Number of roots and canals in maxillary first premolars: study of an Andalusian population

A study of 150 extracted maxillary first premolars from citizens of Seville , Andalusia, southern Spain, revealed 60 teeth with one root (40.0%), 85 te eth with two roots (56.7%) and five teeth with three roots (3.3%). The dist ribution of root canal shapes in the sample showed that all teeth with two or three roots had type I root canals (each canal had one apical foramen). Conversely, most of the single-rooted maxillary first premolars had root ca nal shape type II (two canals converging in the same apical foramen). Only 1.3% of the teeth had a unique orifice in the pulp chamber and only one roo t canal. These results emphasized the importance of good knowledge of the r oot canal morphology and the need for a careful radiographic examination as part of competent root canal therapy of maxillary first premolars.