bound CCs. However, since MMPs are the major enzyme groups responsible from the collagen degradation in dentin, only CCinhibition was not sufficient for the prevention of demineralized dentin degradation. NaF and KF treatment of acid-etched dentin surface might be beneficial for the durability of resin-dentin adhesive interfaces by slowing down the breakdown of insufficiently resin infiltrated collagen fibrils, probably via silencing MMPs and CCs.