Hi everyone, I'm Prateek, a dentist and specialty doctor and in this video we're going to look at how to
effectively carry out a radiographic assessment of a lower wisdom tooth. If you want to see similar
educational content to this, please make sure to subscribe to the channel. By being able to
effectively assess and evaluate a radiograph of a lower third molar, we are able to inform our
patients more accurately about their clinical scenario, it increases our confidence when it
comes to the surgical procedure and it also helps us identify and predict potential complications.
Identifying and predicting complications is extremely important. If we identify it early on and we almost
predict to the patient that this is a risk of happening, when it does happen the patient
understands because we've warned them. However, if we don't warn the patient of a potential risk or
complication, when it comes to it happening they think we're making excuses about what's happened.
Effectively assessing a radiograph isn't just for those who are removing the teeth. It is also
important for you if you're considering referring a patient for onwards care because you have a duty
of care towards the patient to identify risks and warn them of it and also explain why you're
referring them in the first place. Additionally patients may just have questions about what
risks are involved and so it's helpful for you to be able to assess their radiograph and tell
them risks that are relevant to them. So when it comes to assessing lower third molars whether
it's on periapical radiographs or OPTs, whatever it may be, a mnemonic that I like to use is CRAP.
So if we break this down, we have C that reflects the crown of the tooth. So I look at the crown and
see is there any caries, any restorations present. Because something like caries will significantly
weaken the crown of the tooth and therefore is liable to fracturing during extraction. Also
under crown, I look at the morphology of the crown so does it look particularly bulbous, an abnormal
shape, anything that may affect the extraction. I then move on to R which is looking at the roots.
So how many roots does the tooth have? Are they developed roots? Are they ankylosed roots?
Are there any particular abnormalities with the shape or morphology of the roots? So are there
any bends, any hooks in the roots, any bulbosities because all of these factors may increase the
difficulty in extracting the tooth at the end. We then move on to A. So we have angulation
and alveolar nerve. The angulation is looking at the direction that the tooth is sat. Majority of
wisdom teeth when it comes to extracting them they are impacted into something surrounding them so we
can look at the angulation and the positioning of the wisdom tooth and divide it into several forms.
We have horizontal, mesioangular, vertical distoangular and rarely you can have a transverse
wisdom tooth. By looking at this angulation, we can again potentially predict relative difficulty of
removing the tooth. Distoangular wisdom teeth tend to be slightly more difficult to remove
because the roots tend to be pushed up against the lower seven and so there's very little room
to either elevate or carry out surgical removal of bone. Additionally, in this portion we can look
at the nature of the impaction that the tooth is experiencing. Is it bone? Is it tooth? Or is it
soft tissue or a combination of these? Also under A is the alveolar nerve or to be more accurate
the inferior alveolar nerve. This is probably the most important part of the assessment that you're
going to do as this is the risk that most commonly will be relayed to the patient prior to removal of
a wisdom tooth. Additionally, it's probably the risk that has the greatest significance to the patient
because of potential implications if that nerve gets damaged. We can see where the nerve travels
based on the inferior alveolar canal which is seen as tramlines going through the mandible. When
these tram lines come near the wisdom tooth, there are certain features we look for that may indicate
that a wisdom tooth is a higher risk of damaging the nerve. These features include narrowing of the
canal or the roots of the tooth, radiolucency or darkening where the roots cross over the canal,
loss of courtication of the tram line so those tram lines vanish near the wisdom too or deviation
of the canal or the roots - are the roots hooked away is the canal suddenly jutting out of its
original course. If you identify any of these features it is fair to say to the patient that
they may be at increased risk of damage to the nerve. It then leads on to a further discussion of
potentially further imaging so this would include potential for a cone beam ct or even considering
other management options such as coronectomy if it's appropriate. And finally we have P so P again
I divide into two parts - pathology and peripherals. We have pathology - this is looking at any active
pathology surrounding the tooth so whether it is a cyst, whether it's periapical pathology
it is also looking at things like distal boneloss in patients who have recurrent pericoronitis
in a wisdom tooth they get some distal boneloss and this may make it easier to extract
the tooth. We then also have the peripherals so these are just other bits and bobs that you may
want to consider when it comes to evaluating the tooth. One of these aspects is looking at how much
bone is surrounding the wisdom tooth. If there's lots of bone surrounding the wisdom tooth for
example a tooth that is lower into the mandible then it's going to be more difficult to remove.
Along with this we want to look at the density of the bone the greater the density, the more
difficult the tooth will potentially be to remove and finally another thing that I like to look at
is the lower 7 that is adjacent to the wisdom tooth. I like to look at any restorations that are
there, is there a chance that this tooth may be damaged when we remove the wisdom tooth but also
potential restorability of this tooth because if this tooth looks like it's unrestorable and
should be extracted as well then it may well be beneficial to take this out first giving
you better access to the wisdom teeth. Now let's look at some example. So here we have a portion
of an OPT that demonstrates a lower left 8 in a patient. So let's work through the mnemonic
and assess this tooth. Firstly looking at the crown so there's no obvious caries that I can see
and the crown morphology looks relatively normal to me. Then looking at the roots so I can identify
two obvious roots - we have a distal root that looks relatively straight and a mesial root that has a
slight curve to it. Moving on to the angulation so looking at this tooth we can see is distoangular
and that mesial root is very closely pressed up against the seven this may add some complexity
when it comes to surgical removal. If you also look at the nature of the impaction
looking distally at this tooth there hasn't really been any boneloss and therefore it is
likely that the nature of impaction is bone and potentially soft tissue as well. Along with
this we look at the alveolar nerve so we can see the tram lines of the nerve traveling down
and where they cross the apices of this tooth, everything darkens off a little bit.
So remembering back to potential scenarios where the nerve is at higher risk of being damaged,
darkening of the roots would indicate this and so again this is a potential red flag that we
need to raise up to the patient. Finally looking at the P for pathology there
aren't any cysts, there isn't any peripheral pathology, nothing else there concerning me
and in terms of the bone that is surrounding the tooth, there's probably a normal level of
bone. The seven itself looks relatively healthy, there may be an argument of potentially some
distal caries there however a bitewing radiograph would be better at assessing this. So based on that
radiographic assessment I can tell the patient that the tooth may be slightly more difficult
to remove because of the fact that it's distoangular, there isn't any boneloss and speak to
them about their increased risk of potential nerve damage. So there we've looked at how to assess
a lower third molar effectively on a radiograph so hopefully you can inform your patients more
confidently of their risk. Please make sure to like, comment and subscribe and if you do have
any other suggestions of any videos please make sure to let me know. Until the next video, take care!