ROOT CANAL
ACCESS OPENING OF ANTERIORS
A. Entrance is always gained through the lingual surface
of all anterior teeth. Initial penetration is
made in the exact center of the lingual surface at
the position marked “X.” A common error is to
begin the cavity too far gingivally.
B. Initial entrance is prepared with a round-point
tapering fissure bur in an accelerated-speed contra-
angle handpiece with air coolant, operated at a
right angle to the long axis of the tooth. Only
enamel is penetrated at this time. Do not force the
bur; allow it to cut its own way.
C. Convenience extension toward the incisal continues
the initial penetrating cavity preparation.
Maintain the point of the bur in the central cavity
and rotate the handpiece toward the incisal so that
the bur parallels the long axis of the tooth. Enamel
and dentin are beveled toward the incisal.
Entrance into the pulp chamber should not be
made with an accelerated-speed instrument. Lack
of tactile sensation with these instruments precludes
their use inside the tooth.
D. The preliminary cavity outline is funneled and
fanned incisally with a fissure bur. Enamel has a
short bevel toward the incisal, and a “nest” is prepared
in the dentin to receive the round bur to be
used for penetration.
E. A surgical-length No. 2 or 4 round bur in a
slow-speed contra-angle handpiece is used to penetrate
the pulp chamber. If the pulp has greatly
receded, a No. 2 round bur is used for initial penetration.
Take advantage of convenience extension
toward the incisal to allow for the shaft of the penetrating
bur, operated nearly parallel to the long
axis of the tooth.
F. Working from inside the chamber to outside, a
round bur is used to remove the lingual and labial
walls of the pulp chamber. The resulting cavity is
smooth, continuous, and flowing from cavity margin
to canal orifice.
G. After the outline form is completed, the surgicallength
bur is carefully passed into the canal.
Working from inside to outside, the lingual “shoulder”
is removed to give continuous, smooth-flowing
preparation. Often a long, tapering diamond point
will better remove the lingual “shoulder.”
H. Occasionally, a No. 1 or 2 round bur must be used
laterally and incisally to eliminate pulpal horn
debris and bacteria. This also prevents future discoloration.
I. Final preparation relates to the internal anatomy
of the chamber and canal. In a “young” tooth with
a large pulp, the outline form reflects a large triangular
internal anatomy—an extensive cavity that
allows thorough cleansing of the chamber as well
as passage of large instruments and filling materials
needed to prepare and fill a large canal. Cavity
extension toward the incisal allows greater access to
the midline of the canal.
J. Cavity preparations in “adult” teeth, with the
chamber obturated with secondary dentin, are
ovoid in shape. Preparation funnels down to the
orifice of the canal. The further the pulp has receded,
the more difficult it is to reach to this depth
with a round bur. Therefore, when the radiograph
reveals advanced pulpal recession, convenience
extension must be advanced further incisally to
allow the bur shaft and instruments to operate in
the central axis.
K. Final preparation with the reamer in place. The
instrument shaft clears the incisal cavity margin
and reduced lingual “shoulder,” allowing an unrestrained
approach to the apical third of the canal.
The instrument remains under the complete control
of the clinician. An optimal, round, tapered
cavity may be prepared in the apical third, tailored
to the requirements of round, tapered filling materials
to follow. The remaining ovoid part of the
canal is cleaned and shaped by circumferential filing
or Gates-Glidden drills.
PLATE 3
Endodontic Preparation of Maxillary Anterior Teeth
