Hand-book of physiology / by W.D. Halliburton.

  • Halliburton, W. D. (William Dobinson), 1860-1931.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: Hand-book of physiology / by W.D. Halliburton. Source: Wellcome Collection.

    99/886 (page 71)
    From tins formula it will be seen that the two bicuspid or pre- molar teeth in the adult are the successors of the two deciduous molars in the child. They differ from them, however, in some respects, the temporary molars having a stronger likeness to the 'permanent than to their immediate descendants the so-called bicuspids, besides occupying more space in the jaws. The temporary incisors and canines differ from their successors but little except in their smaller size and the abrupt manner in which their enamel terminates at the necks of the teeth, forming a ridge or thick edge. Their colour is more of a bluish white than of a yellowish shade. The following tables show the average times of eruption of the Temporary and Permanent teeth. In both cases the eruption of any given tooth of the lower precedes, as a rule, that of the corresponding tooth of the upper jaw. Temporary or Milk Teeth. The figures indicate in months the age at which each tooth appears. DECIDUOUS DECIDUOUS INCISORS. FIRST CANINES. SECOND MOLARS. MOLARS. 6 12 18 24 Permanent Teeth. The age at which each tooth is cut is indicated in this table in years. FIRST MOLARS. INCIS CENTRALS. ORS. LATERALS, BICUSPID MOL FIRST. 3 OR PRE- ARS. SECOND. CANINES, SECOND MOLARS. THIRD MOLARS OR WISDOMS. 6 7 8 9 10 II 12 17 to 25 The times of eruption given in the above tables are only approximate : the limits of normal variation being tolerably wide. Certain diseases affecting the bony skeleton, e,g.^ Rickets, retard the eruptive period considerably. It is important to notice that it is a molar which is the first tooth to be cut in the permanent dentition, not an incisor as in the case of the temporary set, and also that it appears behind the last deciduous molar on each side. The third molars, often called Wisdoms, are sometimes unerupted through life from want of sufficient jaw space and the presence of