Endodontic infections play a significant role in the development and persistence of apical periodontitis. Eliminating or reducing microbial loads to a safe level remains a considerable challenge in root canal treatment (RCT), as bacteria and biofilms can become deeply embedded within dentine tubules or in anatomically complex areas.
This thesis of Victor Feliz Pedrinha investigated disinfection protocols at various stages of RCT, including irrigation solution regimens, intracanal medications, and alternative approaches such as the application of natural antimicrobial compounds, namely propolis (PRO) and copaiba oil-resin (COR), as well as the penetration of nanoparticles (NPs) into biofilms. The findings revealed that irrigation procedures using different chelating agents and further mechanical agitation strategies, achieved decontamination. Calcium hydroxide-based intracanal medications, formulated with various vehicles, reduced bacterial viability. PRO and COR did not alter cell metabolism concerning the cytokine levels of TGF-β1 and IL-6 and appeared to induce the release of AT1R, which may be linked to the proliferation periodontal ligament fibroblasts through specific interactions. PRO and COR exhibited low toxicity in Galleria mellonella larvae, indicating their safety at the tested concentrations. Additionally, both compounds demonstrated antimicrobial effects, suggesting their potential as complementary approaches in RCT to effectively reduce microbial loads. Bismuth sulfide NPs (Bi₂S₃), nucleated with different amounts of polyethyleneimine (PEI), demonstrated that 25 and 100 PEI-Bi₂S₃ NPs could infiltrate biofilms after 10 and 100 minutes of exposure.
This thesis outlines future perspectives and alternatives for enhancing disinfection in root canal treatments, potentially facilitating the healing of apical periodontitis and maintaining the homeostasis of the periapical system.
