Evaluation of Antimicrobial Efficacy and Adaptability to Root Canal Dentin of Bioceramic Sealer Containing Nanoparticles (In-vitro Study)

The main purpose of endodontic therapy is to clean and shape the root canals. This is done by means of instruments and chemical irrigants in order to effectively control the pulpal and periapical infection. That chemomechanical preparation aims to reduce the microorganisms count but cannot completely eliminate it. This is mainly due to (i) anatomical complexity and access limitations (ii) incompetent chemomechanical preparations leaving surfaces untouched (iii) ineffectual irrigation. Besides, despite an accurate chemomechanical preparation, infection may persist in 20-33% of cases, even if intracanal medicament is used.

Treatment failure may also occur due to microleakage, which occurs due to interfacial gaps between the gutta-percha and the sealer, the sealer and the dentin, or through voids within the sealer. Fifty eight percent of treatment failures happen due to incomplete obturation and that's why, hermetic seal is the main factor associated with the success of root canal treatment . Therefore, disinfection, gap-free, three dimensional obturation are the main requisites for treatment standards in endodontics.

Another reason for treatment failure is presence of persisting bacteria. Enterococcus faecalis is a resistant bacterium commonly retrieved from obturated root canals with post treatment disease (apical periodontitis). This pathogen is believed to be highly virulent; it can invade dentinal tubules, adhere, overcome environmental challenges and form biofilm.. Besides, it can resist intracanal disinfectants and medicaments. Therefore, the best approach to resolve this is by using a sealer with broad spectrum antibacterial action.

Ideal root-canal sealer should be able to kill microorganisms on direct contact on the dentinal walls and those present deep inside the dentinal root canals. That means that it should be able to diffuse inside the dentinal tubules to entomb and kill surviving bacteria. Besides, it should be capable of perfectly sealing the prepared canal to block any space and nutrients needed for bacterial growth. Finally, endodontic sealers that retain flowability and antimicrobial properties may help eliminate microorganisms in the root canal system.

Dspite the fact that most sealers have antibacterial constituents, their antibacterial activity is eventually lost after setting. Besides, even if it doesn't, these constituents have to be liberated from the set sealer matrix to fulfill their function. Then again, their release would be accompanied by disintegration of the sealer, interfacial gaps and later on bacterial recolonization.