[How to predict the presence of three-rooted maxillary premolars].

Sixty extracted maxillary premolars, 55 firsts and five seconds, were classified into three categories according to the beginning of their trifurcation. The mesiodistal dimensions of the buccal roots, at different levels, were compared with the mesiodistal diameter at the cervix. Among all teeth examined, the proximal profiles of the roots were parallel in the two cervical thirds, or the mesiodistal dimension at the middle third or apical third was greater than this at the cervix. If these observations are visualized on the radiograph, the dentist can presume that these teeth have three roots.