WANT TO pass along to you a number of tips that I think you will find especially
useful.
Test-Bending
“Breaks in your hand, not in the tooth!” It is very important
to remember to test-bend nickel-titanium instruments in your hand by bending
them 90 degrees before using them. Test-bending will reduce the likelihood
that the instrument will separate in the canal.
Rubber
Dam
The rubber dam may sometimes obscure tooth anatomy and root angulation,
making access difficult, particularly when you are hunting for thin or
calcified canals. Thus it is sometimes necessary to place the rubber
dam by clamping the tooth behind the one you are working on and then dragging
the dam forward over the tooth in front. Doing so allows you to view
the tooth in a more open field without losing the protection of the rubber
dam.
Working Length Changes
Recheck your working length with the apex locator as you instrument
and straighten a curved canal. The length will change by .5 to 1.5
mm.
Formocreosol
Here’s a new use for an old medicament. Like chicken soup, a little
“formo” couldn’t hurt. It couldn’t hurt to place a squeezed dried
cotton pellet of “formo” in the chamber and over a post prep after a one-visit
root canal. The formocreosol may help to ensure and maintain sterility
until the restorative is started.
Carbocaine
Carbocaine has a quicker onset than lidocaine, so use carbocaine before
lidocaine as a local anesthetic; then follow it up with a lidocaine 1:100,000
epinephrine injection to vasoconstrict and augment the carbocaine’s effect.
Apex Locator Readings
Using a loose-fitting file to obtain measurement control with an apex
locator can lead to an inaccurate reading. A slightly tighter-fitting instrument
that contacts the walls of the canal will allow the apex locator to electronically
read the canal better. Also a loose instrument may move too easily
as you try to obtain a reading while attempting to manipulate the stop,
thus giving you a false length.
Removing a Post
When you are trying to remove a prefabricated post, use an ultrasonic
instrument and vibrate the post in all planes (buccal-lingual and mesio-distal).
Remove Core Material
Remember to remove as much core material as possible around a prefabricated
post and try to trephine around its base with a fine diamond at the prep
orifice before you start to use ultrasonics.
Fractured Post
Use a one-half or one-quarter round surgical-length high-speed bur with
magnification to drill out a post that is fractured or not removable by
ultrasonics. Take an extra check radiograph when necessary to check your
progress.
Reduce the Core-Tooth Interface
When you are removing a cast post and core, remove as much core as you
can to reduce retention caused by the core-and-tooth interface before you
attempt ultrasonic removal. If there is a larger area of contact between
tooth and core, less of the force of the ultrasonic vibration will reach
the post-and-post-prep interface.
Tapping a Post Out
Sometimes a small notch can be cut into the core material and the post
can be tapped out with a back action crown remover. Do this
prudently because the force of the tapping can cause a root fracture.
Revealing Old Gutta Percha
If retreatment is the goal, then using a microscope and a fine Spartan
ultrasonic diamond tip may be necessary after post removal to cut through
any remaining cement at the base of the post prep in order to find the
old gutta percha.
Retreating Canals Without Posts
If only the canal or canals without the post are failing, then
you can drill through the crown and core material conservatively and retreat
these canals without disturbing the post and crown. (See Figures 1 and
2.)
FIGURE 1 (before) |
FIGURE 1 (after) |
FIGURE 2 (before) |
FIGURE 2 (after) |
Apicoectomy or Retreatment?
When a patient presents to your office with failing endodontics
under a post and core, your first instinct may be to refer the patient
for an apicoectomy. This instinct is particularly well founded when the
restorative is relatively new. However, we must remember that an apicoectomy
on top of a root canal that failed because it was inadequate may result
in a failure of the apico as well. The failure of the apico usually
occurs because lateral canals coronal to the retrograde filling were not
obturated properly. Even in the case of calcified apices or a calcified
apical third of the root, it is important to have a solid obturation coronal
to that point. Thus retreatment becomes a rational option. Also, if the
surgery is risky anatomically, such as apex proximity to the mandibular
canal or maxillary sinus in the case of maxillary palatal roots, retreatment
may be a better option. We must also take into account the possibility
of the patient’s lack of compliance and cooperation regarding the surgery
and must consider whether the patient is a poor medical risk for the procedure.
If the restorative is in question and is slated for a redo, then without
question disassembly is the treatment of choice.
The radiographs in Figures 3 through 9 illustrate
what can be accomplished.
FIGURE 3 (before) |
FIGURE 3 (after) |
FIGURE 4 (before) |
FIGURE 4 (after) |
FIGURE 5 (before) |
FIGURE 5 (after) |
FIGURE 6 (before) |
FIGURE 6 (after) |
FIGURE 7 (before) |
FIGURE 7 (after) |
FIGURE 8 (before) |
FIGURE 8 (after) |
FIGURE 9 (before) |
FIGURE 9 (after) |
November-December 2002
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