1st step for root
mapping is pre-operative radiographs. Must be taken with multiple shifts. It
helps in identification of extra anatomy. Pre-access analysis (biominimalistic
approach).
So the importance of preoperative radiograph is:
Prevention of mis-haps.
Point of entry & curve assessment.
Identification of extra anatomy. Radix entomolaris is an extra root, found
in a high percentage in lower 6 and sometimes lower 7.
-2nd step is CBCT. Not
in all cases.
It can spot resorptive defects with multiple portals of exit.
Can be used in cases with calcification.
Micro guided endodontics: CBCT guided, it’s accurate, fast and operator
independent method.
2)Canal location:
-Knowledge alone is not enough.
-Explore unfamiliar pathways.
-Guide file / patency file:
the file I use to take my 1st radiograph. If it’s not centralized,
shifted mesially or distally, expect there’s extra canal or extra portal of
exit.
You can take one shift during w.l determination and the other one on master
cone fit to reduce x-ray dose.
-Sudden break:
it’s immediate
disappearance of canal space indicating the presence of apical split. That
split has a very narrow entrance, if you made heavy pressure, you’ll block it
with dentin chips and lose its patency. So, working length should be taken just
to the entrance of the split. Then, pre-curve the apical part of your file and
start filing in a rotation movement with minimal apical pressure after coronal
flaring.
-Double / twin lamina dura:
it
indicates that the root is very wide in bucco-lingual direction. When you see
this, you have to expect there’s extra anatomy.
-Clinical tips:
-Ultrasonic: it’s mandatory in your work nowadays. It’s essential to find
extra anatomy.
-The percentage of trifurcated
premolars in Egyptian population is 33%.How to spot?
Wide buccal gingival contour.
In radiograph, there’s very wide buccal root.
On access, there’s non-stopping bleeding from the buccal canal.
-It may be sub-chamber furcation
(one orifice then 2 canals), or at the middle 3rd (very deep
furcation).
-Color change of the pulpal floor:
it’s very important not to use
any end-cutting stone on the floor after opening access not to lose endodontic
/ dentin map.
-Isthmus cleaning: any single root with more than 1 root canal should have a
connection between them. If this connection is coronal, remove it with
ultrasonic tip to spot any extra anatomy. If there’s no extra anatomy, then at
least you cleaned this area from pulpal tissue that may act as a nutrition to
the bacteria after wise.
-MB2: to find something, you’ve to believe it’s there. MB2 is 96%
present. It’s located at the end of an imaginary line drawn from the distal
canal and perpendicular to another line drawn between the palatal and MB1
canals.
-Can be found through ultrasonic
or modified gates gliden troughing. You can cut the end of gates to make it
non-cutting end, and use it in a lateral motion to remove white dentin shelf
till a black spot appears. Never increase vertical pressure not to make a
ledge.
3)Scouting & patency:
-Till now, we’re just preparing canals to start shaping.
-Patency: it’s a safe
passage for the file from orifice to portal of exit. We should proceed until we
meet resistance or reach the working length.
-For patency we have file & motion.
-The file should be short,
because it gives better tactile sensation & complete authority over the
file.
-The motion is watch-winding
action with minimal pressure and you’ve to be patient.
-Dentin mud / calcification / apical blocking: here you need to use smaller
instrument, but you may face a problem that it bends when you introduce it into
the canal, so, you’ll need to change the material from stainless steel to
carbon steel (c+ files from dentsupply or canal locators from poldent).
-Supported patency: when you support the shank of the file with your finger
while watch-winding to protect it from bending.
-New files have sharp tips, in these cases, we need dozens of new files,
each one will be used in 3 strokes of push & pull, after 3 strokes
sharpness decreases and you’ll need new one, so these cases are called files
eaters.
-You’ll need NaOCl showering.
-Never use EDTA when your canal is not patent.
4)Working length:
-Apex locator and radiographs.
-Both are indispensable.
-You can’t take solid information from radiographs. Because different shifts
give different information. So, it’s illusive.
-Apex locator is technique-sensitive.
-Any metallic restoration in pulp chamber shouldn’t be touched with the
file, either by removing it or covering file shank with Teflon.
-Extreme exudate or acidity gives false readings.
-Wet pulp chamber gives false readings (sometimes reading of another canal).
-It’s better to take w.l after coronal flaring (moist canal but not wet).
-Don’t depend on readings when the apex locator is flashing intermittently
(up and down reading).
-Depend on the reading when the apex locator is proceeding as the file is
proceeding into the canal.
-You should retake your w.l before apical 3rd preparation.
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