Bonding effectiveness of composite-dentin interfaces after mechanical loading with a new device (Rub&Roll).

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Adhesive Dentistry

Background:

• Dental restorations require strong adhesion between restorative materials and tooth structure.
• Evaluating the long-term durability of adhesive systems under mechanical stress is crucial for clinical success.
• New devices for simulating intraoral conditions aid in material testing.

Purpose of the Study:

• To assess the impact of a novel mechanical loading device on the microtensile bond strength (µTBS) of two different adhesive systems to dentin.
• To compare the performance of a self-etch and an etch-and-rinse adhesive system under varying mechanical loading conditions.
• To analyze fracture modes and determine the influence of mechanical cycles on bond integrity.

Main Methods:

• Forty human molars were utilized, divided into two adhesive groups: Clearfil SE Bond (self-etch) and Adper Scotchbond 1XT (etch-and-rinse).
• Samples underwent aging through mechanical loading using a new device, with groups subjected to 0 (control), 250,000, 500,000, and 750,000 cycles.
• Microtensile bond strength (µTBS) was measured, and fracture modes were analyzed using Kruskal-Wallis and post hoc tests.

Main Results:

• Both mechanical loading and the type of adhesive system significantly affected µTBS (p<0.001 and p=0.024, respectively).
• Increasing mechanical cycles generally decreased µTBS for both adhesive systems.
• The self-etch adhesive (Clearfil SE Bond) demonstrated significantly higher µTBS compared to the etch-and-rinse system (Adper Scotchbond 1XT) only after 750,000 mechanical cycles.

Conclusions:

• The novel mechanical loading device effectively reduced the bond strength of tested adhesive systems to dentin with increasing cycles.
• Self-etch adhesive systems may offer superior long-term durability under significant mechanical loading compared to etch-and-rinse systems.
• Material differences in bond strength degradation under mechanical stress become apparent only after substantial cyclic loading (750,000 cycles).