Page 208 - My FlipBook

192 THE TREATMENT OF TEETH
to be taken in accurately filling up spaces, and if
small, deep, trench-like depressions are formed near
the margins, it is troublesome to fill them up and
secure clean margins.
The second method demands an accurate calcula-
tion of how far the heaped-up body will flow down
without producing plus contour, and it also demands
a long-continued fusing at just the right heat to
prevent over-fusing.
The third method does away with the production
of trenches or spaces that may be troublesome to
fill up. It enables the margins to be kept in view
all the time. If any of the body is allowed to flow
over, it will only be at certain parts, and a painting
back to an exact margin is easy. The whole
work proceeds gradually, layer by layer, and exact
margin and exact contour are assured. This method
demands a considerable number of fusings, but the
inlay grows gradually in a thoroughly well-defined
and accurate manner. Fusing to a biscuit bake
until the final fusing, is frequently recommended,
but this often causes the body to shrink consider-
ably when completely fused ; whereas if the inlay
is built up carefully, layer by layer, the first two
linings may be fully glazed, and every other fusing
brought to a rough or slightly wavy glaze until the
last layer is applied. When this last layer is fused