Against dental pains of phlogistic origin, he recommends bloodletting, purgatives, and many local medicaments, reproduced in great part from Rhazes. In cases of persistent odontalgia due to caries, he advises, as an excellent remedy, the application of opium in the carious cavity. To strengthen loosened teeth, he first employs astringents, and if these are of no use, as often happens in the old, he binds the loose teeth together and to the neighboring healthy ones, by means of gold or silver wire. In Serapion, too, we find many formulas for dentifrice powders, some of which are intended simply for cleaning the teeth, others for special prophylactic or curative purposes.[204] AVICENNA. One of the greatest luminaries of medicine among the Arabs was Avicenna (Ebn Sina). He was born in 980 son of a high Persian functionary; he lived a very adventurous life, held some very high places, and died in 1037. Among his works, the most important is the _Canon_, a book which procured him the title of “second Galen” and the still more pompous one of “prince of doctors.” A very evident proof of the immense fame which he acquired is the fact that among many oriental peoples Avicenna, even in our own days, is considered the greatest master of medicine. The anatomy and physiology of the teeth are treated by Avicenna very minutely, but nevertheless he does not teach us, in regard to these, anything new. Like Galen, Avicenna admits that the teeth continually grow, and as a proof he gives the fact of the lengthening of the teeth, which, owing to the absence of antagonists, are not subject to any pressure or friction. He gives much good advice with regard to the preservation and cleanliness of the teeth, to which he attaches very great importance; and on this point he remarks that the use of very hard tooth powders must be avoided, as these are liable to injure the dental substance. To this latter are also harmful, says the author, some narcotic remedies, employed against odontalgia. Burnt hartshorn is, according to him, a most valuable dentifrice. To remove tartar from the teeth, he indicates many remedies, and especially dentifrices of meerschaum, salt, burnt shells of snails and oysters, sal ammoniac, burnt gypsum (plaster of Paris), verdigris with honey, etc. Among the substances able to facilitate dentition, he enumerates several oils and fats, besides the brain of the hare and the milk of the bitch, and he disapproves the custom of giving to children, during dentition, hard objects to chew, in the erroneous belief that the biting of such objects is useful in facilitating the cutting of the teeth; he recommends, instead, the gums to be rubbed with the fingers. When the teeth begin to appear, he drops some oil into the ears of the child and covers its head, neck, and jaws with a plaster spread on cotton that has been soaked in oil.