Assessing the Neurotoxicity of Endodontic Sealers

Abstract

Many times the relationship between dental materials and clinical outcomes is poorly understood because so little is known about the biocompatibility of materials and the biological pathways they may affect. In endodontics, there is no doubt a relationship between materials like canal sealers and the tissues they come in contact with, such as dental pulp, nerve, bone, and periodontal ligament—but how this relationship manifests in clinical outcomes such as post-operative pain is unknown. This study seeks to begin to uncover these pathways by examining the toxic effects of bioceramic, resin, zinc-oxide eugenol, and silicone-based endodontic sealers on cells and tissues. An in vitro model testing three cell types, human dental pulp stem cells (hDPSCs), neuron-like cells (NBs), and murine peripheral neurons (MPNs), exposed to sealers in a dose-response fashion was used to determine the relative toxicity of sealers. An in vitro model testing inflammatory and neurotoxicity biomarker gene expression after murine mental nerve exposure to sealer provided further evidence to the toxicities of these compounds and elucidated some of the biologic pathways they may trigger from the mental nerve to the trigeminal ganglia. Results from both models generally agree that AH Plus is the most toxic and that GuttaFlow 2 exhibits nearly no toxicity, but more importantly the results of this study show how in vitro modeling can complement more complex in vivo modeling in biomaterials science.