Chauliac is particularly emphatic in his insistence on not permitting alimentary materials to remain in the cavities, and suggests that if cavities between the teeth tend to retain food material they should even be filled in such a way as to prevent these accumulations. His directions for cleansing the teeth were rather detailed. His favourite treatment for wounds was wine, and he knew that he succeeded by means of it in securing union by first intention. It is not surprising, then, to find that he recommends rinsing of the mouth with wine as a precaution against dental decay. A vinous decoction of wild mint and of pepper he considered particularly beneficial, though he thought that dentifrices, either powder or liquid, should also be used. He seems to recommend the powder dentifrices as more efficacious. His favourite prescription for a tooth-powder, while more elaborate, resembles to such an extent at least, some, if not indeed most, of those that are used at the present time, that it seems worth while giving his directions for it. He took equal parts of cuttle-bones, small white sea-shells, pumice-stone, burnt stag's horn, nitre, alum, rock salt, burnt roots of iris, aristolochia, and reeds. All of these substances should be carefully reduced to powder and then mixed.

His favourite liquid dentifrice contained the following ingredients : Half a pound each of sal ammoniac and rock salt, and a quarter of a pound of saccharin alum. All these were to be reduced to powder and placed in a glass alembic and dissolved. The teeth should be rubbed with it, using a little scarlet cloth for the purpose. Just why this particular colour of cleansing cloth was recommended is not quite clear.

He recognized, however, that cleansing of the teeth properly often became impossible by any scrubbing method, no matter what the dentifrice used, because of the presence of what he called hardened limosity or limyness (limosité endurcie). When that condition is present he suggests the use of rasps and spatumina and other instrumental means very similar to those we make use of for removing tartar.

Guy de Chauliac was also interested in mechanical dentistry and the artificial replacement of lost teeth ; and, indeed, dental prosthesis represents, as treated by him, a distinct anticipation of dental procedures usually thought quite modern.

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 44 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.

These rules are : (1) It is necessary to guard against the corruption of food and drink within the stomach; therefore, easily corruptible food—milk, salt fish, etc.—must not be partaken of, and after meals all excessive movement, running exercises, bathing, coitus, and other causes that impair the digestion, must also be avoided. (2) Everything must be avoided that may provoke vomiting. (3) Sweet and viscous food—such as dried figs, preserves made with honey, etc.—must not be partaken of. (4) Hard things must not be broken with the teeth. (5) All food, drink, and other substances that set the teeth on edge must be avoided, and especially the rapid succession of hot and cold, and vice versa. (7) Leeks must not be eaten, as such a food, by its own nature, is injurious to the teeth. (8) The teeth must be cleaned at once after every meal from the particles of food left in them; and for this purpose thin pieces of wood should be used, somewhat broad at the ends, but not sharp-pointed or edged; and preference should be given to small cypress-twigs, or the wood of aloes, or pine, rosemary, or juniper, and similar sorts of wood, which are rather bitter and styptic; care must, however, be taken not to search too long in the dental interstices, and not to injure the gums or shake the teeth. (9) After this it is necessary to rinse the mouth, using by preference a vinous decoction of sage, or one of cinnamon, mastich, gallia, moschata, cubeb, juniper seeds, root of cyperus, and rosemary leaves. (10) The teeth must be rubbed with suitable dentifrices before going to bed, or else in the morning before breakfast. Although Avicenna recommended various oils for this purpose, Giovanni of Arcoli appears very hostile to oleaginous frictions, because he considers them very injurious to the stomach. He observes, besides, that whilst moderate frictions of brief duration are helpful to the teeth, strengthen the gums, prevent the formation of tartar, and sweeten the breath, too rough or too prolonged rubbing is, on the contrary, harmful to the teeth, and makes them liable to many diseases.