Table 1.

Incidence of three roots in the maxillary first premolars

Author	Year	Incidence (%)
Ingle	1965	2.0
Carns and Skidmore [ 3 ]	1973	6.0
Vertucci and Gegauff [ 5 ]	1978	4.0
Pecora et al. [ 22 ]	1991	2.5
Loh et al . [ 6 ]	1996	0.0
Kartal et al. [ 5 ]	1998	1.3
Chaparro et al .	1999	3.3