Exploring the multifaceted biological effects of phenolic acids for application in endodontics

Considering the presence of a complex biofilm and persistent inflammation in infected dental root canals, this study evaluated the cytotoxicity and inhibitory effect of phenolic acids on pro-inflammatory gene expression and multispecies biofilms for endodontic applications. First, cinnamic acid (CI) and caffeic acid (CA) were screened based on their inhibitory activity on oral bacteria and toxicity on fibroblasts and macrophages by colorimetric assays. Then, their effects on mRNA levels of pro-inflammatory markers were determined by qPCR in macrophages exposed to LPS. In addition, these compounds were also tested against dual-species and multispecies biofilms in root canals by scanning and confocal microscopy. CI and CA exhibited bactericidal effects against tested bacteria. Both compounds significantly reduced pro-inflammatory markers in a dose-dependent manner. CI and CA eliminated dual-species biofilms and significantly decreased multispecies biofilms. In summary, cinnamic acid and caffeic acid exhibited multifaceted biological activities and may be indicated as medicaments for endodontically compromised teeth.