[A clinical observation on 218 maxillary first molars canal system]

218 maxillary first molars were observed during clinical endodontic therapy for canal system;the number of canal,working length,and the location at the floor of each orifice.As to the patients;97 are male,121 are female,age from 13 to 76.Results shown that each mesiobuccal root of 28 molars(12.84%) included two canals,there was no significant difference in canal number in the mesiobuccal root of maxillary first molar were decreased with the age.The suggestion was made the notice for the complicated canal system,improving the shape of access,holding the method to find out the second canal in the mesiobuccal root could avoid missing canal on treating maxillary first molars endodontically. The resinifying therapy seems to raise successful rate for treating molar with complicated canal system.