Page 251 - My FlipBook

PREPARATORY TO FILLING 235
sists in a possible or probable weeping in of the
exudations of the tissues surrounding the root near
the canal through the apex, and a consequent
decomposing of this exudation in the canal, A
solid root canal -filling is supposed to entirely
prevent this, and it also prevents the far more
likely, and consequently far more serious, filling
up of the canal with decomposable substances, if
the filling of the tooth proper fails, and the
canals in consequence become exposed. There
is no doubt that solid root-fillings have enabled
many roots to be successfully crowned after loss
of fillings from subsequent decay, that would have
otherwise become so infected and decayed that
extraction would have been resorted to. Theo-
retically and practically, therefore, root-fillings
of a solid kind are useful. As against this, we
have to consider the uncertainty of knowing the
condition of the peridental membrane, and it is
safe to presume that a peridental membrane that
has once been severely damaged may at any time
give trouble. It is well known that venting the
canals is not only the promptest but often the only
means of relieving peridental trouble, and it is also
well known to those who have been long in practice
that a re-treated canal will often enable a tooth
to be comfortably retained. Now the venting and