7. _The application of artificial teeth._ These teeth, says Dionis, are generally made of ivory, but may also be made of ox bone, which is less liable to turn yellow than ivory. He does not mention the use of hippopotamus tusks, but we learn from him that one Guillemeau made artificial teeth with a composition of his own invention, which was obtained by fusing together white wax and a small quantity of gum elemi, and then adding ground mastic, powder of white coral and of pearls. This fact is, as everyone can see, most important, for it constitutes the first step toward the manufacture and use of mineral teeth. Dionis tells us that the teeth made of Guillemeau’s composition never became yellow, and that it was also very good for stopping decayed teeth.[392] It would seem, therefore, that it could be used as cement is now used. The Guillemeau of whom Dionis speaks is probably Jacques Guillemeau, the author of a book now no longer to be found, which was translated from the French, first into Dutch, and afterward into German. Crowley, in his _Dental Bibliography_, only quotes the German edition, published at Dresden in 1710, the title of which runs thus: _Der aufrichtige Augen und Zahnarzt_.[393] JEAN VERDUC, also a Frenchman, relates a case of the surgeon Carmeline,[394] analogous to that of Denis Pomaret, in which a sound tooth which had been extracted by mistake was immediately replanted and took root again, becoming quite firm. However, Verduc does not speak of replantation as a special method of cure, but merely refers to the above case incidentally in speaking of the extraction of teeth. He considers this operation a most dangerous one, and advises not having recourse to it except in cases of utmost necessity. Notwithstanding this, Verduc gives us to understand that teeth were drawn with sufficient ability by most of the operators of the time, and precisely because of this he omits describing the manner of performing the operation. According to Verduc, the drawing of teeth is often of little or no advantage against toothache.[395] In proof of this assertion he relates the case of a hypochondriac, who little by little had as many as eighteen teeth extracted, without, however, getting the better or the wiser; but as this case does not prove anything at all, one is disposed to think that Verduc, in relating it, had the intention of being humorous. MONSIEUR DE LAVAUGUYON. To another French surgeon, Monsieur de Lavauguyon, also a contemporary of Dionis, belongs the merit of having declared useless, in the greater number of cases, the practice, at that time general, of separating the gums from the tooth before proceeding to the extraction of the latter. He says that this is only necessary when a tooth, either because broken or because its crown emerges too little above the gum, offers an insufficient hold for the pelican.[396]