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272 OPERATIVE DENTISTRY
makes any attempt at interfering with the temporary arch already
established.
When this tooth is fully in place nature begins her work of re-
placement. First come the centrals, then the laterals, and if we
were to follow the order in which these same temporary teeth
were erupted Ave would next have the cuspid, but not so, Ave have
the first temporary molar lost and replaced by the first bicuspid,
and as this temporary molar is lost, the first bicuspid has a space
to occupy betAveen tAvo teeth, Avhich should be in position to guide
and assist it to proper place, leaving the second temporary molar
in position to hold the first permanent molar in its correct posi-
tion. Then nature replaces the second temporary molar with the
second bicuspid. Note that these tAvo temporary molars are AA'ider
than the permanent bicuspids taking their place, but the cuspid
of the permanent set is Avider than the temporary cuspid.
Loss of Temporary Cuspid. As soon as the temporary molars
have been replaced by the bicuspids, the temporary cuspids should
be lost and replaced by the permanent cuspids, AA^hich as stated
before, forms the keystone of the arch, and being a little Avider
Avedges the tAvo bicuspids quickly back into position against the
first permanent molar. Coming into position just in this order
and at this time it is easily seen hoAV the first permanent molar is
kept in its proper place. At this time the question may arise as to
hoAV the permanent centrals and laterals find sufficient room, be-
ing so much larger than their predecessors. This is compensated
for by the development of the maxillae at this age. Some authors
advance the idea that the difference in the space occupied by these
four teeth Avas compensated for by the permanent bicuspids being
smaller than the temporary molars. We cannot agree Avith this.
For Avhen the four incisor teeth are erupted in position in almost
every instance the temporary cuspid retains its former and original
place.
Having completed the changing of the temporary teeth nature
Avill add teeth to the posterior part of the jaAv Avithout any danger
of subsequent irregularities.
Evils Resulting From Disregarding- the Order in Which the
Temporary Teeth Are Replaced by the Permanent in Their Extrac-
tion. For instance, if, as Ave are frequently requested by our
patrons, we extract lateral incisors before the central incisors have
attained nearly their proper height in the process of eruption, either
one of the two evils may result.