Against periodontitis and the pains produced by it, he sometimes had recourse to bleeding. He commended, besides, opium, oil of roses, pepper, and honey, and also the scarification of the gums and the application of a leech. If, however, these remedies did not succeed, he applied his theriac, which was composed of castoreum, pepper, ginger, storax, opium, and other ingredients, to the roots of the teeth. If even this method of cure failed, he touched the root of the diseased tooth with a red-hot iron, or sought to provoke its fall by the use of special medicaments, such as coloquintida and arsenic (a substance to which he had recourse, particularly in those cases where there was ulceration of the gums). It is no wonder that such means of cure would sometimes produce, as a final result, the actual falling out of the tooth; and this, as is natural, served to strengthen the belief that the same result could also be obtained with less energetic remedies, but which were supposed to be equally endowed with expulsory virtues. Rhazes relates an interesting case of regeneration of a whole lower jaw; he, however, observes that the newly formed osseous mass was less hard than the original bone.[201] ALI ABBAS, another great Persian physician (who died in 994), wrote a lengthy treatise on theoretic and practical medicine, one chapter of which is dedicated to the diseases of the teeth. When a molar tooth is affected by caries, and the pain cannot be subdued in any other way, Ali Abbas applies, inside the carious cavity, the end of a small metallic tube, into which he repeatedly introduces red-hot needles, leaving them in the tube until quite cooled. Should even this have no effect, he tries to provoke the fall of the tooth by the application of asses’ milk with assafetida, or, finally, extracts it.[202] He cures epulis, like Paul of Ægina, by excision. As to parulis, or abscess of the gums, he opens it with a lancet or a wooden stylus. When the dental arch is deformed by the existence of supernumerary teeth, he removes these with an instrument in the shape of a beak.[203] SERAPION (Jahiak Ebn Serapion), who lived in the tenth century, and up to the beginning of the eleventh, contributed but slightly to the development of medicine and dentistry, as he was in his writings little more than a mere compiler. He indicates with great precision the number of dental roots, and expresses an opinion that the upper molars have need of their three roots in order to keep firm in spite of their pendent position, whilst two roots alone are sufficient to keep the lower molars in place, on account of the support which they receive from the jaw. Serapion, like Galen, admits the nutrition and continual growth of the teeth—a growth which is produced in the same proportion as the waste due to mastication—and he too makes the dental diseases depend upon an alteration in the nutritive process, either by excess or by defect.