In vitro study of root canal anatomy of maxillary second premolars.

The external anatomy of 435 maxillary second premolars and the internal anatomy of 300 of these premolars were studied in vitro. For the study of the internal anatomy, the teeth were decalcified and cleared. One canal was found in 67.3% of the second premolars, two canals in 32.4% and three canals in 0.3% of these premolars. A total of 90.3% had one root and 9.7% two roots. A predominance of root curvature toward the distal was found in maxillary second premolars with both one or two roots.