Page 31 - My FlipBook

"SELF-CLEANSING" SURFACES:

labially. Fig. 26 shows a similar section, the cavities having been
extended to what are described as "self-cleansing lines," represented
in the figure by the lines a, a, b, b. These lines indicate the surfaces
touched by the tongue as it is passed over the teeth. Observe that
the extension of the cavity-borders in the figure has been carried
beyond the points of actual contact between the tongue and tooth
(c), for it is plain that to make a border exactly upon this line
would be rather to invite than to it. A
decay prevent comparison of
these two figures shows to what a considerable extent extension of
FIG. 25. FIG. 26.

the cavity-borders must be carried to reach these imaginary ' ' self-
cleansing" surfaces, and I argue that when we consider the limitations
of this tongue- and lip-cleansing, as a tooth-saving influence, coin-
pared to the manifest disfigurement of the mouth by the greater
of of recurrence
display filling-material, the comparative infrequency
of these borders where gold has been
decay along properly placed,
and more than all the lessened retentive power of the cavity, or
greater approach toward the pulp, it follows that to extend an
approximal cavity in the six anterior teeth in any direction beyond

FIG. 27. FIG. 28. FIG. 29. FIG. 30.

the amount required for reaching a strong enamel-border is extremely
hazardous and unwise.
Extension of approximal cavities in bicuspids and molars is a dif-
Where such a occurs in a or molar
ferent subject. cavity bicuspid
distant from the masticating surface, it being either impossible or
it is better to extend the
unadvisable to obtain sufficient separation,
so as to access than to attempt to fill it with little
cavity gain ready
The in these cases that such extension must be
space. argument
rather than the buccal surface, is more often
toward the palatal