Methods of filling teeth : an exposition of practical methods / by Rodrigues Ottolengui.

  • Rodrigues Ottolengui
Date:
1891
Catalogue details

Licence: Public Domain Mark

Credit: Methods of filling teeth : an exposition of practical methods / by Rodrigues Ottolengui. Source: Wellcome Collection.

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    bluish color which occasionally is seen around an apparently perfect filling. If it is denied that a filling cannot be made water-tight, it is still to be remembered that in filling this labial undercut, even thus imperfectly, the strain as in the case of the palatal aspect would prob- ably crack the thin enamel. The subsequent loss of even a tiny particle of enamel would give sufficient entrance for fluids into this artificially-produced lacuna. If, in addition to this, the excavation had not been thorough and just a little caries were left, it would require no gray-beard to explain the blueness. In Fig. 7 we have an approximal surface occupied by a filling which thus indicates the outlines of the orifice of the cavity. Fig. 8 is placed in juxtaposition, and lines are drawn through the two for comparison. The latter is a longitudinal section through the greatest diameter of the filling, the approximal portion having been thus re- moved. By comparing the lines a, a in the two figures, it is seen that the undercut toward the cutting-edge is very slight. Any great extension in this direction is not only unnecessary but endangers the corner of the tooth, already weakened by decay. Comparing the lines b, b, it is seen that this portion of the cavity is extended much beyond the border. Also observe that this extension takes the form of horns, conforming in shape with the imaginary line e, e, which rep- resents the gingival border of the enamel. By proceeding thus it is plain that we leave the enamel at the gingival border of equal strength, • whereas if with a rose bur we cut a groove connecting the horns f we gain nothing in retentive strength, while by thus undermining the enamel unequally we leave it weak dXg. In malleting gold against this border the greatest strain will be against the weakest point, g, because of unequal resistance, probably producing a crack or fracture, which readily explains in one way the oft-noticed recurrence of caries at the gingival borders. By comparing the lines c, c, the labial borders, it is seen that a slight extension, or groove, exists along the full extent, de- creasing toward the cutting-edge. The lines d, d, however, indicate that the lingual borders are identical, except at /z, where there is a decided dip. Along the lingual portionr of an approximal cavity (in the six anterior teeth) it is usually safer to make no groove except at the upper third, where the thickening of the tooth gives sufficient dentine for a deep dip, which will add great retentiveness to the cavity. Fig. 9 is important. It is a section through an incisor and filling, the labial half being removed. At a glance it is seen that on this plane the cavity has no retentive shape whatever. This is because on this plane, which is through the center of the pulp, extensive undercutting would either approach the pulp, or produce weak points in enamel. The gingival border at g is seen to be strong, and shaped to resist any necessary force which may be brought against it. Were the
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