Page 352 - My FlipBook
P. 352
;
350 COMBINATION FILLINGS.
round and round the tooth and matrix until it nearly covers both, or at
least sufficiently to insure its remainino; in ])laec during the operation.
A knot may be tied each time the silk is wound around the tooth, or
not, as appears to be necessary. Sometimes, Avhen the sides of the
tooth are sloping, the ligature has a tendency to slip oif. This can
usually be overcome by turning ba(!k, with tweezers, the two upper
corners, as shown in Fig. 331. To saturate the ligature wdth sandarac
or other sticky varnish will sometimes be sufficient to prevent the same
tendency.
Fig. 327 illustrates a simple and delicate, but very powerful, little
Pj^ gf,y slip matrix which is of great efficiency
in the treatment of occluso-approximal
cavities. They were conceived originally
for the plastics, in which case they are
left in place over night (the plastics thus
setting under pressure), slipping out easily the next day away from the
then hardened and perfectly contoured surface of the filling.
" They are most easily made, even for each case (though in practice
this is not necessary, as they may be employed over and over again),
as follows: Suitable-shaped pieces, of a size to a little more than over-
lap the cavity margins, are cut from thin . . . steel, ... all corners
and burred edges smoothly finished ; a tiny hole is punched close to
the middle of both the buccal and lingual edges, and it is then laid
upon a piece of lead and swaged (not merely bent, be it remarked) into
perfect concavity, greater or less as the individual case shall require,
by tapping with a hammer a convex rod of hardened steel laid upon it
my own instrument being a round-headed picture nail, case-hardened,
polished, and with twisted wire attached at right angles to a handle.
Any amount or shape of concavity required for each case can thus be
produced in a moment, either newly from blanks kept ready or changes
made in those used for other cases to fit the one in hand, about a
dozen of different sizes and degrees of convexity being sufficient to
select from, with little or no changes for all ordinary cases. The
tapping having re-stiffened the steel somewhat, taken in connection
with the impingement of the convex face against the approximal
surface of the adjoining tooth, gives firmness and strength to these
delicate little strips and a perfect hugging fit to the surfaces of the
tooth being filled, especially at its cervical margin, that is most
^
satisfactory."
When the cavity involves a large portion of the crown, or the mesial
and distal surfaces, the matrix should be long enough to almost encircle
^ Dental Cosmos, June 1898, vol. xl. No. 6, p. 452.
350 COMBINATION FILLINGS.
round and round the tooth and matrix until it nearly covers both, or at
least sufficiently to insure its remainino; in ])laec during the operation.
A knot may be tied each time the silk is wound around the tooth, or
not, as appears to be necessary. Sometimes, Avhen the sides of the
tooth are sloping, the ligature has a tendency to slip oif. This can
usually be overcome by turning ba(!k, with tweezers, the two upper
corners, as shown in Fig. 331. To saturate the ligature wdth sandarac
or other sticky varnish will sometimes be sufficient to prevent the same
tendency.
Fig. 327 illustrates a simple and delicate, but very powerful, little
Pj^ gf,y slip matrix which is of great efficiency
in the treatment of occluso-approximal
cavities. They were conceived originally
for the plastics, in which case they are
left in place over night (the plastics thus
setting under pressure), slipping out easily the next day away from the
then hardened and perfectly contoured surface of the filling.
" They are most easily made, even for each case (though in practice
this is not necessary, as they may be employed over and over again),
as follows: Suitable-shaped pieces, of a size to a little more than over-
lap the cavity margins, are cut from thin . . . steel, ... all corners
and burred edges smoothly finished ; a tiny hole is punched close to
the middle of both the buccal and lingual edges, and it is then laid
upon a piece of lead and swaged (not merely bent, be it remarked) into
perfect concavity, greater or less as the individual case shall require,
by tapping with a hammer a convex rod of hardened steel laid upon it
my own instrument being a round-headed picture nail, case-hardened,
polished, and with twisted wire attached at right angles to a handle.
Any amount or shape of concavity required for each case can thus be
produced in a moment, either newly from blanks kept ready or changes
made in those used for other cases to fit the one in hand, about a
dozen of different sizes and degrees of convexity being sufficient to
select from, with little or no changes for all ordinary cases. The
tapping having re-stiffened the steel somewhat, taken in connection
with the impingement of the convex face against the approximal
surface of the adjoining tooth, gives firmness and strength to these
delicate little strips and a perfect hugging fit to the surfaces of the
tooth being filled, especially at its cervical margin, that is most
^
satisfactory."
When the cavity involves a large portion of the crown, or the mesial
and distal surfaces, the matrix should be long enough to almost encircle
^ Dental Cosmos, June 1898, vol. xl. No. 6, p. 452.
