Endodontic treatment failures, often attributed to Enterococcus faecalis, present a considerable obstacle in dental care. While calcium hydroxide remains the predominant medicament, it lacks sufficient antimicrobial efficiency against E. faecalis, is harmful to the surrounding tissue, and its injectability is poor. In contrast, salicylic acid has not been commonly used in endodontic treatments, yet it has demonstrated high efficacy against E. faecalis as of its low PH, it will cause demineralization to the dentin surfaces. This study exhibits the potential of combining calcium hydroxide and salicylic acid (CASA) encapsulated in reverse thermoresponsive hydrogels, based on methacrylated Pluronic F127 (F127DMA), as an injectable and retrievable intracanal medicament with strong antibacterial efficacy and controlled drug release.
Various ratios of calcium hydroxide to salicylic acid were tested, and a 1:6 ratio was found to offer optimal water solubility. This mixture was subsequently incorporated into F127-DMA, without significantly affecting the gelation properties, and UV-crosslinked with LAP. FT-IR and RAMAN spectroscopy confirmed cocrystallization and the formation of calcium salicylate. The optimized formulation achieved a neutral pH (~6), a high crosslinking efficiency and an adequate swelling ratio. Alos, CASA reduced the contact angle of F127DMA significantly, enhancing the absorption of inflammatory exudates.
Encapsulation of the CASA mixture within the hydrogel significantly reduced the viscosity of the original paste, facilitating its injection into root canal models and proving to be easily retrievable. Liquid suspension assays demonstrated that F127DMA containing just 5% CASA was effective against E. faecalis. Bovine anterior tooth slices were infected with E. faecalis and allowed to form mature biofilms. CFU analysis was conducted to assess bacterial viability and CASA gels showed reduction in bacterial count compared to controls.
The superior rheological properties of the F127DMA-CASA hydrogel, which permit injectability and retrievability, together with superior antibacterial properties, and regenerative potential make it a promising new alternative to standard intracanal treatments.

Stephen Walker

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