Correlation Between Gingival Fibroblast Cell Viability and Degree of Conversion of Resin Composites at Different Light-Curing Tip Distances Publisher



Hashemian A ; Hodjat M ; Behroozibakhsh M
Source: Journal of Oral Biology and Craniofacial Research Published:2025

Abstract

Objective: This study aimed to evaluate the effect of light-curing tip distance on the degree of conversion (DC), as well as on the cell viability. The study also aimed to assess the correlation between DC% and cell viability at different light-curing tip distances. Materials and methods: Nanocomposite discs were cured using an LED light-curing unit at distances of 0 mm (G0), 2 mm (G2), 4 mm (G4), 6 mm (G6), and 8 mm (G8) for 20 s. The DC was measured using ATR-FTIR analysis. Cell viability was assessed through MTT assay on human gingival fibroblasts. The results were analyzed using one-way ANOVA and Pearson correlation analysis. Results: The DC at the surface was significantly higher than the bottom of the samples in all groups (p < 0.001). The DC on both surfaces decreased as the distance between the light-curing unit and the sample surface increased. Moreover, with an increase in distance, the cell viability decreased. This difference was statistically significant in all groups, except for the G0 and G2 groups (p < 0.001). The results of Pearson correlation analysis showed a positive and statistically significant correlation between cell viability and DC% at both surfaces (p < 0.05). Furthermore, a negative and statistically significant correlation was observed between tip distance and DC% at both top and bottom surfaces as well as cell viability(p < 0.05). Conclusion: Increasing the distance from the light-curing tip adversely affects composite polymerization and biocompatibility, likely due to insufficient curing and subsequent monomer and nanoparticle release. This study emphasizes the importance of optimal curing conditions. © 2025 Elsevier B.V., All rights reserved.