Effect of Chitosan Nanoparticles as an Irrigant in Regenerative Endodontic Therapy of Necrotic Immature Permanent Teeth: An In Vivo Dog Model Study

Background: The aim of this study was to investigate the effect of 2% chitosan nanoparticles (NPs) as an irrigating solution during pulp revascularization of immature dog teeth using histological and histomorphometric analyses. Materials and Methods: Pulp necrosis and periapical pathosis were induced in 52 incompletely formed roots in four dogs (6-8 months age). These teeth were randomly allocated to Group I (n = 20; irrigation with NaOCl + EDTA), Group II (n = 20; irrigation with NaOCl + chitosan NPs), DAP was used as a medication in both groups. Positive control (6 roots): teeth with induced periapical infections, no treatment procedure, and left open. Negative control (6 roots): teeth that were left untreated for the normal maturation process. Each experimental group was subdivided into 2 divisions in accordance with the post-treatment evaluation periods (1- 3 months). The experimental teeth were re-entered following the infection period and disinfected using the assigned irrigation and medication protocol, and the access cavities were sealed. After the evaluation period, medication was removed, and blood clot formation was created through over-instrumentation. Mineral trioxide aggregate (MTA) was applied, followed by glass ionomer restoration (GIC). Results: At both 1 and 3 months, Group II demonstrated significantly superior histological organization and higher collagen-positive area percentages compared with Group I (p < 0.01), while the negative control showed the highest values and the positive control the lowest. Conclusion: Irrigation with 2% chitosan NPs significantly improved regenerative outcomes compared with the conventional NaOCl/EDTA protocol in immature canine teeth.