Cyclic fatigue of composite restorative materials

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Mechanical Properties of Polymers

Background:

• Dental composites are widely used restorative materials.
• Understanding their mechanical properties, including fracture and stress corrosion, is crucial for clinical longevity.
• Filler particle size is a key factor influencing composite performance.

Purpose of the Study:

• To investigate and evaluate dental composite restorative materials based on filler particle size (microfill, small particle, hybrid).
• To assess their fracture characteristics and susceptibility to stress corrosion.
• To correlate filler type with failure mechanisms under cyclic fatigue.

Main Methods:

• Dental composites were classified by filler particle size: microfill, small particle, and hybrid.
• Materials underwent cyclic fatigue testing in distilled water at 37°C.
• Fracture interfaces were analyzed to determine failure modes.

Main Results:

• No significant trend was observed between the number of cycles to fracture and the cycling load relative to the modulus of rupture.
• Linear regression analysis showed weak correlation for most composites in determining the stress corrosion resistance constant (ranging from 0.80 to 12.05).
• Fracture analysis revealed inter- and intraparticle fractures in small particle and hybrid composites, while microfills fractured between and through prepolymerized particles.

Conclusions:

• Filler particle size influences the fracture behavior of dental composites.
• Stress corrosion resistance varies among different composite types, with weak correlations observed.
• Understanding these fracture mechanisms is essential for improving the durability of dental restorative materials.