Regeneration of periapical lesions post-endodontic treatment and periapical surgeries in experimental animals utilizing thermo-responsive nano-β-tricalcium phosphate/chitosan hydrogel: a proof of concept.

Using phosphate nanoparticles/polymeric hydrogels presents an interesting approach, especially concerning the reduced particle migration and enhanced biocompatibility. The current work aims to achieve a proof of concept for the development of a thermo-sensitive nano β-tricalcium phosphate (β-TCP)/chitosan (Cs)/glycerophosphate (Gl)/glyoxal (Gly) hydrogel to be applied in periapical surgeries post endodontic treatment. Physicochemical characterization using x-ray powder diffraction, Fourier transform infrared, TEM and SEM was performed. Bone formation efficiency of the achieved β-TCP/Cs/Gl/Gly hydrogel was followed. The composite gels were tested in vivo in dogs in comparison with the commercially available and surgically applied Klipdent-PL® up to three months. Radiographic examinations were performed. Histological evaluations were achieved through histomorphological criteria being apical cementum surface, bone tissue resorption, apical PDL thickness, the intensity of inflammatory reaction and osseous repair. The cytotoxicity results proved the safety of the developed hydrogel. The thermo-sensitive hydrogel possessed comparable enhanced biocompatibility with anti-inflammatory activity. New bone formation was clearly enhanced in the infected teeth. Therefore, it can be directly applied in specific non-invasive dental surgeries.