Synthesis and characterization of calcium-releasing elastomeric resin-based endodontic sealers

Objectives To evaluate the incorporation of halloysite nanotubes (HNTs) loaded with one of two calcium sources (i.e., calcium hydroxide/CaOH 2 or beta-tricalcium phosphate/β-TCP) on the physicochemical and biological properties of an experimental resin-based dual-cured endodontic sealer. Materials and methods HNTs were encapsulated with CaOH 2 or β-TCP at 10 wt.%. HNTs containing CaOH 2 or β-TCP were added into the experimental sealers at 50 wt.%. The control sealers were the calcium-free HNT-modified resin-based experimental sealer and AH Plus™, a commercially available endodontic sealer. Degree of conversion, setting time, flow, film thickness, radiopacity, dimensional stability, and calcium ions release were determined. Antibiofilm properties and cytocompatibility of the formulated sealers and commercial control were also evaluated. One and two-way ANOVA analysis followed by Tukey’s post hoc test was conducted to evaluate the effect of the independent variable on the evaluated properties. Results FTIR confirmed the encapsulation of calcium sources into HNTs. Regarding flow and film thickness, the values obtained from these sealers were in accordance with the specifications provided by ISO 6876. For radiopacity, AH Plus™ achieved the highest radiopacity ( p <0.05). Among the experimental formulations, all experimental HNT-containing compositions exhibited values below 3 mm Al. The experimental sealers showed greater dimensional changes when compared to the commercial (AH Plus™) control. The release of calcium ions was observed for the HNT_CaOH 2 and HNT_β-TCP sealers without statistical differences. Experimental sealers containing HNT_CaOH 2 and HNT_β-TCP significantly reduced the CFU/mL count and showed cell compatibility. Conclusions The findings of this study demonstrate that the incorporation of HNT_CaOH 2 or HNT_β-TCP into resin-based experimental sealers promoted antimicrobial effects and gradual calcium release without impairing cytocompatibility or physicochemical properties of the sealers. Still, an adjustment to reach the minimal radiopacity established by ISO 6876 is needed. Clinical relevance The experimental resin-based sealers seemed to be an alternative for endodontics. The incorporation of calcium sources exerts promising antimicrobial effects while displaying low cell toxicity.