# Effect of magnetic MMP removal on long‐term dentin collagen stability

## TL;DR

A new magnetic treatment effectively removes enzymes that break down dentin collagen, leading to longer-lasting dental bonds.

## Contribution

A novel magnetic method for removing dentinal MMPs is introduced, offering improved bonding durability.

## Key findings

- MAG-2 treatment provided stable bond strength over 1 year, outperforming CHX and placebo.
- MAG-2 significantly reduced MMP activity and collagen degradation compared to other treatments.
- Magnetic nanoparticle concentration of 2 wt% was most effective for MMP removal.

## Abstract

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.