A system of dental surgery / by Sir John Tomes.

  • John Tomes
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: A system of dental surgery / by Sir John Tomes. Source: Wellcome Collection.

    66/808 page 50
    from that of the permanent set in being perfectly vertical. The crowns do not occupy a more forward position in the dental circle than their respective roots ; the crown of each tooth is directly over or under (as the case may be) its own root, the latter standing immediately in front of one or other of the successional teeth. On removal of the bone from the anterior surface of the maxilla, it will be seen that the permanent central incisors are placed nearlj^ parallel with each other, the cutting edges in the upper teeth being inclined a little forwards, while the parts corresponding to the base of the crowns of the two teeth respectively are placed immediately below the floor of the nose, from which cavity they are separated by a thin layer of bone only. The teeth at tliis stage of growth com- pletely fill the cells or crypts. The corresponding lower teeth hold a similar position in the lower jaw, but have a strictly vortical position, and show a slight advance in development as compared with the upper centrals. The lateral incisors of the upper jaw have a slightly oblique direction, the cutting edges being more forward than the base of the crowns, which are nearly on a level with the corresponding parts of the central teeth. The labial surface of each is often slightly turned, so that the mesial surface which lies against the central incisor is directed outwards, while the mesial angle of the tooth stands in front of, and a little over the contiguous portion of the central incisor. The point at which the one tooth overlaps the other, corresponds to the position of the root of the temporary lateral incisor. Tliat side of the lateral which in the perfected teeth lies against tlic canine, here rests against the cell which contains the first bicuspid; while the developing canine is at this period above the latter tooth. In the lower jaw the lateral incisors are placed less regularly, holding a position slightly more back- ward than the centrals. The tooth on either side is turned from the median line, and lies obliquely over the canine, to the extent of about half of that tooth. They do not, how-
    digitised image 1
    digitised image 2
    digitised image 3