A Defined-Area Bonding Approach for Microtensile Testing: A Reliable Alternative to Monoblock Sectioning for...

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Restorative Dentistry

Background:

• Microtensile bond strength (μTBS) testing is crucial for evaluating dental adhesives.
• Conventional monoblock sectioning technique (MST) is challenging for brittle CAD/CAM materials like zirconia.
• Reproducibility issues arise with MST for hard and brittle dental substrates.

Purpose of the Study:

• To compare a novel defined-area bonding (DAB) method with MST for specimen preparation.
• To assess the reliability of DAB for μTBS testing of CAD/CAM materials.
• To determine if DAB can overcome limitations of MST in testing brittle materials.

Main Methods:

• CAD/CAM blocks and core materials were bonded using ESTECEM II or Panavia V5.
• MST involved bonding blocks then sectioning into beams; DAB involved pre-shaping sticks and bonding within a 1 mm² area.
• Evaluated μTBS, failure modes, and fracture/interface morphology via SEM.

Main Results:

• MST yielded significantly higher μTBS than DAB (p < 0.001).
• DAB bond strengths were statistically equivalent to MST peripheral values.
• Over 80% of failures were cohesive within the resin cement.
• SEM showed uniform cement thickness and similar fracture patterns in DAB specimens.

Conclusions:

• DAB provides bond strengths comparable to MST peripheral regions with consistent fracture characteristics.
• DAB requires minimal cutting, presenting a promising and reproducible method for μTBS testing of high-hardness materials.
• DAB addresses the limitations of sectioning brittle CAD/CAM materials for bond strength evaluation.