Page 148 - My FlipBook

144 OPERATIVE DENTISTRY

but all compressing force should be directed at a right angle to the
base wall.
Quite a body of excess should then be added to the occlusal por-
tion and a plugger point applied with mallet force which should be
augmented with hard hand pressure. The hand pressure and mallet
force combined will produce a more dense filling than by any other
method and at the same time crowd the yet movable particles of amal-
gam and alloy into closer adaptation to every portion of the cav-
ity walls.
Trimming Amalgam Fillings. After packing the amalgam it
should be allowed to set undisturbed for one or two minutes, when
the excess may be cut away with suitable knives. Gum lancet No.
2 and the discoid and cleoid from the ''University set" are service-
able, as are also the large spoon excavators.
Removal of Matrix. The matrix should then be removed in prox-
imal cavities by drawing to the buccal while pressing the ball of the
finger gently on the occlusal surface. A loosely rolled, rather large,
ball of cotton should be laid on the amalgam filling under the finger
tip, in order to prevent the matrix from traveling occlusally in the
process of removal.
The rubber dam should then be removed and the patient instructed
to slowly close the teeth, stopping the instant he feels the presence
of the filling between the teeth, which will occur if excess contour
has been l)uilt. With the teeth still held in this same position, the
patient is requested to give the jaws a gentle side movement. This
will result in burnishing the spots of contact, after which the excess
should be whittled away with knife-edged instruments.
Amalgam Should Be Cut From the Margins to the filling, which
is just the reverse from the travel of the instrument in cutting gold
fillings. If the cutting instrument moves from the filling to the cavo-
surfaee angle with amalgam that is only partially set, it is liable
to sink too deeply into the substance of the filling and expose the
margin as it crosses over.
Passing Contact Point. In proximal fillings of amalgam nothing
of any description should ever be allowed to pass the contact point
until the amalgam has completed the process of setting, as one such
attempt forever destroys proper contact and a filling so treated be-
comes at once a makeshift. All overhanging amalgam should be cut
away, around the entire cavity outline, but the region of contact
point should be entirely neglected at this time, and left for final
shaping during the process of polishing. Finally the filling should
be gently wiped with spunk or cotton.