Page 31 - My FlipBook

DYSTROPHIES OF THE TEETH. O
Likewise one should be familiar with the lines of accretion
of the enamel — the lines of Eetzius — as shown in Figure 10.
Each of these lines represents a period of growth of the enamel
— a layer, all of which was constructed during a given time.
It is without the province of this writing to go into detail in
these matters, and the student is referred to the several authori-
tative works on dental histology.
ATROPHY OF THE TEETH.
Hypoplasia of the Teeth.
A contemporaneous accretional deformity — a dystrophy in
which all portions of the teeth in process of formation at a par-
ticular time are imperfectly formed along the lines of normal
accretion or growth.
As in the previous editions of this work, the term atrophy is
applied to this condition, also the term hypoplasia, which has
been used widely in the German writings. Because of the fact
that the application of both of these terms has been too general,
has included all kinds of deformities, and also because of the
fact that the term atrophy represents two distinct ideas in medi-
cal literature, I am of the opinion that both terms should be
dropped as applied to this condition. The term atrophy has
been applied to a failure of development of a local part because
of a failure of nutrition ; it has also been applied to the wast-
ing of a part because of a local failure of the nutritive process.
The term atrophy has been used to designate this condition
since it was first spoken of in the English language.
The contemporaneous accretional deformities of the teeth
represent an atrophy of the first mentioned type ; they have
never been fully formed. They come through the gums in the
condition of deformity in which they are afterward seen, and
do not, as some seem to suppose, waste away after having taken
their places in the arch. The deformity is a result of incomplete
formation.
In the human teeth there is no process of repair and the
deformity is permanent. Similar phenomena occur in the finger
nails and the hair. During an illness that interferes seriously
with nutrition, the portion of the finger nail then forming will
be dwarfed, which will appear later as a groove across the nail.
This, like the marking of the teeth, is not remedied by any repar-
ative process. But the nail is continuously growing and the
groove moves on over the length of the nail and disappears.
During a severe illness that interferes with nutrition, a sec-