Thank you very much, Sophia, and thank you, Alison for great great introduction. I hope there's not gonna be too much overlap between the two, but I'm definitely gonna focus a lot more on the teeth and a lot less than the mechanics of the CT, . And, and how it actually works.
But, we're gonna start going back to basics a little bit and apologies in advance for the anatomy rehash, but we'll just have a little look at that and then run through some of the more common, common dental conditions that we see here. Particularly a infection is what we probably spend the majority of our time CT, it's various manifestations before we have a little look at some, supernumerary teeth and the various, weird and wonderful things that we see with odd temptation. We're gonna have a little look at, at, something that's very in vogue at the moment, just infant caries, and then we'll have a look at a couple of post extraction scans, which often presents some mixed excitement and terror.
And so just starting just a quick rehash of the of the the system that we use to number the teeth and and we tend to use this quite elegant system, the Trident system. Where each arcade has a number and then each individual tooth is assigned a number as well. So starting with the horses upper right, we call it the 100 arcade, the upper left is the 200, lower left 300, and so on.
When we're talking about deciduous or baby teeth, we change that the number of each arcade. So the upper right becomes the 500 arcade. So the first, or the central incisor incisor will be 501, and following on 67 and 800.
Horses tend to have reasonably standard dentition and the, the eruption times are, are, are published elsewhere, and they tend to vary a little bit amongst individuals, but generally are reasonably standard and a good way to to follow and given a reasonable estimate of a horse's age. If we just look at each of the teeth, types individually, we have a little look at the incisor anatomy. This is a nice longitudinal section of an incisor tooth.
You can see it's quite curved in shape. And because it has a nice, dense enamel coating and an outer shell that protects the the pulp on the inside. And when we look at the cross sections of each of the teeth, and we can see that the infant dibutum, which is another It is an enamel shaped, or sorry, it's an enamel lined cup, and that's pretty much just on the occlusal surface and and just a few millimetres below the occlusal surface.
So as the horse horse's tooth wears with time, the enamel cup wears out completely. And this has been used traditionally to age horses. But unfortunately, it is not recognised as being a reasonably inaccurate way of, of ageing horses because some horses will have very deep infinity, some will have very shallow.
So, the, the timing of at which it wears out can vary. Additionally, the the way that the horses use their teeth and can vary, how quickly it wears out. So crib biters, for example, tend to wear out their infant with their cup very quickly.
The other thing that we look at is the, the secondary dentin, which is the layer of dentin that protects the pulp from the outside world. And initially when when the tooth erupts, we just have this nice dense layer of primary dentin. And as the tooth wears down to this level, the pulp, the donla within the pulp will respond to the fact that the outside world is getting ever closer and it will then start to lay down a new layer of dentin or dense tissue to protect it.
And this appears as as the dental star on the cross section of the tooth here and again, as the horse ages, the the deadly star changes shape slightly according to the shape of the pulp chamber within the tooth. And again, this has been used traditionally to age horses, but again, some horses have got a very, very dense layer or thick layer of primary dentin this star takes a long time to appear. Os are born with a much more shallow layer of primary dentin.
So the the dental star actually appears quite quickly. Moving on from the insides we we'll have a quick look at the cheek teeth. So they've got 6 cheek teeth per arcade and we're referring here to the the 1st 3 pre-motors here and the 3 motors at the back.
And we tend to refer to those collectively as the cheek teeth, and we have 6 per arcade, so a total of 12 maxillary cheek teeth and 12 mandibular cheek teeth. And the 1st 2 cheek teeth, 6 and 7 on the maxillary arcade. They their appis or their roots live within the maxillary bone.
They're not associated with the sinuses at all. And, and the more caudal for usually, are usually associated with the paranasal sinuses. The mandibular cheek teeth are all lodged within the mandibular bone itself.
And the, the general rules that have been kind of touted in the past are that the, the maxillary eights and nines, so the last pre-motor and the first molar, have their agencies associated with the rostrum maxillary sinus just here and, and here, and, and that the maxillary tens and 11s are within the court of maxillary sinus. But not all horses really follow these rules, and the bony septum that we have just here in between the rostrum and called myxillary sinus actually has a variable position. Sometimes you will have the, the 10 living within the rostrums in the sinus or the mind within the caudal.
And in addition to that, the teeth tend to migrate more rostrally as the horse ages. So you can see there's obliqui teeth, the 10 and the 11. They're angled from caudal to rostrum and as they erupt, they tend to push for the rosterally.
And so the 10 actually if even if it starts out in the caul of my auxiliary sinus can end up in within the rostrum axillary sinus. And, on top of that, the roster limit of the rostrum ancillary sinus can sometimes vary in position as well. It isn't always nicely positioned right here at the junction between the 7 and the 8.
Sometimes it's a little bit farther rostrum, so you have a little bit of the 7 associated with the rostrum axillary sinus, or it can be a bit far of the caudal, and you can have either some of the 8 associated with the rostrum axillary sinus and some within the maxillary bone, or indeed the entire upper 8 can be within the maxillary bone. So this is important when it comes to identifying what teeth might be involved in in various manifestations of a infection, for example. So, CT has allowed us to sort of identify where these teeth are exactly within the head.
Looking at each of the individual cheek teeth themselves, on the, on the left here we have the maxillary cheek tooth and like the mandibular cheek tooth. As you can see them, the maxillary tooth is is much wider. It's a square.
And it has two additional structures, the infant these things just here, enamel cups filled with cementum and they have little dots in the centre, which are just little remnants of where the, the blood supply used to run when this tooth was developing. The mandibular tooth, on the other hand, is much more narrow and it's more rectangular in shape and doesn't have any infant dibula. So looking at the individual materials making up the teeth, we've got cementum that surrounds the outside of the teeth, that each of these teeth.
Then we've got a layer of enamel. We've got just one very intricate layer of enamel in the in the mandibular tooth, and this provides a very nice grinding surface. It's the hardest, densest material within the tooth and therefore wears much more slowly than the cementum.
So it forms a bit of a ridge and this increases the the area for for grinding food as they're chewing. Next we see the the primary dentin. We saw this on the incisor as well, and this is lives within the outline of this enamel, and then we have the secondary dentin, which is covering the pulp pulp chambers beneath it.
So we call these black spots on the teeth, the pulp horns, and they are, it's a layer of of dentin which has taken up some pigment as it's been laid down, which makes it darker than the primary dine. Each, each of the anxillary teeth and the teeth got 5 pull horns, except for the 6, which have an extra 1 and the 11, which sometimes have an extra 1 or 2. I mentioned before the infant dibula, here they are just here within this, this, this maxillary tooth, and again, the infant dibuum is surrounded by a layer of enamel, and this layer of enamel, this is the infantdibular enamel, and also wears slowly and just increases the surface area for providing food materials, particularly on the axillary tooth.
Just a longitudinal section just to to press home about this infantantibuum and the maxillary and infantdibuum, it's it's this layer of enamel just here. It's it's blind ending. It doesn't run all the way up to the axis, which are just here and in between the pulp chambers.
It is not sensitive. There's no blood supply and nerve associated with this. And it should be entirely filled with cementum as we can see on this tooth just here.
Here we can see the layer of secondary dentin, which is protecting the pulp just here from the outside world and preventing any bacteria from extending into the tooth. When we look at CTs, these various different materials and dental tissues become quite important because since the advent of CT we can now actually identify the individual materials on like on on more traditional radiographs. Looking at the density and and Alison talked this quite nicely, but looking at the density of the different tissues, we can quite nicely see that enamel, has got the most dense.
And highest hands feel unit, it's it's clearly discernible from cortical bone and certainly discernible from the other dental tissues which have got much, much lower hands feeling units. But most importantly and probably what we use most clinically is that the pulp itself has got quite a, a low handsfield unit or density. At -700, which luckily is reasonably higher than air.
And again, we use this clinically when it comes to assessing the pulp. You can see it just here. Our pulp is is a nice shade of grape, and then we can see these black specks within it, and that is signifying gas within the pulp.
So being able to discern those two things and take actual measurements is, is very, very helpful clinically. We'll move on to apical in infection, the most common reason for performing CT really in, in, in our population, and, and we'll just have a little look firstly at the causes of apical infection. Probably the most common cause of apical infection in horses, cheating and in particular, the maxillary cheek teeth is a process of acresis, which is just a fancy term for a bloodborne infection.
And the, the most common scenarios where probably a horse has an upper respiratory tract infection, and we as secondary to that, they get a bacteremia and you get bacteria getting into the blood supply. And the maxillary cheek teeth and sin and sinus blood supplies anastomos quite a bit. So you can get some of that bacteria settling out into the blood supply to the tooth and causing an infection.
And those teeth generally there won't be any initially anywhere there won't be any changes on the clinical crown. So you just have whatever signs you have associated with the the appis. .
Following on from that fractures of the tooth, if we get a fracture involving the the pulp horn and and opening up the pulp chamber we can allow bacteria in and get a sending infection. And horses are recognised as having certain patterns of idiopathic fractures, and the most one of the more common ones we see is idiopathic slab fracture runs just across here through the 1st and 2nd pull horns. But very often these are quite shallow fragments and only about 25% of cases of buckle slab fracture, do we actually see an infection developing associated with that, or it seems quite good at sort of sealing off its pulps when that happens and it's just a shallow slab.
Whereas a sagittal fracture or midline fracture where particularly maxillary cheek teeth where it runs through the infindibuly and then Typically that fracture will extend the entire length of the tooth that will come up here through the infantigulum and 100% of cases that have sagittal fractures will end up with an infection. We also see a infection as a result of advanced periodontal disease. So the, the disease starts out within the periodontic tissues within the mouth and and ascends to cause anapchial infection.
Probably the most common reason for such periodontal disease is diostomata, and we tend to see those more commonly in the mandibular cheek teeth. And finally, pulp horn exposure, poker exposure, anything that is going to open up the pulps and can allow an ascending infection. And one of the reasons that we sometimes see that is potentially for over rasping, and over drilling of teeth, and we end up with an infection as a result of that.
The regardless of the cause, the pathophysiology is pretty much the same. When you get infection within within the tooth, you get a pulpitis. So our our pulp up here, becomes swollen with edoema and and inflammation and as it does so, the blood supply coming in here through the apical foramen and as as the pulp, the soft tissues expand, the blood supply can become occluded at this point within the apical foramen and subsequently get necrosis of the pulp.
And when you get necrosis of the pulp, you end up with a tooth that ends up like this. Eventually you can see each of these pulp horns and contains food material because the tooth is is dead and has been dead a long time. All the secondary dentin is worn away and we have a hollow pulp chambers, and which ultimately end up filling with food.
Younger horses have got a a much better chance to overcome this apical infection, this, this pulvitis, and because this apical foramen is very wide when they're quite young. And so as the pulp expands, it's got it's got more room to expand and you may not end up with vascular occlusion and subsequent necrosis. Whereas older horses, and as, as time goes by, they, they lay down cementum around this apical foramen, so the frameen becomes narrower and therefore, even mild pulpitis can ultimately result in necrosis.
And just a little couple of of diagrams showing us and the various roots of infection, which, which varies slightly between mandibular and maxillary cheek teeth. And so as I mentioned before that we, we have got this infant dibuum which presents more opportunities. For for fracture, a midline fracture and and a infection, but probably, as I mentioned before, bloodborne or lymphatic spread and know as pancreas is most common for root infection.
So various different manifestations of a infection are seen and and and very much depends on which tooth and where it is. So the more common ones with the, with the rostrum axillary teeth, the sixes and sevens, we tend to see a facial swelling and this is left long to progress to a, a draining cutaneous tract as we see down here, and the pus just emanating from over the axis of that tooth where we've had an abscess actually rupture through the skin. Occasionally that can be associated with an 8 if again if that 8 is positioned a little bit more rostering and not actually within the sinuses.
And some cases we get both a facial swelling and the nasal discharge. So we see this sometimes with the sevens and the eights depending on their position relative to the rostrom axillary sinus. And, and we can also see it associated with concabulla and and Alison's already touched on the the the nasal concabully and we'll have a little look at those again in a few minutes.
And the more common one I guess that we see is unilateral nasal discharge, where a horse has got sinusitis, a secondary to an a infection associated with a tooth that is one truly within the sinuses. And then the mandibular cheek teeth are a bit more straightforward because they're always within the bone. We tend to start out with a big bony swelling, and usually a sort of a bulging in the ventral contour of the the mandible, and eventually this will progress to producing a draining sinus.
And traditionally we've always used radiographs, and, and once the disease has been around long enough, we can see some quite dramatic changes on this maxillary arcade just here. We can see this line has got clerosis around the appis and increased density of the bone. We can just about make out a little bit of clubbing of the roots as well.
This one down here again, we've got some decent clubbing of of this upper 9 as well. And both those radiographs are pretty convincing of advanced a infection, both of those teeth. The mandible your teeth also help us out quite a bit when when there's a draining tract, we can use a metallic probe to to follow the tract and if it leads us right down to the tooth, then it's again, fairly convincing.
The, the changes that we rely on radiographs tend to need to be fairly advanced before we can actually see them and and we we're looking at for root modelling and periodical bone changes as you can see here. We've got quite a bit of thickening of the cortical bone. And we've also got a bit of widening of the space, the perinontal space just here.
And we also look out for other things such as changes in the laminadu denta, which is this very fine line just here, which is a very dense bone lining the alveolus. But we've recognised that that radiography is not, not as sensitive as we might like for picking up on these changes. But conventional radiography, we, we see a sensitivity of, somewhere between 15, 69%.
With the advent of digital radiography, this has increased quite a bit and it can be as good as 80% in some cases. But the limitations are there, and this is as a result of the very, very complex nature of the, the equine head. As you can see from this scanogram just here, which is a just one of the images, the first image that we acquire before we do the CT sometimes.
It shows you just how complex the sinuses are, relative to the upper teeth in particular, and obviously you get a lot of overlap with with the teeth overlying each other. And the real problem it comes down to the fact that the that the changes that we're relying on are actually associated with the alveolar bone, which you can see just here in this maxillary tooth, and it's extremely thin, and it's it's with the teeth that are within the sinuses. There's a lot of overlying, tissues and various layers of tissue, but it, it takes a long time for this very important alveolar bone to show sufficient change that we can actually see on our radiographs.
So very often these cases are quite advanced by the time we can identify them on radiography. So moving on to our CT cases then I'm starting out with, with the first manifestation of apical infection, a facial swelling. This is a really nice case, this is a, a, a nice view, frontal view of a horse and apical infection, it's 107.
And on this, this slice just here, you can see this gas attenuation within the pulp chamber just here and on, on this pulp chamber as well. The infantivity we can just see in the centre just here, you can see the, the enamel. But you can see quite clearly that this gas attenuation is within the chambers.
More dramatically than that, we've got massive expansion of the periaical space with soft tissue attenuation. And then even more dramatic than that, the cortical bone, the axillary bone just here is extremely thickened and there's a, there's a great big defect in it as well. This horse hadn't quite progressed to the point of having a discharging cutaneous tract, but it certainly wasn't far off it.
When we do the 3D reconstruction just here, we can see that we've got quite a lot of of bony bony destruction. And, and that that was a a very nice case, a very nice clear advanced case, which probably we would have been able to identify pretty well on radiography, but the, the changes in the cortical bone, I think we can only be appreciated on the CTs we have here. And this tooth was quite advanced and and and most certainly needed to be extracted.
And in time that facial swelling and bony changes would resolve. Next one is the next manifestation that we will look at is horses that present with nasal discharge or sinusitis. And again, we've got a nice slice just here going right through the tooth and showing this gas attenuation, within the pulp chamber here and just tiny little bit just in here as well.
And we can see a little bit of change in the periaical space, but, but not all that dramatic. This tooth spot just down here has got a, a buckle slab fracture which is involved this pulp horn, and probably the 1st and 2nd pulp horns were open. Which allowed this as any infection to to move up through the tooth, and, and we have an active infection here.
Secondarily to that, then, we have got a sinusitis associated with this, and we've got this soft tissue attenuation, within the, sorry, delay of my arrows. We've got the soft tissue attenuation within this rostrum axillary sinus, and you can see that there are little small densities, . Gas densities within that soft tissue attenuation.
So that that pattern on the CT would suggest that this horse probably has got insus in its, within that sinus. When we look at a sagittal slice of the same horse, we we see it again, we've got our sinus that's we've got our gas attenuation and our chamber here, and we have got our bony septum separating our rostrum axillary sinus, which is just here from our recording axillary sinus just here. And you can see that this is actually 110.
This horse isn't all that old, but the 10 has actually migrated quite a bit rotally, and this bony septum separating the caudal and roster axillary sinuses, it's just sitting right over the tooth. So this, the positioning of this 10 has meant that this horse has got sinusitis within the rostral sinuses, which actually saved the coral sinuses, and there's no evidence of sinus sinusitis back there at all. And again, these are your little gas pockets within the soft tissue attenuation which can suggest to me that this pus is inspiated and quite cottage cheese like and therefore it's very, very unlikely to ever make its own meat out of the sinuses and and this course would require sinus surgery to remove that that material as well as extracting the tooth.
And this is another case of a horse with an a infection of its 7 that the slicing just here doesn't actually show that the changes in the tooth, I'm afraid. But this is going back to the ventralcoca bullet, which Alison had touched on very nicely earlier on. This is the the bullet just here, which is filled completely with uniform, soft tissue attenuation unlike the opposite side where it's nice and a gas filled.
And there's destruction of the periacal bone just here and the maxillary bone. This was did actually also have a draining tract associated with this maxillary 7 infection. So as, as well as that, as a result of that infection.
This horse got emema of this ventral coal bulla, and it appears as though the the the soft tissue attenuation is actually spilling out of the bulla, and this bull has probably actually ruptured and is discharging the pus from within it. So this horse presented with a facial swelling, a discharging cutaneous tract, and a nasal discharge. Even though it didn't have any sinusitis because it was 7 unrelated to the rostrum axillary sinus, and there was no sinusitis, but there was a ventralcoccal bulla empama and causing a combination of of clinical signs.
A little bit of repetition here at following Alison's very nice presentation, but just looking at these comical bully and at various different stages of the horse's age, they've got 4, they've got 2 dorsal and 2 ventral and in this mature horse just here, you can see that the bull are quite nicely open and well formed. But you can see just how close these maxillary sevens are, to the actual build themselves. And when we look at an immature 2 year old, you can see the developing and mature or permanent sevens just here with the deciduous 7 just overlying them still haven't quite shared.
Won't do so for another year and a half or so, but you can see these tiny little ventococa will have been completely, squashed by these developing teeth, barely have any cavity at all, whereas the dorsococcal bus a little bit larger. If we look at a a a a cadaver specimen of, just to have a closer look at these, at these conical bully, we've got a longitudinal section of a horse's head on the top, and it's been sliced just at a. To the the nasal septum, and we can see here we've got the dorsal coal scroll just here, which forms the dorsalcoy sinus at this level, which you can see just here when we take the medial wall off the scroll and then just draws from that we've got the dorsal con bulla, here's our scrolls.
There's the dorsalcocabull and you can see quite clearly there is an intact septum just here between the dorsalcocal sinus and the dorsalcocabua. They don't, ever communicate in in naturally, but in disease, if you, if you've got sinusitis or bullet and ya, you can get fistulation between the two. And ventrococcal bus is the same scenario, and occasionally you can get an emma of either these structures associated with with sinusitis, but also associated with those seven apical infections and manifest as as a nasal discharge eventually.
He's a little montage of some dorsal cockabula eminemia at the top and some pecockcabull emine at the bottom. You can see again, we've got some in most of these, so this one here in particular, we've got that mixed attenuations we've got soft tissue attenuation with little little pockets of gas within which again suggests that this is inspiated pus and I think that's what we see most commonly with these empyema cases that that pus has been sitting around for a very long time and becomes desiccated and is very much instigated by the time we actually get to it or see it. And some horses do us a favour and and the disease progresses to a point where the the bullet actually ruptures, as we can see in this case just here.
And, and by that stage, we've got a usually a foetid and foul smelling nasal discharge, which could easily be misinterpreted as a sinusitis, without performing synoscopy or CT or radiography, . And the the specrococcal bully at the bottom, and again, to get, get, endoscopic access to these, you very much have to take your scope up the middle meatus just here, work your way in between the dorsal and ventralcocal scrolls and can meander up and down to try and find where the point of drainage is or indeed to create drainage surgically. These can be accessed endoscopically.
Using various, instruments, very often homemade, to access these bully to to create drainage. And The apart from the more dramatic presentations of of a infection, we do often stumble upon these incidentally, and we catch these cases of of a infection before they actually show any signs at all. This is a horse that was it was a head shaker in fact and was having a scan and the head shaking was attributed to THO or temporal hyoid osteoarthropathy, but we incidentally found just this tiny bubble of gas just here in the in the pulp chamber and the early changes within the rostrum axillary sinus here, we're starting to see the onset of sinus lining inflammation with this, these focal increases in soft tissue attenuation within the sinus.
So this this case can be tackled quite early on before, before the a infection has a chance to to progress and and cause andvert sinusitis, and this tooth can either be extracted or or endoontic therapy could be performed here just to try and save the tooth. Certainly, endodontics are coming on leaps and bounds at the moment. But if we get to the point where there is puss associated with with the tooth either within the sinuses or because of a sinus strain tract in the skin, then, typically those teeth are beyond saving with endoptic therapy.
But picking up at this stage, you certainly have got a reasonable chance of saving this tooth. Another case very, very early, apical infection again we've got this, expansion of the perapical space just here the the there is some soft tissue tenuation in the peri apical space and within the alveolus and and we've also got a tiny gas bubble within that within the apus within that apex just there within the soft tissues. And again, this tooth and it's it's a 10.
It hasn't progressed to the point of any evidence of sinusitis at all here, so this tooth was caught very early on, and again allowed us to, to do something about it before it progressed any further to sinusitis. From the very early to the extremely chronic, teeth that are left infected teeth that are in place for a long time, can result in sementoma formation. So you can see just here these very dense mineralizations, around the aps of of of this.
This is all this the only slices are from the same force, . This horse has done quite a good job at walling off this a infection. You can see just here, this pulp chamber within the tooth is actually completely full of soft tissue attenuation, which turned out to be food material, and this this tooth was dead for such a long time that the the pulp chamber was open and it filled completely with food.
And this was quite a young horse and had developed an infection, presumably some years previously when the tooth was very young and had a big wide open apical foramen. And therefore the tooth is able to mount a response to try more off this infection, which it did very successfully in many ways. You can see that there was this massive expansion within the sinus, but it wasn't actually any overt sinusitis.
In addition to all this new bone formation, we have this sematoma in the centre which is Just a dense accumulation of of cementum that is sitting within those within that reactive tissue. This case actually presented because of quitting. It had all pain because all the food that was actually accumulating up inside here was causing this fragment of the tooth to be slightly displaced and was causing some block ulceration just here.
So we ended up having to remove that tooth and, and all this periaical tissue and eventually removed that sementoma. We needed to do a transvocal approach in order to reach that sementoma. But again, this horse got away without having any sinusitis because of the horse's inherit ability to to sometimes ward off these infections and when the tooth is is quite young, that wide apical foramen, and can mount a bit of a response to, to the disease.
Here's another case of quite dramatic semenoma accumulation and the lie to you we notice that this horse got a very asymmetrical face here and this was due to a kick in when it was just 3 days old. But latterly it presented to us with with a fractured tooth, and it's a sagittal fracture and again it had. It probably occurred quite early on and that had managed to wall off this infection and lay down some sementomas.
And we use the CT in these cases was really, really very helpful in determining just how deep that the semen tomas were and and to devise an approach in order to remove those very large structures. Moving on to supernumerary teeth, we, we encounter those reasonable regularity, and they can cause horses quite a lot of problems. They can be quite a welfare issue, and it's quite easy for them to go on, particularly in this case just here.
This is a supernumerary 12, and at the very, very caudal aspect of the mandibular arcade with this tooth had gone on on. Growing unchecked for very, very many years. The point was it overgrown and this horse had quite a lot of ulceration on on the the palate, and as a result of the very, very sharp overgrowth that had developed.
In addition to that, some of these, Supernumerary teeth will oppose the other normal cheek teeth in various weird and wonderful ways and can form diastoma, which allows food to to become trapped in pocket and cause very severe periodontal diseases we had this this particular case here, sorry, we had an accumulation of food just within the between those two teeth and, and, some developing periodontal disease. CT is really helpful in determining the position and and the structure and the morphology of these teeth. Here here's a nice image of a of a horse with a supernumerary on its maxillary arcade and and when these teeth, the supernumerary teeth are more.
Logically normal, and we refer to them more correctly as supplemental supernumerary teeth. And as you can see here, this tooth does look very, very similar to the more normal tooth. And we can, we can assign this the number 12 when it's a supplemental and normally morphological tooth.
When they present, they can often present with large overgrowths, as you can see, these two are displacing each other, and this horse had had some rasping performed before it came into us because of a very large, lingual also that this particular displacement was causing. So using the CT and here we have a multi-planar reconstruction of the same horse. We can see that there's a various combination of actually three teeth just kind of jostling from the same space, in this horse's mouth.
And, and using these, these various imaging, techniques, we were able to sort of make a plan with the clients and, and, and offer extraction because we could see exactly where the tooth was running, or also offer the option of of leaving them where they were, and just managing the, the associated overgrowth. Sometimes these supernumerary teeth are not morphologically normal. They're they're a little bit more dysplastic, and this is a nice intraoral image of a horse that presented again with very, very chronic lingual damage and, and this odd dental structure just emanating out of the the the beside the normal arcade.
On the CT, you can see that it is actually, it's certainly a dental structure. It's it's, it's got one pulp chamber in it, so it's a vital structure and it's sitting adjacent to this this more normal mandibular tooth. When we do take some more slicing, to have a little look at whether or not we could extract this.
You can see this is a very, very narrow, very So be looking tooth, which actually wraps itself entirely around this age just here. The the tooth actually it starts out on the the lateral aspect within the within the mandible and then curves in between the 7 and the 8 and then courses more proximate to exit or to erupt on the lingual aspect of the age. So if that was elected to be left in place for that extraction that was going to be extremely difficult without damaging the other teeth and the owners were offered the option of removing it, but again elected to manage that over every 6 months or so and, and leave the structure in place.
And I think had we had just looked at that, that intraoral image and thought we could just extract it, we could have met with quite a nasty surprise. And dysplastic teeth, and other various manifestations of other supernumer teeth are really nice, nicely imaged or visualised when we perform these, these 3D reconstructions and they give us a really nice view of exactly what they're doing and where they're running and and certainly for teeth that we're planning to extract, knowing exactly what they're up to before we make an attempt is often very, very useful. This teeth just here was a very dysplastic.
In the place of where the normal 9 should be. It was comprised primarily of cementum and as a result, it was wearing away much more quickly than the adjacent teeth. And so this horse was getting an associated overgrowth on on on the opposing tooth.
Again, we didn't need to do anything about that tooth. It was useful to image it and to know what was going on, but extraction wasn't necessary in that particular case. Again, it was just a case of managing this overgrowth in that tooth every 6 months or so.
This one on the other hand, this horse had already had an extraction of the 7 just here and and this 8 started to play up. This horse was having a clinical signs associated with it. And how we attempted to extract this sort of quaver or curved type tooth, I think we would have again come come proper and if had we attempted an oral extraction as you can see quite a portion of this tooth is running almost horizontally, and an allo wall section was required to actually extract that tooth in its entirety.
And moving on to, the next condition, which, which is infindibular cemental hyperplasia and, and the condition that follows on from that, which is infandibular caries. This is a little Welsh pony that presented . For an infection, in fact, as you can see, it's got some funny displacements of rotations of its eights just here, but more, more striking and more dramatically, it's got huge gas attenuation, within the, these lines just here and and within its sixes, it's.
And the nines, and that that is the the infant di, which is almost patent. There's we have the enamel cup, which you can see just here, certainly in place, but the cementum, which should be nicely filling this is almost completely absent in this case, at this level, these patent infindibily once the tooth is worn to the point of this patency, we end up with food sitting in there and that food will sit there. The, the Edinburgh Group published a really nice survey, at the beginning of last year where they looked at, the incidence of infantdibular caries and decay within the infantdibuum this year, and came out that 49% of.
Have a degree of care is associated with. She teeth, and these horses have some of this infant mental health. Why exactly they.
Like the cementum is plastic is still pretty poorly understood, but something to do with occlusion of the that's supplying the developing tooth which cut short this process by which this infanttibuum fills with cementum, most commonly affected teeth ns followed by the eights. Tends, and the, the degree to which the infantimum is, is taken varies massively with the larger the. OK this will develop And this is a nice grading system which has been devised.
Sorry, Justine, just to just you, your microphone, your microphone moved because you've just, you sound a little bit distant. Sorry, is that any better? It was a little bit better a minute ago.
How's that? Oh, that's much better, yeah, thank you. Sorry, apologies.
And just a heads up, you've got 15 minutes to go as well. OK, thank you. This is a grading system that we, that has been adopted for looking at infandibular caries, and we can see this first maillary cheek tooth just here.
We've got just a little tiny dots that remain from where the blood supply used to run, and those are not considered significant. Grade one, we've got some early decay of just the cementum within the fundibutum. Grade 2, it affects the enamel and the the cementum.
Grade 3, the decay has been to progress out into the dentin and at both the primary and also in this case into the secondary dentin. This is an advanced grade 3 where there's so much decay that the two indibium have coalesced to form a large cavity, and these are the cases that can progress to a grade 4 where you've got these sagittal fractures. And you can see the two fragments of tooth you can split apart and there's food filling in the defect.
Again, this is just another nice slice of showing these, these cases, with the infant dibuli which have got no cementum in them, we've got just gas, and, and these infantility tend to get, get much larger to the apical aspect. So we tend to see these, these cavities much larger as the horse gets older. You can imagine when the tooth the the surfaces at this level just here, these will be extremely large cavities.
This, this case just here back to our, our host the face, this is just a nice, illustration of, of what these, sagittal fractures look like here we have a clinical case and a photograph of the probe showing the, the, The split in the tooth. So the path of physiology, we've got this mental hyperplasia, we get food sitting in this cavity which causes decay and the carries. We then get this sagittal fracture occurring, inevitably we get a infection and typically as a result of that, then we get sinusitis.
The infantdibuum, as I say, it's got, it's got very hidden depths. You might, you might see these little defects, on your clusal, exam or or your oral exam, you see them on the occlusal surface. You can see here at this level, we've got gas, but at this level we've got food filling this rostral inindibuum in the 8, but it, it certainly doesn't.
Give us any idea of how deep these infant tibie actually are, and you can see just this cross section. The in runs the majority of the length of the tooth, and knowing how far the decay actually runs is very difficult to discern just on an on the oral exam. So more recently we've started to to to do something about this these carry cases and to try and prevent the progression to sagittal fracture.
You can see here this . This infant dibuum had the food material has been picked out. This has just we start the drilling process with removing drilling out all the necrotic material, and then we place composite resin fillings within the, within the actual cavity for two reasons.
One, to stop the food from filling any further, preventing the disease to progress from progressing, and it also improves the structural integrity of the tooth and hopefully limits the risk of fracture. Here's a case that has had some restorations performed, and you can see the very, very dense, filling materials within the infant dibuly . The, the putting fillings in the more cordial teeth as they are just here, a 9 and a 10, it involves a little bit of, of, imagination as you're doing it, the visualisation isn't, isn't fantastic, and it is inevitable that, a lot of these feelings will not completely filling fundibuum, particularly the more apical aspect.
And for that reason, whenever we perform this, we always advise our owners that it will reduce the risk of fracture, but unfortunately we won't completely remove the risk of fracture. Just moving on to some post extraction scans, sometimes they come back because there's problems, sometimes they come back because, we want to just make sure everything is OK. And here we, we see, a horse that's had an upper seven removed, and this is, this, shows that the, the, alveoles is filling with nice uniformly, soft tissue attenuating material, just granulation tissue filling the alveolus, a little bit of food materials sitting in here, but you can see the alveolus is almost completely filled.
The surrounding bone, the alveolar bone looks pretty smooth. This thickening of the, the, the magzilla, was as a result of the disease and this is beginning to settle down and should fully resolve in the following 6 months to a year. This is a case, which came back, which came into us for for CT having had a mandibular tooth repulsed, and it had a very large swelling in its mandible, and also had poor granulation filling the the alveolar so it was failing to heal.
And this horse, as you can see here, has got a lovely developing sequetrum. With a big periosteum reaction on the natural aspect of this mandibles, this, this, this man is trying to eject this piece of dead bone. You can see it just here.
And there's, there's going to be inevitably this alveolus won't heal, until that sequester has been removed. So this, the scan was was very helpful in determining a means by which to access that sequetrum, and, and to curate this mandible and finally get resolution and healing. This is another nice case.
This was a horse again that came into us, for CT scanning. It had, a maxillary 9 extracted and had sinusitis, sorry, maxillary age extracted and sinusitis treated, and the alveolus is healing quite nicely as you can see here, and the sinusitis, according to radiographs appeared to have resolved, but an ongoing nasal discharge. When you look at this, at the, the, this section just here looking at this ventralcocal bulla, which has completely lost its roof just here, so it's perforated.
And just sitting inside the bulla, we've got this dense area of mineralization. So there was a calcified body sitting within the bullet and that was driving. That ongoing nasal discharge from this bullet and ya, and this, this force had, when we took several more scans, we could identify exactly where that, mineralized body was and eventually had to perform a rhinotomy actually to access it in order to remove that that necrotic body or mineralized body and to to curate out this .
This bulla, in order to get resolution of the of the nasal discharge. Just incidentally, this tooth, this horse also has got a dysplastic tooth on the opposite side, which, as you can see, this is quite an old horse, and this tooth never caused any problems in sinusitis on that side. Just a couple of last just a couple of cases just to finish off.
This is our largest case today to go through the new CT, and you can see our, our head nurse Jane here whispering some sweet nothings in her ear. This was a 960 kg shower that we put through the CT, for a, a facial swelling. And when we performed a scan, we found that she had a sinus myxoma, which was causing complete destruction, of the apuses of this maxillary tin and that we allowed us to sort of plan our our sinus surgery and also to to to plan the extraction, which was inevitably going to result in a in a fistula as well.
From little from large to little, and this is the, the same, goat that, Alison showed us in, in our previous scan. This is our, our little friend going through the CT scan. And this is just to show that we don't just do horses, but we do some, but they do, but ruins all have very similar dentition in some ways to to horses.
This little goat had, it's a diastoma here between its maxillary cheek teeth, which had caused a lot of food to pocket just here and eventually formed a fistula, . So it had massive big bony swelling and bony destruction in here and a great big abscess actually within the size where we had been walling off the food material, which had been pushed up into the sinus fistula. Here we see a couple of other slices to show exactly just the level of destruction and disease within these sinuses.
So this little thing, eventually went to surgery, very similar to a horse or extraction we extract the tooth in the same way, but also had to perform a sinus surgery and and this is our little, sort of mocked up or or our Heath Robinson version of of a sinus lavage for a goat and and following on from that, this little thing had a complete resolution as well. So that's just a quick run through of how we use CT in our, in our, in our dental cases and they say it's gonna make dentistry much easier but certainly does make the decision making an awful lot easier for me anyway, and I'd like to thank everyone for listening and invite any questions. Oh that's great.
Thank you very much, Justine. Really nice refresher of Keith anatomy as well, for everyone at the beginning. So it really does look as, I think it's kind of echoing what Debbie said that actually CT images, are you preferentially really using them over a geography now for, for the, for these teeth cases?
Yes, I, I am almost exclusively, to be honest. It's so quick and it just gives so much more information. The this the the only time I really end up using radiography at the moment is during difficult extractions, .
Doing trans buckle extractions or you just need to guide the surgical technique for diagnosis, the CT is just, it makes life so much easier and just gives us so much more information. The number of cases I, I can think of that, we find additional pathology, you know, I go in to take one tooth out because of that, and obviously it become infection. More recently, I had a horse that came in with facial swelling.
And an infected 7, we found 3 other teeth that were also infected on the scan and allowed us to tailor our approach to that case and to to sort of stage extractions, but also to do it promptly enough that it didn't develop, the horse didn't develop additional clinical signs and get those sorted before we we had disease elsewhere. Yeah, and just regarding quickly, the, when you're taking the CTs probably refers a bit more to Alison's talk, but do you get any movement blur because you, you leave the horse alone whilst it's taking the images. I know it's very quick, but does that, is that a big problem or not, or not really is the To be honest, we do have to repeat them occasionally.
It's, it's with our current setup, it's great because nobody has to be in the room. So previously if we had to repeat, we also have to take into account the fact that we were exposing ourselves and everybody else and a horse having a couple of doses, it shouldn't be too much of an issue. We occasionally we get a little bit of blur.
And if it's in an area that's that's important, then we will absolutely repeat it. It only takes a few seconds. And the timing is really important and I think we kind of get to know our cases reasonably well.
Cobs have a really, really fun habit of just sitting backwards. We can account for that. We wait for them to sit backwards and we position and then when they're sitting backwards.
Little ponies sometimes, if they're a little bit too short, especially for our stances sometimes we be in there with them and sort of encouraging them to move forward and we can kind of control that a little bit more and we can kind of give the thumbs up to the technicians and when to press go. But by and large, we can get away with it such a quick scan and that we don't get much movement at all. And then I guess because you're not taking, you know, so many radiographs and having to repeat radiographs if the angle's not quite right.
Are you finding the costs pretty similar by the time you've you've done all that or not, not really? Lower? You know, just, just we don't, we don't charge for repeat CTs for the same study.
So overall, I, with our current setup, we probably the imaging is is is cheaper just running constant repeats. Yeah, so CT scanning for dental definitely seems to be the makes my life a lot easier. Yeah, brilliant.
Well, that's, yeah, a really, really good talk. Thank you very much again.