Page 257 - My FlipBook

PREPARATORY TO FILLING 241

suggested that a non-solid root - filling should be
packed sufficiently down a root to admit of the
oriiice being well sealed, and the seal (either a white
cement or gutta-percha) extended sufficiently into
the root to preserve it if the crown of the tooth is
subsequently destroyed or broken down. Canals
can generally be sufficiently enlarged to admit of
their being filled by scraping them with the Donald-
son canal cleansers, and these are far safer instru-
ments to use than drills or reamers.
Very fine canals that cannot be thoroughly
scraped out may be sterilised as far as possible,
and left unfilled. The buccal roots of upper molars,
and the anterior roots of lower molars, usually pre-
sent the greatest difficulties in this respect. Dr
Callaghan's method of applying a 50 per cent,
aqueous solution of sulphuric acid, and working
it down fine roots with suitable probes (Dr. Flagg
advises iridium-platinum and platinum-gold probes)
enables many apparently inaccessible canals to be
cleaned out and filled (" Items of Interest," April
1894).
It is difficult to apply sulphuric acid directly to
the roots of teeth—especially upper roots. If a
little cotton-wool is twisted round the probe, the
cotton is almost immediately destroyed by the acid,
and any method which causes a flooding of the
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