Page 188 - My FlipBook

186 PRELIMINAnr PREPARATION OF THE TEETH.

iiciciit ()])('nino; is eifbctod, the sjiacc llicii Ucing secured hy anotlier wedo;e
of luinl close-jrniiiu'd wood forced Ix'tween the teetli at tlie cervix. This
process in some instances is repeated l)v forciii«; fartlier the first wedge
and again increasing the security by (h-i\'iiig the cervical wedge. Tliin
plan is not apjilicahle when the inters])a(!e at the neck is quite angular,
since the fixing w'cdgc cannot be made secure, as it then is disposed
to advance against the gum. In this case one of the subsequent
methods should be pursued.
If the fixation of the teeth be not firm they yield by a slight enlarge-
ment of the arch and by closing the neighboring slight sjxices.
Immediate separations may be effected by mecJianical separators,
notablv the William A. A\'oodward (see Fig. 150), for the front teeth and

Fig. 150. Fig. 151.

Woodward's separator. Perry's separator in conjoint use with matrix.
the Perry (see Fig, 151) for the bicuspids and molars. It should be
stated that each of these is preferably to be used when some previous
space has been made by other means, following which a considerable
increase of space may be secured by these appliances.
Separation by the Swelling- of Fibrous Materials.—These act by
the capillary force of water upon the fil)rous structure of the material,
whether pledgets of cotton or tape. This means is also more applica-
ble when the fixation of the teeth is not firm, and has the advantage of
being painless and more readily tolerated by children and by persons
Avho are impatient of pain or of any form of dental distress.
Pledgets of cotton are more applicable where a partial preliminary
opening of a carious cavity has been made, and are more appropriate for
the posterior teeth. Here, when there is no danger of pulp exposure,
the pledgets may be packed with considerable firmness. In some
instances it is advantageous to saturate the pledget with thin sandarac
varnish, which attaches the fibers, but the time required is much in-
creased, as the cotton yields to capillary attraction only as it loses the
resin.
Tape is more useful for the incisors it should l)e of linen and may
;
or may not be waxed. Its entrance is facilitated by an immediate pre-
liminary application of a wooden wedge.