Effects of proanthocyanidin-functionalized hydroxyapatite nanoparticles on dentin bonding.

Area of Science:

• Biomaterials Science
• Dental Materials
• Nanotechnology in Dentistry

Background:

• Dentin bonding is susceptible to degradation by endogenous enzymes, primarily matrix metalloproteinases (MMPs).
• Nanoparticles offer potential for improving dental adhesive performance and durability.
• Proanthocyanidins (PA) are known for their MMP inhibitory properties.

Purpose of the Study:

• To investigate the efficacy of proanthocyanidin-functionalized hydroxyapatite nanoparticles (nHAp_PA) as a dentin pretreatment.
• To evaluate the impact of nHAp_PA on microtensile bond strength (µTBS) and MMP activity after aging.
• To determine the optimal concentration of nHAp_PA for enhanced dentin bonding.

Main Methods:

• Human dentin blocks were pretreated with varying concentrations of nHAp_PA (2%, 6.5%, 15%) or controls.
• A self-etch adhesive and resin composite were applied, followed by pH-cycling and artificial aging for 24 hours and 6 months.
• Microtensile bond strength (µTBS) and endogenous enzymatic activity (MMP-2, MMP-9) were assessed using µTBS, gelatin zymography, and in situ zymography.

Main Results:

• All nHAp_PA concentrations significantly increased µTBS at 24 hours compared to controls, with no concentration-dependent difference.
• Artificial aging reduced bond strength, but the 2% nHAp_PA group maintained significantly higher µTBS than controls after 6 months.
• nHAp_PA pretreatment effectively reduced MMP-2 and MMP-9 activity, comparable to the negative control after 6 months of aging.

Conclusions:

• Dentin pretreatment with nHAp_PA enhances the bonding performance of self-etch adhesives.
• nHAp_PA effectively inhibits endogenous MMP activity in dentin, contributing to improved bond durability.
• The 2% nHAp_PA concentration shows promising results for long-term dentin bonding stability.