Descriptive anatomy of the human teeth / by G.V. Black.

  • Greene Vardiman Black
Date:
[1897]
Catalogue details

Licence: Public Domain Mark

Credit: Descriptive anatomy of the human teeth / by G.V. Black. Source: Wellcome Collection.

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    25. The mesial (Fig. 7) and distal surfaces present the characteristic V-shape of all the incisors. From labial to lingual the mesial surface is rounded near the cutting edge, but much flattened near the gingival line. Sometimes a slight concavity exists at this point. Occasionally the mesio-labial angle has a flattened or sunken point of enamel near the mid- dle of its length. This is sometimes broad and of notable depth, and in this case is generally in the labial portion of the mesial surface. In others, it is a small imperfection in the mesial margin of the labial surface. The distal surface is con- vex in all directions. In its incisal third, it rounds out freely toward the cuspid, but becomes more flattened toward the gin- gival line. 26. The lingual surface (Fig. 8) of lateral incisors, is very irregular in the extent of its concavity. Some are almost flat, while others are deeply concave. The mesial and distal marginal ridges are proportionately broader and stronger than in the centrals. In the majority of examples the lingual sur- face is the broadest part of the crown. The rounding of the proximate surfaces is at the expense of the labial surface, so that a moderately acute angle is formed by the junction of the proximate surfaces with the lingual. Generally, the lingual surface is almost smooth, but in many, a pit, with or without lateral fissures, will be found at the junction of the lingual sur- face proper, with the linguo-gingival ridge (Fig. 9). I11 some of these, the linguo-gingival ridge is unusually short, so that the marginal ridges are folded in together at their gingival ends, forming a deep sulcus between them, and there is a deep pit at their junction. Again, some are found in which there is a deep groove, which is often fissured dividing one marginal ridge from the linguo-gingival ridge, and extending into the cementum (Fig. 10). This’is sometimes nearly central, giving the appearance of a failure of the lingual lobe, or of a division of the lobe centrally, or of the displacement of the lobe to one side. This is the linguo-gingival fissure. 27. The root of the upper lateral incisor (Figs. 6 to 11)
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