Fig. 2

Odontometric measurement of the DB and DL roots of three-rooted deciduous mandibular second molars (DMSMs) and a three-rooted permanent mandibular first molar (PMFM) in the CBCT images (from the adjusted proximal view). a L2 is the vertical length of the DL root; L3 is the level of the distal root furcation (a DMSM). b Angle α is the spreading angle of DL root, and angle β is the spreading angle of DB root (a DMSM). c Angle α is the curvature angle of the DL root measured by Schneider’s method (a DMSM). d Measurement of the angle of root curvature of the DL and DB root by Schneider’s method (a PMFM)