6. Treatment II Flashcards
Straight line access
◦ If you look closely, everything that is in the corner of the pulp chamber where the root canal orifices are, any
obstacle has been removed
‣ This was extremely ____ in the past when we were using only instruments made from stainless steel
‣ stainless steel is not the most flexible material
‣ as the files sizes get larger, they get very stiff - made it difficult to instrument root canals
now we use ____, but it is extremely more flexible
we are also using different designs of these files
straight line access - where we can actually go straight down into the root canals and into the orifices but we are not doing it to this extent anymore
necessary
nickel titanium
Access cavity
• At the CEJ level, it is the same outline as you have it at the outside of the tooth
• In general, a pulp chamber is also somehow ____
• In this case, you have a buccal to lingual access going through the tooth, and you will find a buccal
canal in this root along that access centrally located symmetrically
• Then you will have one in the lingual aspect of the root
• The same thing if you look into a lower molar: you would typically find a ML canal, a MB canal, and
you might find one D canal
◦ But this distal canal will also be located on the central access that is going through the tooth
from M to D
◦ There will be an equal distance from the ____ to the central access and from the central access to the ____ canal
◦ There are certain symmetries there in the roots
◦ This is usually an idea where to find these root canals where you find the pulp chamber - by
looking at the symmetry of it
symmetric
ML
MB
General access shapes
• Depending on what type of tooth you will do a RCT, there are different shapes of access cavities
• This is based on the location and the number of the root canals that these individual teeth have
• We have 3 different types of access cavities:
◦ 1. ____
‣ maxillary lateral incisors, mandibular incisors, and all canines and premolars
◦ 2. ____
‣ the maxillary central incisors and maxillary molars
‣ recall what I showed you last time - a picture of a maxillary central access cavity (which you have
to repeat a lot for the CDCA exam)
• you have to extend it and make it triangular towards the incisal edge of the tooth because
you want to make sure that you incorporate all the pulp horns into your prep and your access
cavity isn’t leaving anything behind
• because you have to take these pulp horns into the prep, that’s why you have to do the
triangular b/c this is what the root pulp chamber looks like for these teeth
◦ 3. ____
‣ mandibular molars
oval/ovoid
triangular
rectangular
Access burs
• There are also different burs that you could use if you are preparing an access cavity
• you will start in the beginning using a ____
• later, when you find your access cavity, you can take a ____ diamonds to refine the
access cavity
• in the beginning, I don’t want you to start with the conical diamond because it’s very aggressive ◦ It will be easy to perforate something on the side or the floor fo the pulp chamber
• the safest in the beginning is just to find the pulp chamber
◦ with a round bur, you can identify and find it
◦ then you can refine the access cavity later on with the conical diamond
• the reason you want to refine is b/c you don’t want to leave rugged borders and walls of the access chamber
◦ you can’t really make a plain nice wall with a round bur
round bur
straight conical shaped
Max anteriors
• What you see here is an extension to what we talked about before in terms of the length of the typical roots but also how many root canals you would find in any particular group of teeth
• Here we are also looking at the typical shape of a root canal from a labial/facial point of view and also from a proximal point of view
• this is something that you normally will not see when you do your clinical treatment with a patient
• When you’re taking a radiograph, you will always see a facial view of a tooth from a mesial to a distal direction,
but you can never really take an x-ray of a tooth from the side
• you never really know the extension from ____ of a pulp chamber or a root canal
• This is something that we have identified as one of the problems of cleaning out canals b/c a lot of root canals
are not just round, they are ____ or long-oval
◦ Oval extension of these canals is in a B-L direction
B to L
oval
Max anterior
• If you were taking a picture from a proximal view, then you would realize that maybe you ____ certain portions of the root canal b/c the extension and width from a B-L dimension is larger than from a M-D direction
◦ That is why in the lab when we are doing the exercises on the extracted teeth, we will take x-rays from the
regular direction, but we will also take a proximal shot - which is something we cannot normally do
◦ we will get that info for better understanding what is looks like
unfilled
Max anterios
◦ THE STRATEGY: whenever you do an access preparation in an anterior tooth, you just hit the root canal space and the pulp chamber and then you have to remove a little bit of ____ here in this area
◦ Then you can bring a file that comes from the ____ direction, over exaggerated, into the tooth and make it more upright and actually go down into the root canal
◦ For most of these teeth, there will always be a slight bend of the file to get into the root canal
‣ so you cannot get a ____ because otherwise you’d have to go through the incisal
edge
‣ if the tooth gets a crown later on, then you could do that and do the regular access prep through the
incisal edge
‣ but if you want to keep the enamel structure, then you cannot do that and you have to have these
precautions
dentin
lingual
true straight access
Max premolars
• All of the premolars will have an oval/ovoid access cavity
• we always think of finding at least ____ canals in the premolars
• in the past, second max PM thought to only have 1 root canals
◦ But about 50% of max second PMs will have ____canals
• We always have to prepare an access prep as if we are looking for those 2
• That’s why it’s an oval access cavity - one in the B direction and one in the L direction
• Max 1st PM very often have 2 canals
◦ but about 5% of time find ____ canals
◦ Then they look like a mini molar
◦ 2 ____ canals - usually split somewhere right below the orifice ◦ then you have a larger palatal root canal
• the same for the 2nd PM but the incidence is only about 1/100 for ____ root canals
• you may not see this when you’re doing RCT, but this is something we use a microscope for the
instrumentation to see what we’re doing
• Can see on some of the pictures that there are very deep pulp chambers, and they seem to be splitting
further down than just at the floor of the pulp chamber where it comes straight out of the pulp chamber into
the actual root canals
• these are all variations that we may find
• Some can be very difficult
• You will see all these variations with different classifications and some of the mixed forms
2 2 3 buccal 3
Max premolar
• (This is actually a 3 canal PM here)
◦ they are ____
◦ there are 2 buccal and one lingual
shorter
Max premolars
Root walls are ____
Roots taper rapidly to ____ Proximal root ____
____ canals
thin
apex
invaginations
multiple
Max premolars
• You have to have a precaution in these maxillary premolars because the roots can be very thin in a ____ direction
• If you heard Dean Wolff talk, he said he didn’t know why people still do RCT on maxillary PMs
◦ Setzer says because in the past, ppl have used very large RC preparations that open a lot in the cervical
area of the root, weakening the root structure a lot
◦ there were a lot of cases were roots were fracturing after a year, 5 yrs, because the occlusal forces were
too much and the root structures were weakened
◦ This is due to the fact that we have these ____ root structures in the MD direction
‣ they are very shallow plus they have this ____ proximally mesial and distal
‣ this makes it very dangerous that we might ____ somewhere in these areas when we do
our root canal instrumentation
‣ you have to be aware of it when you drill too deep into those canals that you might reach an area of
the root where it’s very thin from M-D in the central aspect if this is one root
‣ the tooth might also have ____ roots, that’s also common
‣ but often we see this one root with 2 root canals and this typical indentation from a mesial aspect
• something we find on the first max PM
tiny
indentation
perforate
2
Man anterior
• These are mandibular central and lateral incisors
• some of the most difficult to do a RCT on
◦ because very small
◦ need a very tiny access prep
◦ need to find tiny canals
◦ have to have same precautions not to perforate in a cervical aspect because (again) have to come from
the lingual aspect of the root
◦ ovoid access cavity prep
• there is one thing that makes it very difficult to treat lower incisors:
◦ there is very often (40% of them) have ____ root canals
◦ normally don’t associate w/ lower incisors
• people only find one root canal because when you come from the lingual and get into root canal system, you
automatically always dive into the ____ of the 2 canals
◦ when you instrument, you create debris and you ____ that entrance to the lingual canal, close with dentinal debris, and you might not find it
◦ This is where a microscope comes in handy b/c can look into dark portion of root canal and identify if
there’s a second canal we might have missed
◦ this is something we might find in central and lateral mandibular anteriors
• Mandibular canines - also see variations and the different shapes of these root canal systems
◦ oval access cavity - not as difficult to treat as a PM or incisor
• The biggest difficulty w/ the canines is that sometimes they can be very ____
◦ not uncommon that we find a canine that are longer than 30 mm
◦ We have seen cases up to 40!!
◦ sometimes have to shave down tooth to be able to do root canal instrumentation
◦ we have files that you can use usually 25 mm, but for the canines have 31 mm that you can order and
work with
2
buccal
smear
long
Man anteriors
Proximally ____ roots
Proximal ____ in root
Roots narrow in ____ half
____ canals
This is a summary for the mandibular anteriors
In interproximal direction - very thin roots
There’s also an invagination, and the roots are very narrow in the apical half and there can be multiple canals
thin
invagination
apical
multiple
Man premolars
• These are considered one of the most difficult teeth that you can treat
• many of them are simple, but many of them are also extremely difficult b/c have a high number of
variations - particularly in the ____
◦ about 30% of them have 2 or 3 canals, and it’s not just that they have a buccal canal and a lingual
canal like in max PMs, it’s typical that the split into a buccal and lingual canal is several mm down
into the root canals below the floor of the ____
◦ this makes it extremely difficult to find the split and instrument the buccal and lingual canal (or if
there are 2 buccal canals and 1 lingual canal)
‣ just like a mini molar that we can have
mandibular 1st PM
pulp chamber
Maxillary first molar
\_\_\_\_ Canal in 80-95% (depending on literature) MB2 (71.2% two separate canals) \_\_\_\_>MB2 \_\_\_\_ often covered by dentin
the most notorious of these is the 1st maxillary molar
◦ b/c in the MB root, there is a ____ canal (an MB2) that many ppl struggle w/ to identify
have 3 roots - a MB, a DB, and a palatal root
◦ ____ root usually has largest canal - not difficult to find
◦ typically most of the cases (3/4) have a 2nd ____ canal
‣ the 2nd one is ____, more ____ and more hidden from the entrance
‣ much more difficult to instrument b/c the canal is thinner and often calcified
4th
MB1
MB2
second palatal MB smaller calcified
Here’s an example of 2 separate canals inside the MB root
This is a cross section of an extracted tooth
What you see here is the ____ canal (larger) and MB2 canal that is smaller
can see typical shape in cross section that these teeth have
This is something that might be wider in the ____ dimension on the buccal aspect of the MB and thinner on the ____ aspect
◦ this is something that might cause a problem b/c could lead to a ____ where the root is very thin ◦ if you were instrumenting too large in regard to the diameter of the root
◦ generally do not have this problem for the ____ and not at all for the ____ root b/c have sufficient tooth structure for instrumentation
MB1
MD
palatal
perforation
DB
palatal
• This is a picture where someone was doing an access cavity prep and didn’t explore the root canal orifices at that time
• can see MB aspect, DB aspect, and a palatal entrance
• There’s a small indentation in this dentinal area
◦ this is typical for the appearance for how an ____ canal is hidden for when we do access prep into tooth
• we open this up (picture on right), and we instrument this, remove overhanging dentin to gain free access to root canal
• after this is instrumented, you will see how it’s clean and larger
◦ there was a lot of dentin masking and covering the entrance of the root canal
◦ doesn’t mean it was dentin all the way down - there is a very shallow portion of pulpal tissues b/w that dentin and the entrance of the root canal
◦ can see how much the root canal entrances are going to be relocated towards the ____ of your access prep b/c when you prepare root canal and you’re creating straighter access, you’re moving towards periphery outwards
◦ when you enlarge a root canal, you automatically translocate this into the ____ direction, actually straightening out root canals
◦ if you have a canal that’s very curved and you start instrumenting and make larger, we actually straighten out a little bit
‣ what this means is that when you instrument and we have to find how long to make our root canal prep, before we fill the
tooth, we have to check it one more time b/c we might have straightened it
Penn
MB2
periphery
buccal
The road map
using the ____ as a guideline to canals
a typical length for an instrumentation molar is ____ mm from a reference point to a cusp on the tooth to the end of our prep in the root canal
◦ even if we measure 19 in the very beginning, this may become ____ (typically lose 0.5 mm) throughout length of your prep
◦ because you make it larger and straighten it slightly - more direct way to apical area and have to adjust to this so don’t puncture at end of root or overfill in PA tissues
“The Road Map”
◦ the floor of the pulp chamber typically looks ____ than the dentinal walls surrounding the access cavity
‣ see more on right picture
‣ but if you’re looking to floor of pulp area, it’s dark brownish
◦ you also see a line (in blue) - what we call the road map
◦ these are ____, and can use those to find other root canals
◦ these lines on floor of pulp chamber connect the main canals
◦ you can see that there’s some sort of connection between them, and if you follow and trace them then you would find the orifices of the other canals
◦ can follow to find other canals
pulp floor
19
shorter
darker
developmental lines
Maxillary second molar
Similar Anatomy as 1st maxillary molar, more variations, less ____
• These are very similar to a max 1st molar BUT everything on these teeth, if you compare a patient’s 2nd max molar to the 1st max molar, is shorter in a ____ direction
• everything on these teeth from the M aspect of the crown to the D aspect of the crown in a second max molar is shorter than in the 1st molar
• the pulp chamber will be shorter
• This is the MD direction and not the BL direction
◦ what this looks like is everything you had on the 1st max molar and you squeezed it in a MD direction
◦ then you get shape of pulp chamber, orientation of root canal orifices, overall dimension of the 2nd maxillary molar
• triangular access cavity
• may also find ____, but it is less common than in 1st max molar
• similar anatomy, but is squeezed together
MB2
MD
MB2
Max second molar
- can see with microscope he is finding less of ____ canals in comparison to first max molar
- before he found b/w 80 and 90
- here finding b/w 50 and 60 without the microscope, with the microscope
- It’s nowhere near the numbers you have for 1st max molar
- but may find them and if you treat any of those teeth have to be careful not to miss any of those canals
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