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CHAPTER XVIII.

CAVITY PREPARATION FOR GOLD INLAYS.
Definition. An inlay is a body placed within a previously pre-
pared excavation. As applied to the filling of teeth it refers to the
process whereby the filling is inserted into the cavity of a tooth in
one piece and retained there, by the assistance of cement.
The Materials in most common use are porcelain, pure gold, al-
loj's of gold, as well as alloys of base metals.
The Indications for a Gold Inlay. First. In large contour
restorations, as there is a material saving of both time and energy
on the part of both patient and operator. Such cases, particular-
ly with posterior teeth are frequently crowned with the shell gold
crown with its almost universally irritating band, when the inlay
could be of greater service.
Second. When it is difficult to maintain dry conditions for a
long period of time about a cavity, as with large gingival cavities
in molars and bicuspids.
Third. When there are extensive occluding surfaces to be re-
stored. It is much easier to cast a correct contour than to build
up with the plugger point Avhich is largely guesswork when the
rubber dam is in position.
Fourth. When it is desired to put in a number of fillings in a,
given short time. In such cases the operator can nmke the wax
models, and engage the help of the laboratory in completing the
fillings while he is still busy with other fillings at the chair.
Fifth. When the necessary force to properly condense a cohe-
sive gold filling is not permissible, as Avitli loosened teeth, or in-
valid patients.
Gold Inlays Are Not Indicated in small cavities, or shalloAv cav-
ities, unless the outline is extensive.
The Cavity Preparation for a gold inlay does not materially dif-
fer from that which has already been advised in the preceding
chapters. It is possible to construct an inlay without change for
nearly every cavity which has been correctly prepared to receive
a cohesive gold filling. However if the order of precedure is slight-
ly rearranged the operation is simplified.
This Change in the Order would be to put retention form last, at-
tending to that part of the cavity preparation after the model
has been made and just before setting the inlay.
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