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SILICATE IN THE MAKING OF A FILLING
151
would therefore follow that the primary contact should be greater
and broader. In other words, if we are to use the marble contact
it should be the contacting of larger marbles than in the more dur-
able metal fillings. To put it in other words, the convexity of the
filling's surface should be the segment of a larger circle than the
metal filling. Proper separation is essential.
Outline Form. In the consideration of outline form, the same
rules should apply as when using any other filling. We should ex-
•tend cavity margins until all surface decay has been included. With
other filling materials, we sometimes falter in this because of the un-
sightly results, but with silicate, when the color has been properly
chosen, there should be no hesitancy, as large fillings are generally
Fig. 83. Fig. 84.
Fig. 83. A Class Five cavity properly prepared for a silicate filling. The decay is shown
in Fig. 82.
Fig. 84.—A Class Three cavity, lingual approach, properly prepared for a silicate filling.
The decay is shown in Fig. 82.
as little observed as small ones, especially on flat labial and buccal
surfaces. When fissures and sulcate grooves are encountered, they
should always be included in the outline, as a leaky filling will re-
sult at the triangular space formed where the sulcate grooves meet
the filling.
Resistance Form. In dealing with resistance to the crushing
strain, we have a greater problem to solve than in the use of almost
any other material. The edge of the filling is more easily broken,
and after some months or years of wear there is great danger of ex-
posure of the cavo-surface angle. It is therefore necessary to lay
SILICATE IN THE MAKING OF A FILLING
151
would therefore follow that the primary contact should be greater
and broader. In other words, if we are to use the marble contact
it should be the contacting of larger marbles than in the more dur-
able metal fillings. To put it in other words, the convexity of the
filling's surface should be the segment of a larger circle than the
metal filling. Proper separation is essential.
Outline Form. In the consideration of outline form, the same
rules should apply as when using any other filling. We should ex-
•tend cavity margins until all surface decay has been included. With
other filling materials, we sometimes falter in this because of the un-
sightly results, but with silicate, when the color has been properly
chosen, there should be no hesitancy, as large fillings are generally
Fig. 83. Fig. 84.
Fig. 83. A Class Five cavity properly prepared for a silicate filling. The decay is shown
in Fig. 82.
Fig. 84.—A Class Three cavity, lingual approach, properly prepared for a silicate filling.
The decay is shown in Fig. 82.
as little observed as small ones, especially on flat labial and buccal
surfaces. When fissures and sulcate grooves are encountered, they
should always be included in the outline, as a leaky filling will re-
sult at the triangular space formed where the sulcate grooves meet
the filling.
Resistance Form. In dealing with resistance to the crushing
strain, we have a greater problem to solve than in the use of almost
any other material. The edge of the filling is more easily broken,
and after some months or years of wear there is great danger of ex-
posure of the cavo-surface angle. It is therefore necessary to lay
