Morphology of pulp horns and root canals in maxillary cheek teeth. Arabic numerals (1 to 8): Pulp horns. Roman numerals (I to IV): Root canals. Colours indicate separate pulp compartments. (a) 3D models of the pulp cavity. Inserted planes p1 to p4 render the position of selected 2D μCT images, coloured planes indicate locations of connections. Sections (p1-p4) demonstrate cross-sectional shape and size of pulp horns and root canals. Dark grey: Pulp tissue; light grey: Dentine and cementum; white: Enamel; rbm = bucco-mesial root; rbd = bucco-distal root; rp = palatal root. No segmentation (Triadan 211, 2 years): A wide common pulp chamber (*) connects all pulp horns. Root canals are seen at early stage of development. Partial segmentation (Triadan 107, 5 years): Three separate pulp compartments are present. Root canals I and III contribute both to the branching pulp horns 1, 3 and 5. Root canal II solely contributes to pulp horn 2. Root canal IV solely contributes to pulp horn 4. Green ellipse: Pulp horn 2 is split up into a main and a delicate accessory branch. Maximal segmentation (Triadan 107, 8 years): Four solitary pulp compartments are present. Root canal I solely contributes to the coalesced pulp horns 1 and 3. Root canals II, III and IV solely contribute to pulp horns 2, 5 and 4, respectively. Green ellipse (a, p1): Pulp horn 1 is split up into a main distal and an accessory mesial branch.