ater,
but this is not such a great detriment, for they can easily be repaired
or replaced, and owing to the concave form produced by wear the patient
is liable to know when a large amount has been worn away. That portion
against the wall of the cavity is the last removed by wear, so that
further caries is prevented so long as there is any reasonable amount of
tin left. If at this time the tooth has become sufficiently solidified,
proper anchorage can be cut in the tin or tooth, one or both, as
judgment dictates, and the filling completed with gold. A tin filling,
confined by four rather frail walls, may condense upon itself, but it is
so soft and adaptable that the force which condenses it continually
secures the readaptation at the margin; thus there will be no leakage or
caries for years. Owing to its softness and pliability, it may be driven
into or onto the tubuli to completely close them from outside moisture,
and with a hand burnisher the tin can be made to take such a hold on
dry, rough tubuli that a cutting instrument is necessary to remove all
traces of it.

Tin foil has been found in the market that under a magnifying glass
showed innumerable tiny black specks, which, upon being touched with an
instrument, crumbled away, leaving a hole through the foil. More than
likely, some of the failures can be attributed to the use of such foil.
Good tough foil, well condensed by hand or mallet force, stays against
the walls of a cavity and makes a tight filling, and ought to be called
as near perfect as any filling, because it preserves the tooth, and
gives a surface which will wear from five to twenty years, depending
upon the size and location of the cavity and tooth-structure. Buccal
cavities in the first permanent molars, and lingual cavities in the
superior incisors, filled for children from six to eight years of age,
are still in good condition after a period of twenty years. Perhaps the
limit is reached in the following cases, all in the mouths of
_dentists_: One filling forty years old; one forty-two; four on the
occlusal surface, fifty; in the latter case gold had been used in other
cavities and had failed several times. Lingual cavities in molars and
bicuspids can be perfectly preserved with tin. Tapes of No. 10 foil,
from one to three thicknesses, can be welded together and will cohere as
well or better than semi-cohesive gold foil, and it can be manipulated
more rapidly; therefore, if desirable, any degree of