He says nothing in regard to the filling of decayed teeth; he, however, counsels the cleansing of the carious cavities with aqua fortis, or even, in some cases, the widening of them, in order to render them shallower and therefore less liable to retain alimentary residues. Pietro of Argelata cured dental fistulas by means of caustics and arsenic. He counselled simple palliative means of cure for hard epulides of a cancerous nature. In regard to soft, benignant epulides, he was little favorable to excision, as this might cause hemorrhage; he preferred ligating the tumor; or he repeatedly cauterized it with boiling oil or other caustics, until he caused it to fall.[260] BARTOLOMEO MONTAGNANA, who taught surgery in the University of Padua and died in 1460, recommended, as an excellent anti-odontalgic remedy, a mixture of camphor and opium. In his days, faith in the pretended eradicating virtues of certain substances was being gradually lost; but, on the other hand, a tendency now arose to neglect, in regard to the teeth, the conservative principle, to which the ancients had held so jealously; and little by little the extraction of a tooth began to be considered an operation of small or no importance, that could be performed with the greatest indifference. Montagnana himself considers the extraction of a tooth as the best means of curing odontalgia, whilst the ancients did not have recourse to it, saving as a last resource. Notwithstanding this, if the caries was not deep, he preferred to extraction the use of caustics and a red-hot iron.[261] GIOVANNI PLATEARIO, a professor at Pisa in the latter half of the fifteenth century, cauterized carious teeth with a small piece of kindled ash wood, or with a red-hot iron, and held that cauterization was more effectual when, before performing it, the carious hollow had been filled up with theriac.[262]