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34 MACROSCOPIC ANATOMY OF THE HUMAN TEETH.
from the triangular. They also become the seat ot" caries in imperfectly
formed teeth.
The neck of the first bicuspid is com])rcssed or s|)indlc-shitpcd
(/),
the enamel line rising- on the buccal and linoiial sides and di])j)ing
down on the mesial and distal. TJie enamel margin tapers oft' gradually
on to the root. A wide, deep depression usually occurs [a) on the mesial
side of the neck, leading to the groove on the root. On the distal face
this is not so well marked.
The root is much flattened mesio-distally, with a decaded groove ex-
tending up both sides. This grooving tends to cause bifurcation of the
root, which actually occurs in one-third of the cases, especially in persons
of strong build. This bifurcation is a persistent relic of lower forms
of the premolars, as in the apes.
The root canal is fiat at the neck, and nearly always bifurcated, even
when the root is not separated. This is readily seen by holding a bicus-
})itl having one root, up to the light, when the central portion will l)e ob-
served to be translucent. The usual bifurcation necessitates the search
for both canals in every case in treating this tooth.
The upper second bicuspid (w) approximates the first on the distal
side, and is similar to it in every way, except that it is usually smaller and
more rounded in all directions. The sharp features, conspicuous ridges,
etc. are not so strongly marked. The cusps are reduced, the ridges more
rounded, and the morsal face more flattened, and it is often wrinkled.
The triangular ridges are more likely to be united, thus making the crown
stronger. The crown is thinner mesio-distally. The neck is more
rounded or oval.
A most conspicuous difference is in the root, which is narrower labio-
lingually, is more rounded, and is rarely bifurcated. It is sometimes
cylindrical or cubical in form. It is disposed to be turned, and is often
crooke<^l. The ^yulp canal is single and readily entered.
13. The Lower Bicuspids.—These are placed next after the lower
canines on the distal side. In form they are not truly bicuspid, for the
first is unicuspid and the second is tricuspid in the pure typal forms
but they are arbitrarily termed bicuspids on account of their position as
compared with the upper bicuspids, which are typically bicuspid.
The architectural form of these teeth is that of the single cone, the
crown being augmented in various directions by the addition of cin-
gules to the primitive cusp.
The lower first bicuspid is a well-formed transitional tooth, for it
grades from canine to bicuspid and is typically composite. It more
closely resembles a canine than a bicuspid in its usual form, because
the inner cusp is almost suppressed and is rarely as large as the outer
one (Fig. 19, a). In fact, it looks like a canine with a cingule raised
34 MACROSCOPIC ANATOMY OF THE HUMAN TEETH.
from the triangular. They also become the seat ot" caries in imperfectly
formed teeth.
The neck of the first bicuspid is com])rcssed or s|)indlc-shitpcd
(/),
the enamel line rising- on the buccal and linoiial sides and di])j)ing
down on the mesial and distal. TJie enamel margin tapers oft' gradually
on to the root. A wide, deep depression usually occurs [a) on the mesial
side of the neck, leading to the groove on the root. On the distal face
this is not so well marked.
The root is much flattened mesio-distally, with a decaded groove ex-
tending up both sides. This grooving tends to cause bifurcation of the
root, which actually occurs in one-third of the cases, especially in persons
of strong build. This bifurcation is a persistent relic of lower forms
of the premolars, as in the apes.
The root canal is fiat at the neck, and nearly always bifurcated, even
when the root is not separated. This is readily seen by holding a bicus-
})itl having one root, up to the light, when the central portion will l)e ob-
served to be translucent. The usual bifurcation necessitates the search
for both canals in every case in treating this tooth.
The upper second bicuspid (w) approximates the first on the distal
side, and is similar to it in every way, except that it is usually smaller and
more rounded in all directions. The sharp features, conspicuous ridges,
etc. are not so strongly marked. The cusps are reduced, the ridges more
rounded, and the morsal face more flattened, and it is often wrinkled.
The triangular ridges are more likely to be united, thus making the crown
stronger. The crown is thinner mesio-distally. The neck is more
rounded or oval.
A most conspicuous difference is in the root, which is narrower labio-
lingually, is more rounded, and is rarely bifurcated. It is sometimes
cylindrical or cubical in form. It is disposed to be turned, and is often
crooke<^l. The ^yulp canal is single and readily entered.
13. The Lower Bicuspids.—These are placed next after the lower
canines on the distal side. In form they are not truly bicuspid, for the
first is unicuspid and the second is tricuspid in the pure typal forms
but they are arbitrarily termed bicuspids on account of their position as
compared with the upper bicuspids, which are typically bicuspid.
The architectural form of these teeth is that of the single cone, the
crown being augmented in various directions by the addition of cin-
gules to the primitive cusp.
The lower first bicuspid is a well-formed transitional tooth, for it
grades from canine to bicuspid and is typically composite. It more
closely resembles a canine than a bicuspid in its usual form, because
the inner cusp is almost suppressed and is rarely as large as the outer
one (Fig. 19, a). In fact, it looks like a canine with a cingule raised
