Fig. 4

Histological characteristics of the right maxillary first molar (16). (a) An overview micrograph of the longitudinal section of the tooth shows a discontinuous cervical mineralized diaphragm (CMD) in the area of the pulp chamber and a narrow coronal pulp positioned above and interspersed between the regions occupied by the CMD. A smaller area occupied by radicular pulp is also apparent. Higher-magnification micrographs marked with rectangles (b) show the course of the dentinal tubules in the coronal dentin interspersed between the CMD, (c) amorphous tissue at the border between the CMD and dentin (yellow double-sided arrow) and the connective tissue canal containing blood vessels (yellow arrow). This connective tissue exhibits pale staining with toluidine blue, whereas the surrounding tissue consists of globules and a toluidine blue-positive interglobular matrix. (d) CMD consisting of globules and interglobular matrix. At the border with dentin (e), there are enlarged chondrocyte-like cells residing in the lacunae and surrounded by the alcian blue-positive matrix, suggestive of cartilage proteoglycans. (f) Tissue below the CMD resembles cellular cementum; note the ingrowth of the connective tissue canal containing blood vessels (yellow arrow). (g) Single or (h) multiple denticle-like structures are present below the CMD and (I) within the root canal. Denticle-like structures are either (j) partly or (k) completely incorporated into the dentin. Cells present within the central area (asterisk) are suggestive of an immature denticle (g). A layer of columnar odontoblasts that should surround the outer surface of intrapulpal stones is not obvious. cc: cellular cementum; CMD: cervical mineralized diaphragm; d: dentin; p: pulp. (a, b, c, g, h, i and k): toluidine blue (pH 7.2); (d, f, j): HE; (e): alcian blue (pH 2.5)