A novel dentin bond strength measurement technique using a composite disk in diametral compression

Area of Science:

• Biomaterials Science
• Dental Materials Science
• Mechanical Engineering

Background:

• Predicting clinical failure of dental restorations bonded to dentin requires improved methods.
• Current techniques for measuring dentin bond strength have significant limitations, including stress distribution deviations and high variability.

Purpose of the Study:

• To evaluate a novel test specimen and method for measuring post-dentin interfacial bond strength.
• To assess the feasibility of the modified Brazilian disk test for assessing intracanal post bonding.

Main Methods:

• A modified Brazilian disk test was employed using resin composite disks containing dentin slices with or without intracanal posts.
• Diametral compression testing was performed, coupled with advanced non-destructive techniques: acoustic emission (AE) and digital image correlation (DIC).
• Finite-element analysis (FEA) was integrated with experimental data to calculate bond/tensile strengths.

Main Results:

• Digital image correlation (DIC) identified initial strain concentration at the post-dentin interface, coinciding with the first acoustic emission (AE) signals.
• Calculated bond/tensile strengths were: 11.2 MPa (fiber posts), 12.9 MPa (metal posts), 8.9 MPa (direct resin fillings), and 82.6 MPa for dentin.
• The modified Brazilian disk test demonstrated simpler specimen preparation, consistent failure modes, and reduced variability in bond strength measurements.

Conclusions:

• The feasibility of using a composite disk in diametral compression to measure post-dentin bond strength has been established.
• This novel method provides a more reliable and consistent approach to evaluating the interfacial bond strength critical for dental restoration longevity.
• The findings support the potential of this technique for predicting clinical failure in dentin-bonded restorations.