Page 152 - My FlipBook

;

148 FILLING TEETH.

to make a good finish with a rough, uneven border
the filling is also more exposed to injury by mastica-

tion. The integrity of a smooth, plain surface is per-
fectly retained under influences that would break up
and destroy an uneven one. It is also very desirable
to have a firm margin; to obtain this, it is often
necessary to cut away more, than would otherwise be
desirable. A smooth, firm border should not be sacri-
ficed for the form, and especially in the posterior
teeth. It is very objectionable to some persons to
have the perfect form of the front teeth marred or

changed ; but it should be remembered that even a
front tooth, one-third cut away, and so filled as to be
permanently preserved, is far more valuable than an
artificial one.
Another particular that should always be observed,
is, to obviate all acute angles. These are seldom or
never found in proximal cavities of the molars and
bicuspids ; occasionally they are found in proximal
cavities of the cuspids, and frequently in proximal
cavities of the incisors, particularly at that part of
the cavity next to the cutting edge of the tooth.
Such angles are very often found also in crown

cavities of the molars, where there is an extension
of the decay along one or more of the fissures of the
crown.
It is difficult—almost impossible—to fill perfectly