Flexural behaviour of post-cured composites at oral-simulating temperatures

Area of Science:

• Dental Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Post-curing treatments enhance mechanical stability in visible light-cured composites.
• Composite material composition significantly influences mechanical properties and stability.

Purpose of the Study:

• To evaluate the flexural strength (FS) of four commercial composite materials after post-curing.
• To assess the impact of temperature and moisture on the FS of different composite formulations.

Main Methods:

• Four composite materials with varying compositions (OCDMA, BisGMA, UDMA-based) were post-cured.
• Flexural strength was measured in water across a temperature range (12-50°C) and in air at 25°C.
• Statistical analysis included ANOVA and Duncan's test.

Main Results:

• Flexural strength decreased by 20-40% with increasing temperatures in water for most composites (P < 0.01).
• Conquest C & B (OCDMA-based) showed no significant decrease in FS with rising temperature.
• Wet conditions at 25°C resulted in higher FS than dry conditions for all tested materials.

Conclusions:

• UDMA-based composites are more susceptible to softening in water and temperature fluctuations than BisGMA- or OCDMA-based materials.
• The oral environment, particularly moisture and temperature, can significantly affect post-cured composite mechanical properties.
• Material composition is a critical factor determining the extent of degradation and property changes in composites.