Evaluation of antibacterial effect of two different intracanal medicaments on bacterial load in infected mature permanent teeth and their effect on post-operative pain level.

Microorganisms within the root canal system exist as complex, multispecies biofilms made up of microcolonies that adhere permanently to each other and to surfaces such as dentin. The characteristics of these biofilms-including their composition, thickness, and location-vary according to environmental conditions like nutrient availability, pH, oxygen levels, and exposure to the oral cavity. Endodontic treatment aims to save teeth with damaged pulp tissue, as maintaining natural teeth is essential for proper oral function and overall health. Understanding the specific microorganisms involved in endodontic infections is crucial for explaining disease progression and selecting the most effective treatment strategies.

Because of the intricate anatomy of the root canal system, both mechanical instrumentation and chemical irrigation are required to reduce microbial load. However, chemo-mechanical debridement alone is often insufficient, allowing some bacteria to persist within the canal. As a result, antimicrobial intracanal medicaments have been introduced to enhance disinfection. Although several medicaments are currently used, many show limitations such as microbial resistance or an inability to simultaneously control intracanal infection and periapical inflammation. Additionally, antimicrobial agents may interact with the immune system, potentially suppressing or stimulating immune responses.

Enterococci, particularly *Enterococcus faecalis*, are frequently associated with persistent endodontic infections due to their resistance to treatment and ability to survive harsh conditions. Calcium hydroxide, a material introduced to dentistry in the early 20th century, is widely used as an intracanal medicament but has limited effectiveness against certain bacteria such as *E. faecalis*. Recent interest has focused on nanoparticles, which range from 1 to 100 nm in size and possess unique antimicrobial properties with reduced resistance. Among these, chitosan nanoparticles-derived from chitin found in crustacean exoskeletons-have gained attention for their biocompatibility and antibacterial effects. Effective intracanal medicaments are also important in reducing postoperative pain, which is commonly linked to bacterial irritation following endodontic treatment.

Inclusion Criteria:

• free medical history,
• mature infected permanent single rooted teeth diagnosed clinically and radiographically with adequate coronal structure for proper isolation, temporization and restoration.

Exclusion Criteria:

• Patients who are not included in the age range of the study or having a systemic condition.
• Teeth with severe fractures or resorption or periodontally compromised.