Page 89 - My FlipBook

THE DENTAL PULP. 87

osteoblasts are filled with minute, glistening globules. As the growth
continues, these cells appear to fuse into the cementum already formed.
At the neck of the tooth outside this layer, which is forming the matrix
of the cementum, a row of cells is seen which, according to Rollet, re-
sembles an epithelium. They are really new osteoblasts or cemento-
blasts filled with the minute glistening bodies. Just exterior to these
cells, roundish nucleated cells with innumerable processes are seen
slightly resembling a stellate reticulum. Outside of these is a con-
nective-tissue layer which will become the periosteum. This slight
amount of stellate tissue is probably what has been called the special
cement organ. Across the developing matrix of the cement are found
numerous connective-tissue fibers seen and described by Sharpey and
named after him Sharpey's fibers. They become calcified within the
matrix. As the cementum grows thicker we find infolded within its
substance nucleated bodies which appear to be connective-tissue cells.
They apjiear larger than the osteoblasts and are forming the regular
lacuuffi of the cementum. Their function is to give nourishment to
the matrix of the cementum, anastomosing with one another by means
of many fine canals, many of which run in the direction of the termi-
nation of the dentinal canals as though connecting with them. They
are not as regular as those in true bone, and are often very much larger.
The processes of these cells anastomose with the dentinal canals through
the interglobular spaces of the so-called granular layer of Tomes. Thus
the matrix of the cementum is formed from the cementoblasts which
have become filled with calcific material from the blood supply every-
where near. They rest against already formed dentin and become
merged into a layer of calco-globulin, which in turn becomes calcified
into the first layer of cementum. Layer after layer is formed, and
this gives to the cement the peculiar laminated appearance so often
seen in it.
The Dental Pulp.

The tooth pulp is that which remains of the dentin germ after cal-
cification is completed. It is very generally but erroneously called the
" nerve." In the young tooth it is composed of connective-tissue matrix
which contains the nerves and vessels supplying the dentin. These
are more numerous near the odontoblastic layer, the nerve fibers appear-
ing to terminate here. The odontoblasts cover the surface of -pulp like
an epithelium. Just Avithin these is a layer of cells consisting of a
comparatively pale and transparent zone, and this has been called the
basal layer of Weil. It is described as consisting of fine connective-
tissue fibrils which communicate with the processes of the odontoblasts.
Von Ebner doubts the existence of this layer, as does Rose.