Objectives: to compare changes in surface microhardness of dentinal root (MSD) with two irrigation sequences (SI) using a Vickers microhardness test (VHN). Methods: 20 samples were prepared by longitudinal cutting of 10 unirradiculated human tooth. Two IS were prepared, a traditional one (5% NaOCl, saline 0,9%, 17% EDTA and saline 0,9%) and a modified one (traditional plus a final irrigation of 5% NaOCl), each irrigant isolated in a glass plate. In two groups of 10 samples (traditional IS and modified IS) 5 identations were performed by a Vickers microdurometer prior and after the IS immersion of the samples. The average of Vickers microhardness (VMT) of the samples was obtained and compared statistically. 0.05 P value. Results: A statistical difference of superficial microhardness was found among pre-irrigation (control) and post-irrigation in both protocols. Nonetheless, there was not a statistical difference among both protocols. Use of EDTA followed by NaOCl did not show a significant decrease of dentinal superficial microhardness. Conclusion: Use of NaOCl after EDTA did not show a significant decrease of dentinal superficial microhardness. Objectives: to compare changes in surface microhardness of dentinal root (MSD) with two irrigation sequences (SI) using a Vickers microhardness test (VHN).Methods: 20 samples were prepared by longitudinal cutting of 10 unirradiculated human tooth. Two IS were prepared, a traditional one (5% NaOCl, saline 0,9%, 17% EDTA and saline 0,9%) and a modified one (traditional plus a final irrigation of 5% NaOCl), each irrigant isolated in a glass plate. In two groups of 10 samples (traditional IS and modified IS) 5 identations were performed by a Vickers microdurometer prior and after the IS immersion of the samples. The average of Vickers microhardness (VMT) of the samples was obtained and compared statistically. 0.05 P value.Results: A statistical difference of superficial microhardness was found among pre-irrigation (control) and post-irrigation in both protocols. Nonetheless, there was not a statistical difference among both protocols. Use of EDTA followed by NaOCl did not show a significant decrease of dentinal superficial microhardness.Conclusion: Use of NaOCl after EDTA did not show a significant decrease of dentinal superficial microhardness.Objetivo: Comparar el cambio de microdureza superficial de la dentina radicular (MSD) ante dos secuencias de irrigación (SI) mediante prueba de microdureza Vickers (VHN).Materiales y Métodos: 10 dientes humanos unirradiculados se cortaron longitudinalmente para obtener 20 muestras. Se prepararon dos SI, una tradicional (NaOCl 5%, suero 0,9%, EDTA 17%, suero 0.9%) y una modificada (tradicional más irrigación final con NaOCl 5% + suero 0,9%), separando cada irrigante en una placa de vidrio. En dos grupos de 10 muestras (SI tradicional y SI modificada) se realizaron 5 identaciones con microdurómetro Vickers antes y después de sumergir las muestras en las SI. Se obtuvo el promedio de microdureza Vickers (VHN) de las muestras y se compararon estadísticamente. P valor de 0.05.Resultados: Se obtuvieron diferencias estadísticamente significativas entre la microdureza superficial dentinaria medida pre-irrigación (control) y post-irrigación en ambos protocolos, sin embargo, no se encontraron diferencias estadísticamente significativas entre ambos protocolos.Conclusión: Las SI -tanto tradicional como modificada -generan los mismos cambios en la microdureza superficial de la dentina radicular no presentando diferencias entre una y otra.