Evaluation of Necrotic, Edematous and Inflammatory Changes in Bone Marrow and Soft Tissue After Irrigation with Different Concentrations of NaOCl Solution: An Experimental Study in Rat Tibia.

objectiveWe aimed to investigate effects of different concentrations (0.5-5%) of Sodium Hypochlorite (NaOCl) solution on healthy tissues, and determine the optimal concentration that does not harm to tissue. MATERIALS AND

methods30 tibias of 15 male Wistar albino rats were used. The tibias were randomly divided into 5 groups (Salin, 0.5%, 1%, 2.5%, and 5% NaOCl). Tibias were reamed intramedullary, and irrigated with 20 ml of saline or increasing concentrations of (0.5-5%) NaOCl. The tibias were embedded in paraffin and the sections were stained with hematoxylin-eosin. All sections were assessed for edema, acute inflammation, or necrosis according to their density, in bone marrow and soft tissues.

resultsPairwise comparisons revealed that irrigation of tibia with saline or 0.5% NaOCl solutions was not statistically significant in terms of necrosis in the bone marrows (p=0.320). However, irrigation of rat tibia with saline caused less necrosis in the bone marrows compared to high concentrations (1%, 2.5%, and 5%) of NaOCl (saline and 1% NaOCl, p=0.017; saline and 2.5% NaOCl, p=0.0007; saline and 5% NaOCl, p=0.001).

conclusionAs an irrigation solution, the effects of 0.5% NaOCl are similar to those of saline in terms of edema, inflammation, and necrosis. There is a need for evaluation of necrosis for extended periods such as one week or one month by immunohistochemical methods and flow cytometry.