Ultra-high-speed videography of resin-dentin interface failure dynamics under tensile load

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Fracture Mechanics

Background:

• Assessing the bond strength and failure modes at the resin-dentin interface is crucial for dental restorative materials.
• Micro-tensile bond strength (μTBS) testing is a standard method, but visualizing dynamic fracture events in real-time presents challenges.

Purpose of the Study:

• To visualize fracture phenomena at the resin-dentin interface during μTBS testing using ultra-high-speed (UHS) videography.
• To evaluate the applicability of UHS videography for failure-mode analysis in comparison to traditional methods.

Main Methods:

• Human dentin surfaces were bonded using Clearfil SE Bond in self-etching (SE) or etch-and-rinse (ER) modes.
• Samples underwent μTBS testing, with fracture events captured using UHS videography at 299,166 frames per second.
• Failure modes were classified using both UHS videography and scanning electron microscopy (SEM), with statistical analysis performed.

Main Results:

• Crack propagation speeds exceeded 1,500 km/h.
• UHS videography and SEM showed no significant difference in failure mode distribution for the SE mode.
• A significant difference was observed between UHS videography and SEM for the ER mode.
• Both methods identified significant differences in cohesive failures within the adhesive and at the adhesive-composite interface between SE and ER modes.

Conclusions:

• UHS videography effectively visualizes fracture dynamics at the resin-dentin interface under tensile load.
• While UHS videography's resolution is insufficient for precise failure mode classification compared to SEM, it provides detailed information on fracture origin and propagation.
• UHS videography shows potential as a complementary tool for analyzing adhesive bond failures in dentistry.