OBJECTIVES: This study aimed to evaluate the effect of different irrigation protocols on the viability and metabolism of stem cells from the apical papilla (SCAP) using a new in vitro protocol that simulates the clinical situation. MATERIALS AND METHODS: Forty-eight bovine dentin cylinders were obtained and prepared to simulate teeth with incomplete rhizogenesis, positioned under a three-dimensional (3D) culture of SCAPs to mimic the apical papilla. The cylinders were divided into four groups (n = 8) according to the irrigating solution: Control
NaOCl (Sodium hypochlorite 1%)
EDTA (17% ethylenediaminetetraacetic acid)
and NaOCl + EDTA. Subsequently, the viability (Live/Dead n = 2) and metabolism (Alamar Blue n = 6) of the cells were assessed (ISO 10993). Data were analyzed using Kruskal-Wallis and Dunn tests (p <
0.05). RESULTS: In the 1 to 3 days period, Control and EDTA had significantly higher increases in metabolism compared to NaOCl and NaOCl + EDTA (p <
0.05). In the 3- to 7-day period, metabolism significantly decreased in NaOCl + EDTA compared to EDTA (p <
0.05) but was similar to Control and NaOCl. Additionally, significant differences were observed within groups Control, EDTA, and NaOCl + EDTA across the two periods (p <
0.05). CONCLUSIONS: The tested in vitro model allows for the analysis of the response of SCAPs to different irrigating solutions, simulating the clinical situation. Sodium hypochlorite 1% demonstrated high cytotoxicity to SCAPs, whose effects were partially reversed by 17% EDTA. CLINICAL RELEVANE: The methodology developed provides a tool for future investigations, allowing for the assessment of new irrigants and techniques that may optimize tissue regeneration.