Fig. 5

Histological characteristics of the left mandibular first molar tooth (36). (a) An overview micrograph of the longitudinal section of the tooth shows that the pulp chamber is almost completely obliterated by the CMD. Note remnants of the pulp located above the CMD and a root-like structure projecting from the cervical area. Higher-magnification micrographs (b) show the fibrous appearance of the coronal pulp tissue and (c) amorphous tissue resembling tertiary dentin at the pulp periphery, i.e., at the border between the CMD and occlusal dentin (yellow double-sided arrow), with individual cells residing in the lacunae resembling chondrocytes (black arrow). (d) Numerous chondrocyte-like cells are residing in the thin dentinal wall. In the heterogeneous structure of the CMD, note (e, f) connective tissue canals containing blood vessels (asterisks), (g) green-stained collagen fibers; below the CMD, note (h) abnormal dentin and tissue resembling cellular cementum, with connective tissue canals and round-to-ovoid structures (arrows) of concentrically arranged collagen fibers and locked-in cells. (i) Round-to-ovoid structures are also present in the root-like extension. CMD: cervical mineralized diaphragm; d: dentin; p: pulp. (a-f and h-i): HE; (g): Masson-Goldner staining