The institutional review board of the Faculty od Odontology Tijuana México approved the study protocol and all the participants were treated in accordance with the Helsinki Declaration (www.cirp.org/library/ethics/helsinki). The study started in February 2016 and ended in February 2017. The main inclusion criteria were: a) A diagnosis of pulpitis confirmed by positive response to hot and cold tests and b) Clinical and radiographic evidence of symptomatic apical periodontitis. It was determined based on the clinical symptoms severe preoperative pain (VAS > 60) and severe percussion pain (VAS > 60). Confirmed by positive response to hot and cold tests. Thermal pulp testing was performed by the author, and radiographic interpretation was verified by one certified oral surgeon.