Root canal morphology of the maxillary first premolar.

Four hundred maxillary first premolars were decalcified, injected with dye, cleared, and studied. The canal configurations were categorized as: 26% had one canal, 69% had two canals, and 5% had three canals at the apex. The relationship of canal configuration to number of roots per tooth was determined. Of the canals studied, 49.5% had lateral canals. They occured equally in all types of canals, were located mainly in the apical region, and exited from the main canal mostly in a palatal direction. Also, 11% of these canals extended from the floor of the pulp chamber to the furcation area. An accurate knowledge of the morphology of the pulp cavity is essential before endodontic procedure can be approached rationally. The frequency with which root canals unite should be considered during enlargement and filing procedures. The dentist also should be aware of the possible existence of bifurcated and double canals if root canal therapy should unexplainbly fail. A knowledge of these variations will assist the dentist in reaching conclusions when diagnosing and treating endodontic cases.