Table 2.

Incidence (%) of three canals in maxillary first premolars

Author	Year	Incidence (%)
Pineda and Kuttler [ 10 ]	1972	0.5
Green	1973	0.0
Carns and Skidmore [ 3 ]	1973	6.0
Pecora et al. [ 9 ]	1991	2.5
Kartal et al. [ 5 ]	1998	1.7