Long-Term In Vitro Adhesive Properties of Two Universal Adhesives to Dentin

Area of Science:

• Dental materials science
• Adhesive dentistry

Background:

• Universal adhesives offer versatile application modes (etch-and-rinse/self-etch).
• Their bonding effectiveness and durability depend on composition and strategy.
• Comparative studies are crucial for understanding their clinical performance.

Purpose of the Study:

• To evaluate microtensile bond strength (µTBS) and nanoleakage (NL) of two universal adhesives.
• To assess in situ degree of conversion (DC) with different application strategies.
• To compare universal adhesives against a gold-standard two-step self-etch adhesive.

Main Methods:

• Two universal adhesives (Scotchbond Universal Adhesive, Xeno Select) and one control (Clearfil SE Bond) were tested.
• Adhesives were applied using etch-and-rinse and self-etch strategies on human dentin.
• µTBS and NL were evaluated immediately and after 6-month aging; DC was quantified in situ.

Main Results:

• Scotchbond Universal Adhesive and Clearfil SE Bond demonstrated significantly higher µTBS and lower NL than Xeno Select.
• These results were consistent regardless of evaluation time and application strategy.
• Xeno Select in self-etch mode exhibited the lowest degree of conversion.

Conclusions:

• The performance of universal adhesives in dentin is material-dependent, not solely strategy-dependent.
• Xeno Select showed inferior bonding performance compared to Scotchbond Universal Adhesive.
• Material selection is critical for predictable long-term bonding outcomes.