NaF Inhibits Matrix-Bound Cathepsin-Mediated Dentin Matrix Degradation

Area of Science:

• Biomaterials Science
• Dental Research
• Biochemistry

Background:

• Matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs) are key enzymes responsible for collagen degradation in demineralized dentin.
• Sodium fluoride (NaF) has demonstrated inhibitory effects on certain recombinant MMPs, suggesting potential therapeutic applications in preventing dentin degradation.

Purpose of the Study:

• To investigate the effectiveness of sodium fluoride (NaF) in inhibiting dentin-bound MMPs and CCs.
• To evaluate the impact of varying NaF concentrations on dentin matrix degradation over time.

Main Methods:

• Demineralized dentin beams were incubated with different concentrations of NaF in artificial saliva for up to 21 days.
• Dry mass loss, total MMP activity, and specific enzyme activity (ICTP for MMPs, CTX for cathepsin K) were measured.
• Gelatin zymography and scanning electron microscopy were employed for detailed analysis.

Main Results:

• All tested NaF concentrations significantly reduced dry mass loss after 21 days.
• NaF exhibited dose-dependent inhibition of total MMP activity, ranging from 5% to 80%, with reduced MMP-2 and MMP-9 activity observed.
• NaF did not significantly inhibit MMP activity (ICTP release), but higher concentrations (≥179 mM) reduced cathepsin K activity (CTX release).
• CaF2-like mineral deposition was observed on dentin surfaces.

Conclusions:

• High concentrations of NaF can mitigate dentin matrix degradation, primarily through the inhibition of cathepsin K.
• Fluoride appears to have limited direct inhibitory effects on the proteolytic activity of dentin matrix-bound MMPs.
• NaF treatment leads to the formation of CaF2-like minerals on dentin, which may contribute to matrix stabilization.