Table 3.

Incidence (%) of three canals in mandibular first premolars

Author(s)	Year	Incidence (%)
Vertucci [ 17 ]	1984	0.5
Pineda and Kuttler [ 10 ]	1972	0.9
Caliskan et al. [ 18 ]	1995	5.7
Zillich and Dawson [ 19 ]	1973	0.4
Yoshida et al.	2004	4.3
Trope et al. [ 33 ]	1986	African American 32.8 Caucasian 13.7