Effects of pre-polymerization temperature on the mechanical properties and viscosity of light-cure flowable composite resins for core build-up

This study evaluated the effects of pre-polymerization temperature on the mechanical properties and viscosity of light-cure flowable composite resins for core build-up. Four materials (EverX Flow, BeautiCore LC Injectable, Filtek Fill and Core Flowable Restorative Plus, and iTFC Luminous Core LC Flow) were conditioned at 4, 23, or 60°C. Flexural strength, elastic modulus, fracture toughness, and viscosity were measured. Temperature significantly affected viscosity and, in BeautiCore, Filtek, and iTFC, also influenced flexural strength and fracture toughness. The short fiber-reinforced composite EverX Flow showed superior mechanical performance with consistent temperature stability, while BeautiCore and Filtek demonstrated improved flowability after pre-heating. iTFC exhibited a low modulus and minimal temperature sensitivity. These results indicate that temperature is a critical factor in the clinical performance of flowable composites, with pre-heating enhancing handling through viscosity reduction.