Zymography of Hybrid Layers Created Using Extrafibrillar Demineralization.

Area of Science:

• Biomaterials Science
• Dental Adhesion
• Remineralization

Background:

• Improving resin-dentin bonding is crucial for durable dental restorations.
• The hybrid layer (HL) is key to bonding, but susceptible to degradation.
• Enzymatic activity within the HL can compromise bond integrity over time.

Purpose of the Study:

• To evaluate the gelatinolytic (enzymatic) activity within hybrid layers created using the chelate-and-rinse bonding technique.
• To compare the effectiveness of polymeric chelators versus traditional phosphoric acid etching.
• To assess the impact of dry-bonding and wet-bonding techniques on enzymatic activity.

Main Methods:

• Dentin specimens were conditioned with phosphoric acid (control) or polymeric chelators (PAANs).
• Bonding was performed using dry-bonding and wet-bonding techniques.
• In situ zymography and confocal laser-scanning microscopy assessed gelatinolytic activity in hybrid layers after 24-h storage and thermomechanical cycling.

Main Results:

• Phosphoric acid etching showed detectable enzymatic activity, higher in dry-bonding than wet-bonding.
• Chelator conditioning (PAANs) resulted in minimal fluorescence signals, indicating near-absence of enzymatic activity in the hybrid layer.
• Enzymatic activity increased after thermomechanical cycling in the phosphoric acid group, but remained low in the chelator group.

Conclusions:

• The chelate-and-rinse bonding concept effectively minimizes matrix-bound collagenolytic activities in the hybrid layer.
• This technique promotes durable resin-dentin bonding by preserving intrafibrillar minerals and inhibiting endogenous protease activity.
• The findings suggest a potential for enhanced longevity of dental restorations using this novel bonding approach.