[Vesalius' Fabrica and the anatomy of the masticatory system]

In this Tabulae sex, Vesalius does not dare contradict Galenus views too definitely: in the upper jaw he counts fifteen bones amongst which the Os intermaxillare, and two bones in the Mandibula. In the Fabrica, he maintains the unity of the Mandibula; he denies the presence in man of the Os intermaxillare and counts in the upper jaw twelve bones (amongst which the Os planum). He denies the existence of the Vomer and the lower nose-shells. He gives a lyrical description of the Sinus maxillaris, but without an evident image. The under-jaw is moved by four pairs of muscles, which he does not name but numbers. The Musculus pterygoideus lateralis is not described. Jaws, tongue and teeth are tended, not by the Nervus trigeminus, but by the third and fourth pairs of the seven "brain nerves". The thirty-two teeth are divided into "cutting-teeth", "eye-teeth" and "molars", but, with their roots they are pictured in a wrong occlusion. Vesalius declares more than once, that he discovered the pulp-chamber and also the chamber of the smaller bones and concludes hereby that teeth have got all the characters of bones. They consequently are made of only one substance. Their chamber lies as far of the chewing-surface as of the summit of the root and is filled with a kind of marrow. Blood-vessels and nerves penetrate into the side of the hard substance of the hidden part. Vesalius does not make any difference between milk teeth and the permanent dentition. Just like a long bone, a tooth possesses a diaphysis and an epiphysis, for which he uses the word "appendix". In both cases the two parts only join at the end of the growth. When about seven years, the "appendices" fall out, they are replaced by their "diaphyses". If this does not happen, for instance in the big molars, diaphysis and appendix grow firmly together. Vesalius' therapy for early caries is surprising. If, in a child a permanent tooth gets injured, and if only the crown is removed, the tooth is replaced by a "new" tooth.