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HISTORY OF DENTAL SURGERY 357

the top of the pivot is capped, and the whole soldered together, thus fixing the
tootli.
"Anotlier method was to construct a mineral tooth in form and in the
thickness of the projection backward, upon the middle of the upper surface,
to make a vertical hole: in this liole are fixed the cramps destined to be sol-
dered to the shaft or pivot which is to fill this hole, or to a little platina tube
to receive tlie shaft. Most of the English teeth are tube teeth.
"The paste and enamel of whicJi I make mineral teeth are obtained from
the porcelain manufactories of Paris, and I have them burnt in tlie furnaces
of tliese establisliments.
"Impressions are taken with a mass of softened wax molded to the mouth
witli the fingers, or else the wax is put in a box, a kind of semi-elliptical gutter
of tin or silver, upon the anterior part of which is a shaft which forms a han-
dle.
"The impression is filled with plaster, or melted sulphur when about to
congeal, and from tliis model is made metal dies on which the plate is swaged.
"Tlie implantation of a pivot tooth is one of the most common operations
of dental prosthesis. We implant one or more pivots in a tooth, either to fix
it on a root, or to mount it upon some base. We use gold and platina pins,
and metal screw pivots, the latter of which holds the best.
"I mount bone teeth and human teeth upon metal plates.
"The great shoal of the partisans of mineral bases of small dimensions, as
of complete bases, is in the shrinkage of the paste (body) which prevents ac-
curacy and which is comparative, compared with that obtainable from me-
tallic or hippopotamus bases. We sought in vain to take the precaution of
making the paste one-seventh or eighth, or ninth larger than it is to be; or if
definitely fixing its dimensions after it has become dry, as Audibran advises,
this difficulty might be diminished but not obviated.
"These bases can only Ite employed for full sets. De Chemant himself
was so struck with the fragility of partial porcelain plates that he renounced
them, and preferred to make as many isolated pieces as he had vacancies to
fill, except when he held tliem united by means of a piece traversing the in-
ternal part of the dental arch.
"Delabarre mounted mineral teeth witli pivots soldered upon a plate ; then
he furnished the spaces which existed between this and the teeth with porcelain
earth moistened, and submitted tiie piece to the action of the fire.
"Audibran pronounces the most formal condemnation of this work, and
'
Lefoulon says that we are fortunate if we ol)tain one perfect piece out of six
trials.