The Bourbon news. [volume] (Paris, Ky.) 1895-19??, 1909-05-25
TEETH AS THEY GROW
The Way Nature Forms and Fixes
Them In the Gums.
THEY ARE NOT MADE OF BONE.

Them Fer Varying Uses.
Familiar to everybody as are the
teeth, few persons, save those who
have dipped into their history viewed
from the scientific side, can form al
adequate idea regarding their true ma
ture. If the man in the street were
asked to construct a classified list OF
his bodily belongings he would almost
certainly place teeth in the section
which included the bones. There ap.
pears reason for his choice. Teeth are
hard and bOnelike in structure, and
they are fixed in the jaws. These facts
would seem on the face of things to
justify the inclusion of the teeth il
the list of skeletal structures. This
view Of the teeth, however, is readily
proved to be incorrect. We have only
to appeal to natures way of making a
toOth-in other words, to study it's de-
/ velOpment-to assure ourselves that
teeth are not bones at all, but struc-
lures Of a very different kind.
The first Indication Of tooth forma-
ton begins in very early life with the
formation Of a groove in the gum, or
mucous mcmbrene lining the raouth.
This furrov is the birthplace e The
teeth. From the groove arise as many
little projec items CT the gum as there
are to be teeth Each projection we
call papilla.
Now this little body contains a plen-
tiful supply OF blood vessels, destined
to bring to it the raw material blood
out Of which not teeth alone, but all
other organs, tissues and secretions,
are manufactured. The papilla, be-
sides, is composed of and particularly
invested with living cells Of special
kind. These cells are to be regarded
as the workmen which fabricate the
tooth. The material specially required
for tooth formation consists Of COM
pounds Of lime associated with other
substances.
Around the papilla and upon it, as
On a mold, the hard material of the
tooth is deposited. 1t is elaborated
into a substance which, under the
microscope, shows a special structure
Of its own, differing widely from that
which is represented in bone The
great bulk Of a tooth consists of ivory
or dentine, as it is also called. This
is q dense, hard substance which
shows a texture composed Of an in
finite variety of microscopic tubules.
But at the crown Of the tooth es-
pecially we meet with a layer Of diff
ferent kind and of still harder con-
sistence. This is the enamel, which
ranks as the hardest substance in the
body. It's position on the crown Of
the tooth bears a relation to the resist
8nce to wear and tear the tooth is in
tended to exhibit, the softer ivory be-
ing thus protected from the obvious
results of the process of attrition.
Thus on the papilla, as on a living
mold, the tooth is formed, it's sub
stance coming to cover, as in an en-
velope, the little projection itself.
Long before the tooth, however. is
completed the groove in the gum has
become partitioned off into a series Of
sacs or compartments. The furrow
itself becomes converted into a tube
by the upward growth and union of
its edges in the middle line Then
succeeds division into sacs, in each Of
which a papilla is present and in each
of which a developing tooth is con-
tanned.
If the hard materials of the tooth be
found around the papilla we discover
thus that the tooth is a hollow and not
solid structure, for the pulp inside
every tooth, q substance richly sup
piled with nerves and blood vessels,
really represents the papilla of the
early stages. The toOth's nourishment
is thus duly provided for, since proc
esses Of the pulp pass into the minute
tubules OF the ivory and so contribute
to the maintenance Of the vitality of
the organ.
When the tooth is completed within
its sac, all that. remains is for it to ap-
pear in the jaw, in which provision
has been made for its fixation. \
tooth "cuts'' the gum when through
upward pressure on the sac it bursts
through its Investment and takes the
place nature has mapped out for it in
the armamentarium of the mouth.
Now. in all this history there is no
hint given Us Of any connection be
tween bone formation and tooth devcl-
oprccnt save indeed for the connection
between the two structures in the
jaw. The gum is the present tissue of
the teeth, and the gum is simply the
skin layer Of the body folded inward
at the mouth to form the lining mem
brane of that cavity, while it is con
tinued onUard. with variations in its
organization, to form the lining Of the
digestive tubes as we'll Teeth are
therefore truly skin structures in re-
rpect Of their mode of origin, which,
after all. is the surest and indeed the
only test Of the nature of any living
tissue or part.
By all odds the very longest tooth in
the world is that of the narwhaI,
which grows into q twisted ivory pole
often exceeding six feet in length
4. Wilson in Illustrated London News.
Same Man.