Dentin Bonding Durability of Four Different Recently Introduced Self-Etch Adhesives

Area of Science:

• Dental Materials Science
• Adhesive Dentistry
• Polymer Chemistry

Background:

• Self-etch adhesives (SEAs) are crucial for modern dental restorations.
• Evaluating the long-term durability and polymerization of SEAs under simulated intraoral conditions is essential.
• Understanding the impact of thermal cycling on bond strength and conversion is key to predicting clinical performance.

Purpose of the Study:

• To compare the bonding durability of two-step and one-step SEAs to dentin after 24 hours and thermal cycling.
• To measure the in situ degree of polymerization conversion (DC) of the evaluated SEAs.
• To assess the influence of aging and thermal stress on the micro-tensile bond strength (µTBS) of different SEAs.

Main Methods:

• Four SEAs (Clearfil SE Bond 2, G2-Bond Universal, Scotchbond™ Universal Plus Adhesive, Clearfil Universal Bond Quick) were tested on bovine dentin.
• Specimens underwent 0, 10,000, or 20,000 thermal cycles (TC) before micro-tensile bond strength (µTBS) testing.
• In situ degree of polymerization conversion (DC) was measured using laser Raman microscopy.

Main Results:

• G2-Bond Universal (G2B) with 10,000 TC and Scotchbond™ Universal Plus Adhesive (SBU) with 20,000 TC showed significantly higher µTBS than controls (TC0).
• SBU exhibited significantly lower µTBS than G2B after 10,000 TC, with G2B and SBU showing more adhesive failures post-TC.
• Mean DC% varied among adhesives, with the new MDP- and HEMA-free two-step SEA performing comparably to the gold standard.

Conclusions:

• Certain universal SEAs demonstrate improved bonding durability with aging and thermal stress.
• Increased adhesive failures in some SEAs after thermal cycling suggest potential long-term challenges.
• While promising, further improvements in self-etch adhesive formulations are needed for optimal clinical longevity.