Root Canal Filling Pastes Cytotoxicity Through Root Canal Simulating Model

Objectives: The inexistence of an ideal root canal filling material for the primary teeth is observed in the literature. The aim of this study was to evaluate comparatively the cytotoxicity of a novel calcium hydroxide (NCH) (SSWHite, RJ, Brazil) based root canal filling paste with three different resorbable materials, through a root canal simulating model.
Methods: The comparative pastes were non-reinforced zinc-oxide and eugenol, iodoform with calcium hydroxide (Vitapex^®), zinc-oxide/eugenol, iodoform and calcium hydroxide (Endoflas^®) and calcium hydroxide (Calcicur^®). Pippete tips (5-10μL) (n=3) with a final diameter compatible to the apical diameter of a #45 K file, were filled with 0,037g of each paste. Extracts of the pastes were prepared by exposing the pippete tips to culture medium for 24hs. Primary human osteoblast-like cells were exposed to extracts and positive, negative and experimental controls for 24 h, at 37°C with 5% CO₂. Cell viability was analyzed sequentially through a multi-parametric approach (XTT, NR, CVDE). The pastes cytotoxic effects were also assessed through the XTT assay (n=5) using the ISO 10993-5 (2009) 0.2g to 1ml material/vehicle ratio. Cytotoxicity was rated based on cell viability relative to the experimental control.
Results: When the pastes were evaluated through the model and the XTT assay, a slight cytotoxic effect (CE) was observed for Calcicur^®, NCH, Endoflas^® and ZOE. Vitapex^® showed moderate CE. Through the NR and CVDE assays, the CE was slight for Calcicur^®, Endoflas^® and ZOE, moderate for Vitapex^® and NCH. According to the ISO ratio, the Calcicur^® paste showed moderate CE, while the others materials were considered as strongly cytotoxic.
Conclusions: It was concluded that the NCH showed slight and moderate CE when evaluated through the root canal model and strong CE through the ISO ratio. Furthermore, all materials presented lower CE results through the model compared to those obtained through the ISO ratio.