Principles and practice of filling teeth / by C.N. Johnson.

  • Johnson, Charles Nelson, 1860-1938.
Date:
1902
Catalogue details

Licence: Public Domain Mark

Credit: Principles and practice of filling teeth / by C.N. Johnson. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    than in the ordinary contour filling. The advantage of this form of anchorage mnst appeal to every mechanical mind. A filling properly placed in such a cavity cannot be dislodged short of frac- ture of the filling or stretching of the gold from repeated impacts of the lower tooth at the point where the main body of the filling joins the step. Stress brought to bear on such a filling in the process of biting has a tendency to force the filling into the cavity instead of lifting it away, as in the usual methods of anchorage. Detail of Cavity Formation. The same general plan of formation is followed in the gingival third of the cavity that was advocated for simple proximal cavi- ties, except that the anchorages may be made deeper, and if pos- sible broader, for the contour filling. The labial wall. This wall should be fonned as nearly as possi- ble at definite right angles with the axial wall. The creation of an angle at this point is a matter of importance in all cases where the Fig. 41. Fig. 42. Fig. 43. Fig. 44. Fig. 45. Fig. 46. extent of the labial wall will permit it. The direction of stress against these fillings by the lower incisors is often obliquely up- ward and toward the labial (Fig. 44), and the broader we can make the area of resistance to this stress the more securely will we retain the filling. The open aspect of these cavities renders the adapta- tion of gold into such an angle very convenient. The labial wall of the step should have the same form and same angle between it and the seat of the step or pulpal wall. This portion of the labial wall should be left as thick as possible to prevent the gold from showing through and to represent considerable strength. In those