Effect of repair systems on dentin bonding performance.

Area of Science:

• Dental Materials Science
• Adhesive Dentistry
• Biomaterials

Background:

• Effective dentin bonding is crucial for the longevity of dental restorations.
• Self-etch adhesive systems offer simplified application protocols.
• Understanding pre-treatment effects on dentin bonding is essential for clinical success.

Purpose of the Study:

• To evaluate the influence of phosphoric acid etching, metal primer, and silane coupling agent application on the dentin bonding performance of a 2-step self-etch adhesive.
• To assess the impact of these pre-treatments on the durability of the dentin-adhesive interface under thermocycling and acid-base challenge.

Main Methods:

• Human dentin surfaces were pre-treated with no agent (Control), 40% phosphoric acid (K), metal primer (AP), or silane coupling agent (PB).
• Specimens were bonded with a 2-step self-etch adhesive, sectioned, and divided into non-thermocycled and thermocycled subgroups.
• Microtensile bond strength (µTBS) testing and scanning electron microscopy (SEM) analysis after an acid-base challenge were performed.

Main Results:

• Phosphoric acid (K) and metal primer (AP) groups showed statistically lower bond strengths compared to the control.
• Silane coupling agent (PB) groups exhibited significantly lower bond strengths than the control, both with and without thermocycling.
• SEM analysis revealed an acid-base resistant zone (ABRZ) in all groups, with the phosphoric acid group showing funnel-shaped erosion beneath the ABRZ.

Conclusions:

• Pre-treatment with phosphoric acid or metal primer compromises the dentin bonding of this 2-step self-etch adhesive system.
• Silane coupling agent pre-treatment also negatively affects bond strength, indicating potential incompatibility or degradation.
• The findings suggest that specific pre-treatments may alter the integrity of the hybrid layer and the ABRZ, impacting long-term bond durability.