Foreest is the first to speak of the violent inflammation of the gums and of the whole mouth, caused by the application of artificial teeth of ivory fixed in their place with gold wire. This cannot at all astonish us when we consider how imperfectly, in those days, dental prosthesis was carried out and how the immobility of the artificial pieces, caused them to be a source of permanent irritation to the neighboring parts, especially on account of the difficulty met with in giving proper care to cleanliness. He, therefore, entirely rejects the application of artificial teeth. He is likewise but little inclined to the use of the pelican, it being very easy to break the teeth with it, and, instead, he recommends the use, whenever it be possible, of another instrument which he calls _pes bovinus_. Foreest relates several cases of dental fistulæ which he had cured by the extraction of the faulty teeth. In one of these cases, observed in a lady, the fistula had opened between the nose and the cheek, so that a malady of the upper jaw was feared (and, in fact, as William Sprengel observes, it is not improbable that this was a case of affection of Highmore’s antrum); he obtained a complete cure in a short time by the extraction of a diseased tooth. According to Peter Foreest, the existence of dental worms is as certain as is that of intestinal, auricular, and other worms. Even on the pretended efficacy of remedies, capable of making the teeth fall out without pain, he does not throw the slightest doubt. Foreest attributes to his master, Benedictus of Faenza, the merit of having introduced into therapeutics the trephining of teeth for the cure of certain violent pains not accompanied by any external lesion of the tooth. We know, however, that the invention of this operation dates back to Archigenes. Benedictus trephined the tooth with a very fine drill (_stylo vel terebello subtilissimo_) and then filled it with theriac, using, likewise, as occasion required, other remedies. To demonstrate the propriety and the necessity of laying bare the neck of the tooth before extracting it, he relates a case in which fracture of the jaw was the result of having neglected this precaution. Among the sundry causes of the looseness of teeth, he mentions the softening of the dental nerve (_emollitio_), but this erroneous opinion had already been expressed by Galen. As a means of cleaning teeth and keeping them free from tartar, he advises, among other things, the use of pumice-stone powder. He disapproves, however, of the use of oil of vitriol—unless in very minute quantities of, at the very most, one or two drops.[317]