Figure 2From: Root resorption, treatment time and extraction rate during orthodontic treatment with self-ligating and conventional brackets External apical root resorption (EARR) stages according to Malmgren et al. 1 irregular root contour, 2 EARR <2 mm of root length, 3 EARR >2 mm to 1/3 of root length, 4 EARR >1/3 of root length. Back to article page