Page 133 - My FlipBook

APPROXIMAL C. 1 1 'ITIES IX BICUSPIDS. 1 19

nearly to the gum line, the same difficulty is manifestly increased. I
have seen teeth of this nature which resisted all efforts to
persistently
obtain much space, and which, containing extremely large but shallow
cavities, became excessively tedious in the filling, because only very
small pieces could be properly carried to place. Yet we are told that
a steel is sufficient for all and
separator purposes, again that a matrix
should be placed around all approximal cavities in bicuspids and in
molars ! I must give a few illustrations to show the main differences
in preparation of cavities, from what has been already said.
In Fig. 128 we see a bicuspid in which I have indicated two small
cavities. It is evident that either of these would be itself
simplicity
in the absence of the adjacent tooth, in which case abundance of space
would give ready access. In an ordinary tooth where a fair separation
is procurable, either would still be manageable. With inadequate
space, and in a wide tooth, either of these will harass both patient and
operator if the attempt be made to prepare and fill without extension of
the cavity. A pellet of gold crowded between the teeth will be so
compressed that by the time it is forced into the cavity itself it is unfit
for use, quickly balling up so that it must be discarded. Again and
the same to lose
again mishap may occur, until it becomes easy patience
of alone should be so
at the difficulty what from its shape simple.
filling
But with inadequate space no cavity is simple, and I might almost say
the smaller it is the more annoying it will be. Therefore, in such cases
I should recommend extension of the cavity to make it accessible.
The direction of this extension depends upon the position. It should
be toward the labial surface, or the crown, as it happens to be nearer
the one or the other. For this reason the illustration shows two cavi-
ties, the position of one of which makes extension
toward the labial surface preferable, as shown by
the dotted lines, whilst in the other I would cut
to the crown. will be
through The first practice
resorted to less frequently in the mesial than in the'
distal surface, because of the probable showing of
To cut to the crown will be
the filling. through
chosen oftener on either approximal surface. I
must pause here a moment to defend this propo-
sition. It has been argued by a skillful operator, and careful thinker
and writer, that the crown of a bicuspid or molar should under no cir-
cumstances be disturbed in this way. An allusion is made to the simi-
here to the of an arch. That is, the of the tooth
larity strength portion
which I advise this writer claims is as the arch to the cavity,
removing,
and its greatest protection. A better argument that he uses is, that it
assists in holding together the labial and palatal plates. All of this is
beautiful theory ; but to my mind it is illusory, if not false. Given a