Human physiology / by William Furneaux.

  • William Samuel Furneaux
Date:
1909
Catalogue details

Licence: In copyright

Credit: Human physiology / by William Furneaux. Source: Wellcome Collection.

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    the age of about seven years these milk teeth begin to be cast off, their places being taken by the permanent teeth which grow be- neath them ; and, at about the age of twelve, all have in this way given place to the permanent set, 'I'he permanent teeth of the adult number thirty-two. They consist, in each jaw, of four incisors, two canines, four bicuspid, and Crown Keck Fang Crown Keck Fang 3 4 Fig. 85. — Showing the four kinds of Human Teeth. I, incisor tooth (exterior view) ; 2, canine tooth (exterior view) ; 3, bicuspid tooth (side view showing the two cusps); 4, molar tooth (exterior view). Fig. 86. —Section of the Jaws of a Child of 6| Years, showing the Milk or Deciduous Teeth, also the Permanent Teeth in Process of Formation. di, the milk incisors ; dc, the milk canines ; <^3, and d\, the milk molars ; i\ and z’a, the permanent incisors ; r, the permanent canines ; /3 and /4. the permanent bicuspids ; wi, the first permanent molars, which have already made their appearance ; and ;«3, the second and third permanent molars. six mo/ars. The last of the molars are called the wisdom teeth; they do not appear till between the seventeenth and twenty-fifth years. The mass of a tooth consists chiefly of a hard substance called dentine or ivory (Lat. dens, a tooth). It resembles in composition the compact tissue of bone, but contains a much larger proportion of mineral matter (seventy-two per cent.), and is consequently harder. The mineral matter, like that in bone, consists chiefly of calcium phosphate and calcium carbonate ; and the animal matter may also be made to yield gelatine by boiling. In structure dentine differs from bone, as it contains no Haversian canals, lacunae, &c.,
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