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33 Natural History of the Teeth.
tioa is going on, the fang has the appearance of being broken
off, or rather eaten away by insects.
The period at which the shedding of the teeth, or the second
dentition commences, is quite various; in some the process
begins as early as the fifth or sixth year, and in others, not
until the eighth : between the sixth and seventh years, may
be taken as the standard time. The first four permanent mo-
lares usually make their appearance before the temporary
teeth begin to fall, and may be considered as an indica'.ion of
the approaching change.
Soon after the permanent molares have made their appear-
ance, the two central temporary incisores of the lower jaw be-
gin to loosen and fall out ; the permanent central incisores
soon after appear : in two or three months the central tempo-
rary incisores of the upper jaw become loose and drop out
and are succeeded by the two permanent ones : in two or three
months more, the same changes take place with the lateral
incisores of both jaws, those of the lower jaws falling first: in
about six or twelve months more the temporary molares fall,
and are succeeded in due time by the permanent bicuspides :
the temporary molares generally fall before the cuspidati or
eye teeth, the long fangs of which require a longer time to be
absorbed : the permanent incisores and cuspidati take the places
of the same temporary teeth ; the permanent bicuspides, the
places of the temporary molares ; and the permanent molares,
occupy the space made by the increase of the maxillary bones,
after the completion of the first dentition.
The following is Mr. Bell's table of the medium periods, at
which the different permanent teeth are cut, but so irregular
are they in this respect, that little dependance can be placed
in such a statement. The table refers to the teeth of the lower
jaw, which commonly precede those of the upper by two or
three months.
Anterior molares, *6i years.
Central iucisores, ----- 7
33 Natural History of the Teeth.
tioa is going on, the fang has the appearance of being broken
off, or rather eaten away by insects.
The period at which the shedding of the teeth, or the second
dentition commences, is quite various; in some the process
begins as early as the fifth or sixth year, and in others, not
until the eighth : between the sixth and seventh years, may
be taken as the standard time. The first four permanent mo-
lares usually make their appearance before the temporary
teeth begin to fall, and may be considered as an indica'.ion of
the approaching change.
Soon after the permanent molares have made their appear-
ance, the two central temporary incisores of the lower jaw be-
gin to loosen and fall out ; the permanent central incisores
soon after appear : in two or three months the central tempo-
rary incisores of the upper jaw become loose and drop out
and are succeeded by the two permanent ones : in two or three
months more, the same changes take place with the lateral
incisores of both jaws, those of the lower jaws falling first: in
about six or twelve months more the temporary molares fall,
and are succeeded in due time by the permanent bicuspides :
the temporary molares generally fall before the cuspidati or
eye teeth, the long fangs of which require a longer time to be
absorbed : the permanent incisores and cuspidati take the places
of the same temporary teeth ; the permanent bicuspides, the
places of the temporary molares ; and the permanent molares,
occupy the space made by the increase of the maxillary bones,
after the completion of the first dentition.
The following is Mr. Bell's table of the medium periods, at
which the different permanent teeth are cut, but so irregular
are they in this respect, that little dependance can be placed
in such a statement. The table refers to the teeth of the lower
jaw, which commonly precede those of the upper by two or
three months.
Anterior molares, *6i years.
Central iucisores, ----- 7
