Table 4.

The curvature of root canal on its dominantly curved side and gring. *p < 0.05, independent samples t test

	Average curvature $\left[\overline{X}\pm S\left({}^{\circ }\right)\right]$	Curvature degree [n, (%)]
Dominantly curved direction		Moderately curved (10–25°)	Severely curved (> 25°)
Mesiodistal	18.06 ± 10.39	494 (78.4)	136 (21.6)
Buccopalatal	21.36 ± 8.62a	321 (71.7)	127 (28.3)

^aSignificant difference, p = 0.000000 < 0.05