Characterisation of pulpal responses to bacterial challenge and novel sntimicrobials for management of bacterial contamination of infected pulps.

Abstract

Dental pain from pulpal infection and inflammation are the common cause of dental emergencies. Therefore, evaluation of modalities to treat them would be beneficial. This work aims to characterise and validate the previously developed ex vivo pulp infection model and make it reliable and reproducible in terms of quantifying cell viability, area of bacterial colonisation and expression of inflammatory markers. The method developed and used in this work demonstrated that SAG infection reduced cell viability and IL-10 levels. SAG infection also Increased area of SAG colonisation of pulp,expression of IL-β, TNF-a and IL-18 in a time depended manner compared to uninfected control pulp. These findings were consistent with clinical observations, making it a reliable model for the observed characteristics. There were differences in the response to two SAG strains, with similar overall trends, but with greater response to S. constellatus.Differences in response to the two strains was confirmed by evaluating the effect of the SAG supernatants using the model. The response observed confirmed the deleterious effects of the supernatant on cell viability, and increase in expression of inflammatory markers, with a greater response of pulp observed to S. constellatus. Analysing the supernatants of SAG strains revealed the difference could be due to hyaluronidase produced by S. constellatus.Triclosan’s anti-microbial and anti-inflammatory effect in the treatment of pulpal infection was demonstrated using the SAG model through increased cell viability, reduced area of colonisation and inflammatory marker expression levels form triclosan treatment. Triclosan showed no anti-hyaluronisase activity.A poly-microbial infection model was developed with E. faecalis and S. anginosus on tooth slices. It was observed that E. faecalis perpetuated S. anginosus growth in mixed culture and caused greater cell-death compared to S. anginosus mono-infection. The proportion of E.faecalis and its affinity to blood vessels could influence the response of the model