Is dentin analogue material a viable substitute for human dentin in fatigue behavior studies?

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Mechanical Engineering

Background:

• Accurate simulation of human dentin is crucial for evaluating dental restorative materials.
• Lithium disilicate ceramics are widely used in dental restorations.
• Understanding fatigue performance on different substrates is essential for clinical longevity.

Purpose of the Study:

• To compare the fatigue performance of lithium disilicate ceramic bonded to human dentin versus glass fiber-reinforced epoxy resin (GFRER).
• To evaluate the effect of various surface conditioning methods on fatigue performance.
• To determine if GFRER can reliably simulate human dentin for fatigue testing.

Main Methods:

• Lithium disilicate ceramic discs were cemented onto human dentin and GFRER substrates.
• Substrates underwent different surface treatments: no conditioning, hydrofluoric acid, phosphoric acid, or sandblasting.
• Specimens were subjected to thermocycling and a cyclic fatigue test; failure load and cycles were recorded.

Main Results:

• Human dentin substrates exhibited significantly lower fatigue load and cycles to failure than GFRER substrates.
• All surface treatments modified substrate topography, but GFRER did not replicate dentin's fatigue behavior.
• Fractographic analysis consistently showed radial crack failure patterns.

Conclusions:

• Glass fiber-reinforced epoxy resin is not a suitable substitute for human dentin in simulating lithium disilicate fatigue performance.
• Cementing lithium disilicate on dentin analogues may overestimate fatigue failure load values.
• Surface conditioning methods impact substrate topography but do not fully bridge the gap between GFRER and dentin fatigue resistance.