Locating Root Canals

Locating Root Canals

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Welcome to the University of Michigan Dentistry
podcast series promoting oral health care worldwide. The objective of this sequence is that the
student will be able to locate all the canals in any tooth he is assigned in the endodontic
clinic. It seems obvious that if you donít locate the canals, you wonít be able to clean
them and fill them and the tooth that youíre treating is guaranteed to be a failure. The
instruments that are used in this procedure are simply a sterile, clean mouth mirror and
a sterile endodontic explorer. But there are also four requirements that you need to have
completed or you wonít be successful in locating all the canals. When students have trouble
locating the canals itís usually one of these four requirements that they’ve skimped on. The first is that they should have a well
designed and well-prepared access preparation especially the fact that the floor of the
pulp chamber should remain intact to guide you to the orifices of the canals. Secondly, the pulp chamber should be meticulously
cleaned of all debris. Thirdly, you should have knowledge of the
normal pulpal anatomy and where the orifices of the canals are expected to be located. And four, you should look for the maximum
number of canals in each tooth. If youíre having problems locating canals make sure
that youíve fulfilled all these four requirements and then move carefully. If you canít find
it then, youíre probably best to call over an instructor and check out your findings
with him. Now we want to go through and show you where and how to look for the canals in
various different teeth. Maxillary anterior teeth usually pose no problems to students
since thereís generally one canal coming straight off of the pulp chamber so once you
have access to the pulp chamber youíre into the canal. Mandibular anterior and bicuspid
teeth are similar in that they usually have one canal leading directly off of the pulp
chamber. However, in both mandibular and bicuspidómandibular anterior and bicuspid teeth have a tendency
to have two canals and you have to check each tooth to make sure that it does have only
one canal. You do this by coming in at different angles and looking for a second canal. Come
in heading towards the labial and have it gear right down into the pulp canal coming
from the lingual and go right on down. Feel for two canals and only accept that you have
one when youíre sure that you canít feel a second. As you can see in the cross-section diagram,
you can come in through the access preparation from the lingual heading towards the buccal,
go all the way down and the wall will guide you into a canal. If you have a second canal
when you lift the file up or the explorer and go in the other direction youíll be able
to feel a little click and the file will be going in a different direction as you slide
over into the second canal. So always check mandibular anterior and bicuspid teeth for
two canals. The maxillary biscuspids once again are usually
no problem to students. The first bicuspid usually has two canals, the second bicuspid
maxillary usually has one canal but either one could be reversed. You have to check both
teeth for two canals. You do that by once again coming in from the buccal and looking
for a canal going off to the lingual, then coming up changing the direction of your explorer,
coming down and feeling for a canal on the buccal. A cross-sectional diagram of a maxillary bicuspid
shows that if you come in from the buccal, youíll be able to goóhave direct access
right into the lingual canal. Pulling up slightly and changing the direction of the file, youíll
be able to get into the buccal canal coming in from the lingual. You check maxillary first
and second bicuspids this way to make sure that they have one or two canals. The maxillary molars present a little bit
more problem for students. You have toóyouíre farther back in the mouth and you have to
get oriented to find three sometimes four canals. This is an occlusal view of a maxillary
molar with an endodontic access preparation that has been prepared. As you can see, there
are three and then sometimes a fourth canal. The first canal is the mesial-buccal canal,
it sits almost directly underneath the mesial-buccal cusp, very much to the buccal and somewhat
to the mesial. The second canal is the mesialÖ the distal
ñbuccal canal. Students often have problems finding that because they look for it over
here underneath the distal-buccal cusp. In actuality, it is very close to the mesial-buccal
canal and it’s always lingual to the mesial-buccal canal coming off in this direction. There
is a big lingual canal uh, ómesial-lingual canal that sits underneath the big mesial-lingual
cusp. Itís almost directly lingual from the distal-buccal canal. There is sometimes a
fourth canal on this tooth. Itís considered kind of a second mesial-buccal canal that
sits one or two millimeters lingual to the mesial-buccal canal on a line drawn from the
mesial-buccal to the lingual canal so you always want to check maxillary molars especially
maxillary first molars for this fourth canal. Hereís a maxillary molar that has been sectioned
at the level of the floor of the pulp chamber. As you can see, if you leave the floor of
the pulp chamber intact during your access preparation, it will guide you right into
the canals. Comparing this section with the graphic that youíve just seen, you can see
that the mesial-buccal cuspó uh, canal sits right up here towards the buccal right underneath
the mesial-buccal cusp. The distal-buccal canal is not so far to the distal and itís
not underneath the distal-buccal cusp. But sits fairly close the mesial-buccal canal
and always lingual to it. The big lingual canal is right underneath
the mesial-lingual cusp and pretty far towards the lingual and in this tooth we have a fourth
canal, a second mesial-buccal canal. Right here. You always want to check and make sure
that you donít have one of these or if you do, you want to find it. So you have the four
canalsÖ as you can see in the graphic. Locating the orifices of the canals is only
half the battle. You have to get the files into the canals. To do this, your file has
to have the proper direction and angulation. To get into the mesial-buccal canal, you come
from the distal-lingual, down into the canal, letting the wall of your preparation and your
untouched pulp chamber floor guide you right into the orifice and into the canal. To get
into the distal-buccal, you come from theÖ the mesial, I mean mesial-lingual and you
get right into the distal-buccal canal. And to get into the big lingual canal, you come
from the buccal and youíll slide right into the lingual canal. A cross-section graphic shows you whatís
going on when we do this. You come in from the distal-lingual and youíll go right into
the mesial-buccal canal. You come in from the mesial-lingual and youíll get into the
distal-buccal canal. And if you come in from the buccal, youíll go right down into the
lingual canal. The mandibular molar poses similar problems
to those in the maxillary molar. Itís far back in the mouth and you have to get oriented
to find three sometimes four canals. Looking at this graphic of a mandibular molar with
endodontic access preparation, you can see that you have a mesial-buccal canal, located
toward the buccal right underneath the mesial-buccal cusp. The distal, I mean the mesial-lingual
canal is not that far to the lingual. Most people look for it way out underneath the
mesial-lingual cusp but itís actually almost in the center of the tooth. Then you have
almost directly distal to the mesial-lingual is the big distal canal. Now that canal sometimes
has two canals instead of one. So you have to check that canal, probing it in different
directions to look for two small canals on the distal instead of one big canal. Here is a mandibular molar that has been sectioned
at the floor of the pulp chamber. You can see that the floor of the pulp chamber guides
you right into the canals if it’s left untouched during your access preparation. Comparing
it with the graphic that we saw before, you can see that you have the mesial-buccal canal
very far up to the mesial. The mesial-lingual canal not quite as far to the lingual as you
might expect, but almost directly mesial from a big distal canal. Now in this case the distal
canal actually has two separate canals which we can find by probing in one direction and
taking the probe out and coming out and probing in another direction. Make sure in mandibular
molars that you check the distal canal to make sure that itís a single canal instead
of two smaller canals. When you find the orifice to the canal, then
you have to have the proper angulation to get your file into the canal. To get into
the mesial-buccal canal, you come from the distal-lingual, and it slides right on in.
To get into the distal, I mean the mesial-lingual, you come from the distal-buccal and youíll
get right on into your canal. And to get into the distal canal or canals, you come in from
the mesial. And if youíre checking for two canals which
you should, you come from the mesial-buccal and then the mesial-lingual. Make sure that
you only have one canal or if you have two canals that youíll find them. This graphic will show you whatís going on
inside the tooth. To get into that mesial-buccal canal, you get your file over to the distal-lingual
and itíll go right on down into the canal. You can see that it would be hard to get in
coming straight, straight down youíd hit the floor of the pulp chamber. Coming into
the distal ñ I mean the mesial-lingual canal you donít have to come all the way from the
distal-buccal because the canal is almost in the mesial of the tooth. You can come pretty
much straight on down and you’ll get right on into that mesial-lingual canal. To get
into the distal canal, you come in from the mesial, and youíll slide right on down into
that big canal. And youíll want to make sure you check for two canals in that distal. Now once again if you have any problems finding
the canals that youíre looking for, check your four requirements making sure each of
them has been fulfilled, especially the last one. Always check for extra canals to make
sure that youíre not missing any. Once youíre sure that youíve done all that you can do,
youíll want to check with an instructor to verify your results. You have been listening to a presentation
from the University of Michigan’s School of Dentistry which is dedicated to supporting
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42 thoughts on “Locating Root Canals”

  1. all those who find difficulty in root canal location n access read the book by ingle……..will clear all ur doubts n will make u confident

  2. I had a root canal on the very back tooth on he bottom left side of my mouth. Almost two months later is still feels sensitive when pressure is put on it. Why? This doesn't seem right.

  3. the reason its sensitive too pressure is because bacteria start to live on the root tips of the tooth thanks to the access to food and shelter in the canal. This causes inflammation around the roots wich you feel as them being sensitive. There can be many reasons for the tooth still being sensivitive, so you should see your dentist about it. The tooth filling can be too high, the baceria can be unusually resiliant, the rootfilling could be less than optimal etc.

  4. lol..i guess this video goes back before coronal flaring and gates glidden were considered as an essential part of endo access.. 🙂

  5. @passion1080 I'm gunna have to go with the root canal ive had two and didn't feel anything but pressure. I still fear extractions and i need 4 for my wisdom teeth :/

  6. Felt bed for my dentist that day had two root canals and 4 canals in each tooth long day for me and him. Was at the dentist for 6 hours. :/ worth it though cuz im not in pain anymore like i was.

  7. It's my first canal and my dentist took three hours to finish and now I'm in a lot of pain .. I was exhausted like her my neck is burning and when she finished I asked her did you really finished! did you really close the canal please tell me I won't come again .. I hope

  8. my first root canal treatment was easy cake lol….but my first tooth extraction OMFG lol… what a god damn pain =.= doctor had to use general anesthesia for my case

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