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The case is quite the reverse with the bony part, for when
a tooth is first seen through the gum scarcely more than two
thirds of the fangs are formed, but the ossification continues
for a considerable time afterwards. The enamel upon some
teeth has a very defective formation ; instead of being a
hard white substance having a smooth polished surface, it is
frequently met with of a yellow colour, and having a great
number of indentations upon its surfaces. This occasions the
teeth to resemble the exterior of a sponge, and gives them
what has been termed a honey-combed appearance.
Sometimes this appearance* of the enamel is only met
with on the front teeth, near the cutting edge, at others it
extends nearly over half of the tooth, the remaining parts
being perfect. When the roughness is near the edge, it often
wears out in a few years, or at the age of maturity it may be
filed out. In some cases one, two, or three indented lines,
pass across the front of the teeth.
This defective formation of the enamel is usually confined
to the ineisores, cuspidati, and first permanent molares
; it is
rarely met with on the bicuspides, or second and third
molares.
The arteries which supply the teeth with blood are called
the dental ; they are branches of the internal maxillary arte-
ry which arises from the external carotid, at that part where
it is covered by the parotid gland, and lies behind the mid-
dle of the upright plate of the lower jaw where it divides
into the condyloid and eoronoid processes. It passes first
between the jaw and the external pterygoid muscle, and

* This may, and frequently does arise, from some cause (hat mechan-
ically disturbs the membranes before ossification is completed ; for the
enamel is exactly of the shape and figure of the membranes from which,
k is formed.
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