Material-Dependent Microhardness Response to Preheating in Nanoparticulate Composite Resins Cured with High-Intensity...

Area of Science:

• Restorative Dentistry
• Materials Science

Background:

• Composite resins are esthetic and easy-to-use dental restorative materials.
• Preheating composite resins may improve their flowability, conversion, and mechanical properties.
• High-power LED light curing is a standard polymerization method.

Purpose of the Study:

• To evaluate the effect of preheating on the microhardness of three nanoparticulate composite resins.
• To compare the microhardness of IPS Empress Direct, Filtek Z350 XT, and Forma after preheating.
• To assess the impact of preheating on composite resin mechanical performance.

Main Methods:

• Sixty disc-shaped samples (20 per material) were fabricated.
• Samples were divided into preheated and non-preheated groups.
• Knoop microhardness testing was performed after storage in distilled water.

Main Results:

• Preheating significantly increased microhardness in IPS Empress Direct (32.8%) and Filtek Z350 XT (5.8%).
• Forma composite resin showed no significant change in microhardness after preheating.
• The results indicate a material-specific response to preheating.

Conclusions:

• Preheating can enhance the microhardness of certain composite resins.
• The material-dependent effect of preheating on microhardness was confirmed.
• Preheating may improve the mechanical performance of specific dental composites.