(PR34) In Vivo Expression of Inflammatory and Neurotoxicity Biomarkers After Endodontic Sealer Exposure

Abstract: This study assessed the inflammatory and neurotoxic responses of four endodontic sealers: calcium silicate (EndoSequence BC Sealer), resin (Ah Plus Jet), zinc-oxide eugenol (ZOE, Pulp Canal Sealer), and silicone-based (GuttaFlow II) sealers on mouse mental nerve and trigeminal ganglia in vivo. Freshly prepared sealer was directly placed onto the left mental nerve of mice. Mice that underwent mental nerve transection were used as a positive control. Mental nerve and trigeminal ganglia tissues were collected 72-h after exposure. Gene expression of general inflammatory and neurotoxicity biomarkers were studied using RT2 Profiler PCR array. mRNA and protein expression of the classical sensory nerve injury markers Activating Transcription Factor 3 (ATF3), Neuropeptide Y (NPY), and Glial Fibrillary Acidic Protein (GFAP) were assessed by RTqPCR and immunohistochemistry. Evaluation of the general inflammatory response in the mental nerve showed the highest increase in inflammatory marker expression in the resin group, followed by similar expressions in the ZOE and calcium silicate groups. Silicone sealer had the lowest inflammatory marker expression (Resin >ZOE≅Calcium Silicate >Silicone). Evaluation of neurotoxicity marker expression in the trigeminal ganglion showed Resin≅ZOE >Calcium Silicate≅Silicone. Similarly, ATF3 and NPY mRNA and protein expression were highest in Resin >Calcium Silicate >Silicone≅ZOE. This study provides new information about toxicity of four endodontic sealers and showed that resin and ZOE sealer induce the highest inflammatory and neurotoxic response whereas silicone sealer induces the lowest response. Interestingly, calcium silicate induces a high inflammatory response but low neurotoxicity.