Fig. 3From: Variations of root and canal morphology of mandibular second molars in Chinese individuals: a cone-beam computed tomography studyClassification of C-shaped canal configuration [24]. C1: continuous C-shaped canal (a); C2: the canal shape represents a semicolon resulting from discontinuation of the C outline (b); C3: three (c) or two (d) separate canals; C4: only one round- or oval-shaped canal in the cross-section (e); C5: no canal lumen could be observed (f)Back to article page