NaF Inhibits Matrix-Bound Cathepsin-Mediated Dentin Matrix Degradation

Abstract

Matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs) degrade the collagen fibrils of demineralized dentin. Sodium fluoride (NaF) has previously been shown to inhibit recombinant MMP-2 and MMP-9. This study aimed to evaluate the efficacy of NaF on the inhibition of dentin-bound MMPs and CCs. Dentin beams were completely demineralized in 10% phosphoric acid. The baseline total MMP activity and dry masses were measured. Beams were assigned to test groups based on similar MMP activity and dry mass (n = 10/group), and incubated in artificial saliva (control) or artificial saliva with NaF containing 6-238 m<smlcap>M</smlcap> fluoride for 1, 7 and 21 days. The dry mass loss and MMP activities were reassessed at each time point. The proteolytic activity was screened by gelatin zymography. ICTP and CTX released to the incubation medium were analyzed as indices of MMP and cathepsin K activity, respectively. The beams were examined under scanning electron microscopy. All NaF doses reduced the dry mass loss after 21 days (p < 0.05). NaF inhibition of the total MMP activity ranged between 5 and 80%. In gelatin zymography, the bands of MMP-2 and MMP-9 became less prominent with increasing NaF levels. NaF did not decrease the released ICTP (p > 0.05). Less CTX release was detected with F ≥179 m<smlcap>M</smlcap> (p < 0.05). CaF₂-like minerals were observed on the beams. High levels of NaF may slow the degradation of the dentin matrix due to the inhibition of cathepsin K. Fluoride does not seem effective in the direct inhibition of proteolysis by dentin matrix-bound MMPs.

Effects of zinc fluoride on inhibiting dentin demineralization and collagen degradation <i>in vitro</i>: A comparison of various topical fluoride agents

“…It should be noted that the immersion of EDTA-demineralized dentin in artificial saliva for up to several days or weeks did not induce remineralization [31][32][33] . On the other hand, there is a study revealed that demineralized dentin immersed in artificial saliva for up to 21 days showed constant (slight) activity of endogenous collagenases, comparing to 1-day immersion 34) . Therefore, it could be assumed that activity of endogenous collagenases would be minimum and the properties of collagen in 24-h immersion of Control group would not be different from 30-s immersion.…”

Ecological Hypothesis of Dentin and Root Caries

“…These phenomena happen in parallel with a continuous degradation of dentin matrix by bacterial and host-derived proteases. In vitro demineralized dentin matrix can be self-degraded by endogenous matrix-embedded proteases without the presence of bacteria [Brackett et al, 2015;Seseogullari-Dirihan et al, 2015;Altinci et al, 2016]; however, in in vivo dentin caries, bacteria are always present, at least in the infected layer of the carious dentin, and inevitably contribute to further degradation of matrix through their proteolytic/ peptidic and metabolic activity. In both enamel and dentin caries bacterial acid production initiates the processes resulting in caries.…”

In vivo evaluation of inflammation and matrix metalloproteinase expression in dental pulp induced by luting agents in dogs

“…Currently, deterioration can be explained by the activation of endogenous enzymes such as MMPs present in the dentin, most likely due to the acidic properties of the adhesive systems. 34,35 Furthermore, we believe that, in general, the cementing agents used in the present study should not be used directly on the exposed pulp tissue. Although KC can be applied in deep dentin, RU should be preceded by the use of a protective agent on the pulp wall prior to cementation.…”