Abstract
Introduction: This clinical study will be conducted to compare the effectiveness of two rotary systems Hyflex CM (Coltene-Whaledent, Allstetten, Switzerland) and Protaper Next (Dentsply Maillefer, Ballaigues, Switzerland) in removing endotoxins and cultivable bacteria from primarily infected root canals. Methods: Twenty-four primarily infected root canals of maxillary molars will be selec…