Related Experiment Video
Updated: May 2, 2026
Roughness Impact of Piezoelectric Dental Scaler on Two Distinct Flowable Composite Filling Materials
Published on: January 10, 2025
Effect of preheating on microhardness and viscosity of 4 resin composites
Karen V Ayub, Gildo C Santos, Amin S Rizkalla
1Schulich School of Medicine & Dentistry, Western University, London, ON.
Objective:
This study was undertaken to determine the effect of temperature on the microhardness and viscosity of 4 resin composite materials.
Methods:
To investigate microhardness, samples of each of the 4 composite materials, prepared by standard insertion of resin into prefabricated moulds, were divided into 2 groups (n = 10 per group). On the first group, the resin composite materials were inserted into the moulds at room temperature and cured. On the second group, the resin composite materials were pre-heated in a heating device, inserted into the moulds and immediately cured. Microhardness after curing (both immediately and after 24 hours of storage) was determined (using a 300 g load applied for 10 seconds) and averaged for 5 randomly selected points on the top and bottom surfaces of each sample. To investigate viscosity, 0.5 g samples of room temperature or preheated resin composite (n = 15 per group) were placed under a 454 g load for 45 seconds before light-curing (40 seconds). After curing, each sample was photographed and the surface area calculated. Data were analyzed by t tests or one-way analysis of variance and Tukey's test.
Results:
Preheating the resin composites increased the microhardness and decreased the viscosity of the samples. Filtek Supreme Ultra resin composite had the highest mean microhardness, and Vit-l-escence resin composite had the lowest viscosity.
Conclusions:
The effects of preheating resin composites may allow easier placement of restorations and greater monomer conversion.
