Effect of Different Light Intensities on the Compressive Strength of Posterior Composite Resins

Abstract

Background: The clinical success and longevity of composite resins are highly dependent on the degree of polymerization, which is influenced by various factors, including the light intensity of the light-curing unit. Inadequate polymerization can compromise mechanical properties, particularly in posterior regions. Although light emitting diode (LED) units are commonly used in clinical practice, there is limited evidence regarding the impact of different light intensities on the compressive strength (CS) of current composite resins.

Methods: A total of 135 cylindrical specimens (n=45 per composite resin) were fabricated using standardized silicone molds (4 mm diameter × 6 mm height). Three composite resins—Filtek Z250 (3M ESPE), Estelite Posterior (Tokuyama), and G-ænial posterior (GC)—were light-cured with an LED unit (Elipar DeepCure-S, 3M ESPE) at 3 different light intensities (60%, 80%, 100%), following manufacturer-recommended durations. Specimens were stored at 37°C in 100% humidity for 24 hours before testing. Compressive strength was measured using a universal testing machine at a crosshead speed of 1 mm/min. Two-way ANOVA and Tukey Tukey’s honest significant difference (HSD) tests were used for statistical analysis (P=.05).

Results: Both light intensity and composite resin significantly affected CS (P < .05), whereas their interaction was not significant. Filtek Z250 and Estelite Posterior showed higher CS than G-ænial Posterior at all light intensities. Compressive strength increased with higher light intensity across all groups.

Conclusion: The increase in CS observed with higher light intensity emphasizes the importance of tailoring polymerization protocols to the unique characteristics of each composite resin.

Cite this article as: Yurdagüven GY. Effect of different light intensities on the compressive strength of posterior composite resins. Essent Dent. 2026, 5, 0078, doi:10.5152/EssentDent.2026.25078.