Changes in resin-infiltrated dentin stiffness after water storage

Area of Science:

• Polymer science
• Biomaterials science
• Dental materials science

Background:

• Water sorption plasticizes polymers, reducing mechanical properties.
• The degree of reduction correlates with resin polarity.
• Understanding this in dental adhesives is crucial for restoration longevity.

Purpose of the Study:

• To test if hydrophilic characteristics reduce flexural modulus reduction in resin-infiltrated dentin after water storage.
• To investigate the relationship between hydrophilicity and mechanical property changes in dental adhesive resins.

Main Methods:

• Fabricated polymer beams and resin-infiltrated dentin models using three increasingly hydrophilic resin blends.
• Tested flexural moduli using a miniature three-point flexure device.
• Stored samples in water for 1-4 weeks to assess property changes.

Main Results:

• Flexural modulus reductions were more extensive in resin-infiltrated dentin models than in polymer beams.
• More hydrophilic macro-hybrid layers showed greater percent reductions in flexural modulus.
• The rate of reduction correlated with Hoy's solubility parameters for total (delta(t)) and polar (delta(p)) forces.

Conclusions:

• Hydrophilicity significantly influences the water-induced mechanical property degradation of resin-infiltrated dentin.
• The findings provide insights into the long-term stability of dental adhesive restorations.
• Material selection based on hydrophilic characteristics is important for predictable clinical performance.