The distance of the orifice canals in the First and second maxillary molars wich has second mesiobuccal canal: In our study, the average distance between the orifice canals MB1 andMB2 in the First maxillary molars is nearly 2.28 mm, which is equivalent to the results of other authors: the MB2 orifice is located 1 to 3 mm from the MB1 orifice, in the bucal-langualdirection, on the connection of the MB1 and the langualcanals.