hat may have lodged between them.
Toothpicks may be useful in removing any particles inaccessible to the
brush. They may be made of bone, ivory, or the common goose-quill.
Metallic toothpicks should not be used, as they injure the enamel.

224. _The mouth should be cleansed with pure tepid water at night, as
well as in the morning_; after which the teeth should be brushed
upward and downward, both on the posterior and anterior surfaces. It
may be beneficial to use refined soap, once or twice every week, to
remove any corroding substance that may exist around the teeth; care
being taken to thoroughly rinse the mouth after its use.

225. _Food or drink should not be taken into the mouth when very hot
or very cold._ Sudden changes of temperature will crack the enamel,
and finally produce decayed teeth.

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222. What is another use of the teeth? 223-232. _Give the hygiene of
the teeth._ 223. How can the teeth be preserved? By what means? 224.
How often should they be cleansed? 225. What is said of very hot or
cold drinks?

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_Observation._ On this account, smoking is pernicious, because the
teeth are subjected to an alternate inhalation of both cold and warm
air.

226. _The temporary teeth should be removed as soon as they become
loose._ If a permanent tooth makes it appearance before the first is
removed, or has become loose, the milk tooth, although not loose,
should be removed without delay. This is necessary that the second set
of teeth may present a regular and beautiful appearance.

227. _In general, when the permanent teeth are irregular, one or more
should be removed._ If the teeth are crowded and irregular, in
consequence of the jaw being narrow and short, or when they press so
hard upon each other as to injure the enamel, remove one or more to
prevent their looking unsightly, and in a few months the remaining
teeth, with a little care, will fill the spaces.

_Observation._ When it is necessary to remove a tooth, apply to some
skilful operator. It requires as much skill and knowledge to extract
teeth _well_, as it does to amputate a limb; yet some persons, who
possess strong arms, will obtain a pair of forceps, or a tooth-key,
and hang out the sign of "surgeon-dentist," although ignorant of the
principles that should guide them.

228. _It is not always necessary to have teeth extracted when they
ache._ The nerve, or the investing membrane of the root,