When teeth become loose he advises that they be fastened to the healthy ones with a gold chain. Guerini, in his "History of Dentistry" (Philadelphia, 1907), suggests that he evidently means a gold wire. If the teeth fall out Chauliac recommends that they be replaced by the teeth of another person, or with artificial teeth made from ox-bone, which may be fixed in place by a fine metal ligature. He says that such teeth may be serviceable for a long while. This is a rather curt way of treating so large a subject as dental prosthesis, but it contains a lot of suggestive material. He was quoting mainly the Arabian authors, and especially Abulcassis and Ali Abbas and Rhazes--and these of course, as we have said, mentioned many methods of artificially replacing teeth, as also of transplantation and of treatment of the deformities of the dental arches. Guerini called particular attention to the fact that Chauliac recognized the dentists as specialists. He observes that operations on the teeth are in a class by themselves, and belong to the _dentatores_ to whom they had been entrusted. He remarks, however, that the operations on the mouth should be performed under the direction of a surgeon. It is in order to give surgeons the general principles by means of which they may be able to judge of the advisability or necessity for dental operations, that his brief presentation of the subject is made. If their advice is to be of value, physicians should know the various methods of treatment suitable for dental diseases, including "mouth washes, gargles, masticatories and ointments, rubbings, fumigations, cauterizations, fillings, filings," as well as the various dental operations. He says that the _dentator_ must be provided with appropriate instruments, among which he named scrapers, rasps, straight and curved, spatumina, elevators, simple and with two branches, toothed tenacula, and many different forms of probes and cannulas. He should have also small scalpels, tooth trephines, and files. After Guy de Chauliac, the most important contributor to dentistry is Giovanni of Arcoli--or simply Arcolano, but sometimes better known by his Latin name Johannes Arculanus--who was Professor of Medicine and Surgery at Bologna just before and after the middle of the fifteenth century. He is sometimes treated in history as belonging rather to the Renaissance, but he owed his training to the Middle Ages and was teaching before they closed, so he has a place in Medieval Medicine. Guerini, in his "History of Dentistry," says that Arculanus treats the subject of dentistry rather fully and with great accuracy. The Italian historian makes a summary of Arculanus's rules for dental hygiene which shows how thoroughly he appreciated the care of the teeth. The medieval surgeon arranged his rules in ten distinct canons, creating in this way a kind of decalogue of dental hygiene.