Table 1 Number and frequency of roots in mandibular second molars by gender and age

1-O-shaped root^a

14 (2.33)

6 (1.0)

7 (1.75)

4 (1.81)

3 (1.66)

6 (2.3)

–

20 (1.66)

1-C-shaped root^b

255 (42.5)*

172 (28.6)*

155 (38.75)^§

64 (29.1)^§

58 (32.2)^§

97 (37.3)^§

53 (37.8)^§

427 (35.6)

1-O-C-shaped root^c

1 (0.16)

4 (0.66)

1 (0.25)

4 (1.81)

–

–

–

5 (0.41)

C + ML root^d

3 (0.5)

1 (0.16)

2 (0.5)

–

1 (0.55)

1 (0.38)

–

4 (0.33)

C + DL root^e

1 (0.16)

2 (0.33)

–

–

1 (0.55)

2 (0.76)

–

3 (0.25)

C + L root^f

3 (0.5)

–

2 (0.5)

–

–

1 (0.38)

–

3 (0.25)

Two roots^g

321 (53.5)**

412 (68.6)**

232 (58.0)^§§

146 (63.6)^§§

116 (64.4)^§§

152 (58.4)^§§

87 (62.1)^§§

733 (61.0)

Three roots^h

–

2 (0.33)

1 (0.25)

–

–

1 (0.38)

–

2 (0.16)

Four rootsⁱ

2 (0.33)

1 (0.16)

–

2 (0.9)

1 (0.55)

–

–

3 (0.25)