Fig. 6

Histological details of the longitudinal section BSPG AS I 1656. Images in a and b are both seen in polarized light with lambda compensator. a Complete view of the sectioned tooth. At the root the orthodentine (blue colours) is embedded in vascularised pulpal and external cellular cementum of the osteocementum type. Note the differences in structural orientation between the ordered upper pulpal cementum (yellow and blue colours) and the irregular external and basal root cementum (pink colours). At the cementum–dentine junction, a thin layer of acellular cementum is visible (yellow colour). b Close-up of the orthodentine pillar. Coarse parallel Sharpey’s fibres are visible in the external cellular osteocementum. The orthodentine shows a weak banding often obscured by dark dentine tubules. The pulp cavity is filled with sparitic calcite minerals. AC acellular cementum, CC cellular cementum, DT dentine tubules, GT granular layer of Tomes, OD orthodentine, P pulp cavity, SC sparitic calcite, ShF Sharpey’s fibres