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FILLING TEETH 79

left curved, but was not grooved, as the proximity
of the pulp would render this a dangerous proceed-
ing, unless the groove was made too close to the
enamel border, leading to its being damaged by
condensation of the gold. The lateral grooves were
generally deepened into little pits at the cervical
wall, and further deepened— if thought good—into
starting pits. These depressions, supplemented by
the lateral grooves, effectually prevented rocking or
displacement of the gold during its manipulation.
Many operators found it necessary to produce a
fourth wall in these cavities by uridercutting the
occlusal part, and this could generally be accom-
plished without this margin being afterwards broken
or chipped by the force of mastication ; and this
undercutting was often made easier by a dipping in
of the decay at this part.
It frequently happens, however, that the lateral
walls are frail, and will admit of little or no retain-
age being made at chis part, and they may even
slope slightly outwards. In these cases such under-
cutting at the cervico-buccal and cervico-lingual
angles, as might be necessary to start the filling,
and prevent its rocking, was resorted to, as well
as cutting the juncture of the lateral walls and
floor of the cavity into as distinct angles as possible.
The cavity was then extended sufficiently across the