Page 410 - My FlipBook

260 PATHOLOGY OF THE HABD TISSUES OF THE TEETH.

year-old point. Somewhat rarely, much wider variations from
the average time is seen. In one case I saw the first permanent
molars through the gums and in occlusion at four years old.
Again, two little girls just five years old, cousins, had the first
molars in full occlusion. Delay to seven and a half and even
eight years has been known, but such delays are rare. The
roots of these teeth are rarely completed before the tenth or
twelfth year, giving four or five years after the eruption of the
crown for the development of the root, and, in many instances,
the length of the root is not complete until six years after
eruption. If we extract these teeth before the eleventh or twelfth
year we will generally find that the apical foramina have
not been closed down to a small opening. The important point
is the relation of this closure of the apical foramen to the
destruction and removal of the pulp and the filling of the roots.
The chart, Figure 187, represents the contemporaneous calcifi-
cation lines in figures placed upon each tooth, a figure for each
year during its development, representing the progress of its
calcification. By following any given figure from tooth to tooth,
the particular part of the root developed at the year represented
will be found. When information is desired regarding any
particular tooth, the figures placed upon it give the growth
for each year. The figures placed above the roots of the teeth
give the earliest date in the age of the child at which the apical
foramen of the roots have frequently been found sufficiently nar-
rowed to permit of root filling and the latest date at which
they have still been frequently found not sufficiently narrowed.
In this the occasional cases of abnormally early teeth and abnor-
mally late teeth are not included.
In considering the lengthening of the roots of the teeth,
we must give about another year after the root has attained
properly its length for the reduction of the size of the apical
foramen. The length of the root of the first molar, coming
through at six years, is sufficiently complete at from ten to
twelve years ; that is, from four to six years after its eruption.
The central incisors, erupting at six or seven, will have the
foramen sufficiently closed at about nine to twelve years ; three
to five years after eruption. "With all of the other teeth, we may
allow three to four years after eruption. The lateral comes
through at eight, will be completed from eleven to twelve; the
first bicuspid comes through at ten and will be completed at from
thirteen to fourteen; the second bicuspid at very nearly the
same time. The cuspid will be complete at about fifteen to