Ion release characteristics, precipitate formation and sealing ability of a phosphate glass–polycaprolactone-based composite for use as a root canal obturation material

The filling material used to obturate root canal systems during the common dental procedure, root canal treatment, has popularly involved gutta-percha (GP) in one of its many forms for almost a 100 years. An optimal root filling material should provide a predictable seal, inhibit or kill residual bacteria, prevent re-contamination and facilitate periapical healing. Although the goal of obturation is stated as the creation of a “seal”, its precise role still remains elusive and the seal offered suspect. The primary goal of the study was to develop a novel polycaprolactone/phosphate glass composite deliverable as a root filling and capable of releasing ionic species to enable a predictable seal in an aqueous environment. Different compositions of polycaprolactone–iron phosphate glass (Fe2O3 1, 3 and 5 mol%) composites were produced and delivered into an ex vivo root canal model. Standardized root canals were prepared in extracted human teeth. The teeth were examined for root filling adaptation and precipitate formation (SEM), ion release (Na+, Ca2+, PO43−, P2O74−, P3O93−, and P5O105−), and sealing ability. The experiments were controlled with teeth obturated with contemporary GP and a conventional zinc-oxide/eugenol sealer. Adaptation of the experimental material was statistically significantly better than the GP control groups. Precipitate formation was noted in some specimens but all released various ionic species in an inverse proportion to the iron oxide concentration. The experimental material exhibited significantly (P < 0.001) less leakage after 7 days immersion in saline compared with those not immersed, or the control GP group. PCL–phosphate glass composites showed good potential as a root filling material capable of producing a seal in an aqueous environment without a sealer.