Ceramic Bonding Interface under Shear-Compression Stress: Ultra-High-Speed Imaging Contribution.

Area of Science:

• Materials Science
• Biomaterials Engineering
• Dental Materials

Background:

• Understanding resin-ceramic bond failure is crucial for dental restorations.
• Existing methods lack the resolution to capture rapid interfacial events.
• Lithium disilicate (LiSi2) is a common ceramic material in dentistry.

Purpose of the Study:

• To visualize and characterize failure phenomena at the resin-LiSi2 bonding interface using ultra-high-speed imaging (UHSI).
• To compare failure modes between a gold-standard bonding agent (Monobond Plus [MB]) and a non-toxic alternative (Monobond Etch & Prime [MEP]).
• To analyze the influence of shear-compression stress on interfacial integrity.

Main Methods:

• Utilized an advanced UHSI camera capable of unprecedented frame rates (300,000 fps) and resolution.
• Employed finite element analysis (FEA) to confirm a combined shear and compression stress state at the bonding interface.
• Subjected LiSi2 samples bonded with MB (n=5) and MEP (n=5) to gradual axial compression loading until catastrophic failure.

Main Results:

• UHSI successfully recorded the dynamic failure process at the resin-ceramic interface.
• Debonding was consistently observed as the initial event preceding material breakage.
• Failure initiated at the interface, followed by slippage and subsequent cohesive failure, resulting in a mixed failure mode.
• Both MB and MEP bonding agents exhibited similar failure behaviors.

Conclusions:

• The study provides the first direct visualization of debonding as the primary failure initiation event at the resin-LiSi2 interface.
• The observed mixed failure mode, involving interfacial rupture and cohesive failure, is critical for understanding restoration longevity.
• The non-toxic MEP bonding agent demonstrated comparable performance to the gold-standard MB, suggesting its clinical viability.