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Updated: Jan 10, 2026

Multiplexed Single-molecule Force Proteolysis Measurements Using Magnetic Tweezers
Published on: July 25, 2012
Effect of magnetic MMP removal on long-term dentin collagen stability
Walter Zenobi1, Salvatore Sauro2, Davino Machado Andrade Neto3
1Postgraduate Program of Dentistry, Federal University of Ceara, Fortaleza, Brazil.
None:
Several matrix metalloproteinase (MMP) inhibitors have been investigated for their ability to improve dentin-bond longevity. However, MMPs tend to reactivate over time, especially using simplified etch-and-rinse adhesives. This study investigated a novel magnetic removal of dentinal MMPs on bonding durability, MMP inhibition and collagen degradation. Magnetic nanoparticles (Fe3O4) were synthesized, characterized, and incorporated in water-based gels at 2 wt% (MAG-2) or 20 wt% (MAG-20). A placebo and 2 wt% chlorhexidine (CHX) digluconate gel were employed as control treatments. Human teeth were acid-etched, pretreated with gels (external magnetic motion was created in the MAG groups), and bonded to composite using a simplified adhesive. Specimens were subjected to microtensile bond strength test after 24 h or 1 year of water storage. Interface release of hydroxyproline was assessed. Presence of MMPs was analyzed by confocal microscopy in situ zymography. Data were statistically analyzed using two-way ANOVA and Tukey's test. MAG-2 was the only treatment providing stable bond strength, revealing lower MMP activity than CHX. MAG-2 produced an evident removal of MMPs compared to CHX, MAG-20, and placebo. The innovative magnetic treatment of dentin was able to effectively remove MMPs when used at a 2 wt% concentration, arresting dentin collagen degradation at the dentin-bonded and achieving stable bonding over time.
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