Expression of NaV-1.7, TNF-α and HSP-70 in experimental flare-up post-extirpated dental pulp tissue through a neuroimmunological approach

Background: Dental caries continue to represent a major problem which, if left untreated, will cause irreversible pulpitis. Root canal treatment constitutes one potential treatment intended to preserve teeth afflicted with irreversible pulpitis. During root canal treatment, pain or swelling, referred to as flare-ups, can occur at any point in the process. Aim: To analyze the molecular aspect of the phenomenon of flare-up in vital dental pulp tissue following mechanical and bacterial trauma (extirpation and lipopolysaccharide [LPS] induction respectively) through a neurological approach, based on the expression of NaV-1.7 in neuron cells, and HSP-70, TNF-α in macrophage cells. Method: This laboratory experimental study was conducted using 15 Spraque Dawley rats as subjects which were divided into three groups of five subjects: a control group, a pulp tissue extirpation group and an LPS induction followed by extirpation of pulp tissue group. Test samples were collected from the apical field of the mandibular incisor and subsequently examined using immunohistochemical methods. Results: There were significant differences in NaV1.7, HSP70 and TNFα expression between the treatment groups. While a marked increase in the expression of HSP70 occurred, both Nav1.7, and TNFα expression decreased significantly. Conclusion: Extirpating the dental pulp tissue will induce a more pronounced flare-up response from the molecules of the pulp tissue in vital teeth than those in inflamed vital pulp tissue.