Aris Zhu

Aris Zhu, Hamilton High School, Chandler, Arizona

CASA: A Novel Intracanal Medicament for Endodontic Infections

Currently, calcium hydroxide (CaOH) is used as an intracanal medicament to treat root canal infections. However, CaOH paste is ineffective against persistent bacteria Enterococcus faecalis and fungus Candida albicans, which may give rise to health conditions including heart valve infection or periodontitis, respectively. Furthermore, the high pH of CaOH causes dental pulp necrosis, which delays tissue healing. To improve antimicrobial properties and limit cytotoxicity, salicylic acid was added in a 3.7:1 mass ratio to create a neutral paste to disinfect the canal. Using a modified disk diffusion antibiotic sensitivity test, CASA was plated with common endodontic microbes in a root canal infection to determine its antimicrobial activity. CASA produced larger zones of inhibition than CaOH for all species tested, indicating that CASA is the more efficacious antimicrobial agent. Notably, CASA yielded an inhibition zone 2.76 times that of CaOH in the presence of E. faecalis. Cytotoxicity studies and observation of dental pulp stem cells (DPSCs) under fluorescence microscopy indicated a high tolerance for DPSCs for CASA with a measured IC50 of 0.25 mg/ml, a far higher dose than tissue would be exposed to during standard treatment. Viability staining with E. faecalis and C. albicans confirmed the antimicrobial properties of CASA precipitate. CASA was found to be dosage dependent with increasing concentration resulting in greater bacterial lethality against S. aureus and E. coli. Because CASA was found to have greater antimicrobial effect and biocompatibility to dental pulp, CASA has the potential to replace CaOH in treatment for recurrent root canal infections.

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