Page 303 - My FlipBook

REPAIRIXG FILLINGS. 301

described above. Disks of sandpaper and emery cloth and finer ones
charged with cuttlefish powder (Fig. 271) are exceedingly useful in
shaping and polisliing the filling. Fig. 272 shows two forms of disk
mandrels wiiich may be satisfactorily used in carrying disks.
Fig. 272.
%1M1\1B» ( j fc : 1^=1 __L^-_-3:^l^^
i
|
Huuv disk mandrul.

Morsrau-Mastield disk mandrel.
Many approximal fillings in the bicuspids and molars extend to the
occlusal surface. When this is the case the operator should pay special
heed to the occlusion of the opposing teeth. If left too full tlie con-
stant touching of an opposing cusp may batter the filling, or, if not
securely anchored, dislodge it. Overlap])ing gold is the rock of offence,
and is the cause of many failures. A filling is not well finished until
a delicate instrument can be passed from enamel surface to filling with-
out catching. When this can be done, and dental floss is not fraved at
the cervical margin, the inference is justified that no gold has been left
overlapping.
Repairing Fillings.
Fillings somewhat defective are often susceptible of repair. The
defect may sometimes be apparent in the finishing ; at other times it
is the result of subsequent caries, and at still other times the result of a
fracture of the tooth enamel along the border of the filling'.
The nature of the defect and the condition of the remaining filling
must be taken into consideration before an effort to repair is undertaken.
When the defect is due to insufficient gold at any point in the filling
more gold may be added. It is well to first cut out a portion of the
filling, making a distinct cavity of retentive shape. Cohesive gold is
usually best suited to the purpose
; crystal gold often serves well in
the repair of such defects.
If the filling has been thoroughly condensed and the mass is solid
there is little difficulty in adding more gold to it, provided the surface
be clean. If it has been wetted with saliva, the surface of the gold
must be made not only dry but clean. It is well to wipe it with a
pellet of cotton or paper saturated with alcohol or ether, after which
the filling should be scraped with a suitable instrument. If the fill-
ing be of considerable size and well anchored, shallow retaining pits