Assessment of Sealing Ability and Degradation Resistance of a Hydrogel-Based Root Canal Filling Material Using a Bacterial Leakage Model and SEM Analysis.

Background
This study evaluated the sealing ability and degradation resistance of a novel hydrogel-based, low-viscosity, light-curable obturation material compared with gutta-percha combined with an epoxy resin-based sealer using a bacterial leakage model and scanning electron microscopy (SEM) analysis.
Methods
Thirty-seven extracted single-rooted bovine incisors were allocated into four groups: gutta-percha + epoxy resin sealer (n = 12), hydrogel-based material (n = 10), positive control with empty canals (n = 11), and negative control (n = 4). Bacterial leakage was assessed using a two-chamber model inoculated with Enterococcus faecalis. Survival times were analyzed using nonparametric tests. For degradation analysis, 30 hydrogel specimens (n = 6 per medium) were incubated in phosphate-buffered saline (PBS), brain heart infusion (BHI) broth, E. faecalis suspension, sterile-filtered saliva, or pH 10 carbonate buffer. SEM-based Feret diameter measurements were obtained after 1, 8, and 30 days and analyzed using Kruskal-Wallis and Holm-adjusted Mann-Whitney U tests.
Results
The first leakage occurred after 11 days in the gutta-percha group and after 58 days in the hydrogel group. Forty percent failure was observed after 22 days for gutta-percha and after 121 days for the hydrogel material (p < 0.001). Mean Feret diameter increased most markedly under alkaline conditions (Δ = +0.100  μm from Day 1 to Day 30; p < 0.001), whereas changes in PBS, BHI, E. faecalis, and saliva remained below 0.05 μm over 30 days.
Conclusions
The hydrogel-based obturation material demonstrated significantly prolonged resistance to bacterial penetration and maintained structural stability under biologically relevant incubation conditions. Further long-term and in vivo studies are required to confirm clinical performance.