OK, so this first lecture is going to be on malocclusion. So the learning objectives for this lecture are to be able to end up recognising a normal occlusion. To be able to classify different types of maoclusion that we commonly see in cats and dogs, to understand the consequences of maleclusion for the patient and to understand the different treatment options available for traumatic malosions.
So Andy has covered a separate lecture which talks about oral and dental anatomy, but just to recap for the purposes of this lecture. We need to understand some important terms as they relate to the oral cavity, because, this is how we're going to describe exactly what the maoclusion is that we're seeing. So these are terms that reference to surfaces in relation to one another.
The first terms that we have are buckle, labial, and facial, and they essentially all mean the same thing. And that pertains to the tooth surface that is facing the lips in both the maxilla and the mandible. So I would commonly refer to that as the buckle tooth surface.
Then opposite to that, on the other side of the tooth, we have what we call the palatal or the lingual tooth surface. So it's palatal when we're talking about teeth that are in the maxilla, and it's lingual when we're talking about teeth in the mandible. And then we have the terms medial and distal, and these are terms that mean the opposite to each other.
The medial tooth surface is the surface of a tooth closest to the tooth in front of it. And the distal surface is exactly the opposite. So that's the surface of the tooth closest to the tooth behind.
And what I've done in this picture is to show which surfaces, What the what the labelled surfaces are for each of the teeth pictured, so the the labelled surfaces of the first incisor, the canine, and the maxillary force premolar. So in order to identify what's abnormal, we need to be able to identify what's normal. This is my poor long suffering spaniel.
He's always a good anatomical study and he had a relatively normal occlusion. So that's to say that his his jaws are an isognatic. And what that means is that the width between the left and the right maxilla is wider than the width between the left and the right mandibles.
So that's normal in both dogs and cats. They essentially have narrower lower jaws than they have, upper jaws. We have got A variety of different in insider occlusions that can be normal.
The canine occlusions, It is normally quite tight in dogs, and the mandibular canine tooth should sit in the little diastoma between the maxillary canine tooth and the maxillary third incisor. And when the mouth's completely closed, the mandibular canine tooth should sit just on the buckle aspect of the gingiva. In the maxillary jaw between those two teeth.
So that is a normal occlusion. The pre-molar and molar occlusion is is a sort of a scissor bite. Rotally in the premolar region, most dogs tend to have what we call an open bite, where when the mouth's completely closed, the premolar teeth don't contact or slide over one another.
There's a little gap between the maxillary premolars and the mandibular premolars. And then further back, towards the carnasseal teeth, which is our maxillary 4th premolar and our mandibular first molar. We have a scissor reclusion here where the maxillary 4th premolar slides over the buckle surface of the mandibular first molar tooth, and that's, That enables them to carry out their highly specialised functions of tearing and sharing food.
And then roughly the maxillary premolars match up with the mandibular premolars. Whenever we're assessing occlusion, it's really important that we make sure that at the front of the jaws, everything's correctly aligned. So, I make sure that the maxillary first incisors are level with the mandibular first incisors, because some types of maoclusion can actually cause the mandibles to deviate either to the left or the right through the incorrect interdigitation of the teeth.
So on the left, this is a normal incisor occlusion or one of the normal incisor occlusions. So this is a scissor bite. Where the maxillary incisors slide over the buckle aspects of the mandibular incisors.
And there is another type of bite that's also considered normal, which is a level bite, which is where the maxillary and mandibular incisors sit in exactly the same plane, and the maxillary incisors sit between the cusps of the mandibular incisors. Again, we can see in the picture on the right this very close or tight interdigitation of the maxillary third incisor canine and mandibular canine tooth. And when the mouth's closed, the mandibular canine tooth is just resting on the bus buckle aspect of the maxillary gingiva.
So that is a normal a traumatic occlusion. We have a similar situation in cats. They have a very similar occlusion.
They're an anisynatic, so they have wider maxillae than their mandibles. And we have A much tighter occlusion between the canine teeth and incisors in cats. And the clinical implication of this is that even minor trauma, such as that that might be sustained in a road traffic accident can have a significantly deleterious effect on inclusion in these patients.
We can see that they have a similar instigation of the pre-molar and molar region. And the maxillary premolar sits between the corresponding premolars in the mandible. And then, their big carnase teeth, the maxillary 4th premolar and mandibular first molar teeth slide over one another to enable, chewing and shearing functions during mastication.
And we can see that the cat in the left has a scissor bite of the incisor region, which is completely normal. So why does it matter if our patients have a maocclusion? Well, to point out the obvious, usually when teeth or jaws are incorrectly positioned, this tends to result in pain for the patient.
And that's usually because, it leads to abnormal contact between teeth and either the soft tissues such as the, the, the palatal oral mucosa, or, Incorrect seclusion of tooth on tooth. Ultimately, if if a tooth is inappropriately contacting the oral mucosa in the roof of the mouth, ongoing continuous worsening trauma can result in orinasal fistulas. As we've already discussed, some types of maleclusion can cause deviation of the mandibles relative to the maxilla, which can Result in abnormal forces in the region of the temporary mandibular joints, and this can result in degenerative temporomandibular joint disease.
We, we can also see pulpitis, so endodontic disease resulting from maleclusions, particularly where we have tooth on tooth contact. This is when you start looking for it, it's actually really common in brachycephalic patients that have a class 3 maleclusion, which we'll go on to talk about later. This is my spaniel again, Alfie.
And what you can see is that in his maxillary teeth, in the maxillary canines, he actually has some attrition, and this is really common in spaniels. And we think this possibly results from, hypermobility of the temporary mandibular mandibular joints, enabling more, more lateral movement of the mandibles relative to the maxilla. And we can see that we've got attrition of the medial aspect of the maxillary K90.
And finally, And particularly with reference to young puppies that have deciduous dentition, if they somehow the deciduous mandiular canine teeth are contacting an abnormal region of the roof of the mouth, this can create what we call a dental interlock, which is where the The deciduous mandibular canine teeth physically lock themselves in a region relative to the upper jaw, due to creation of indentations in soft tissues or interaction with other teeth. And this can prevent normal jaw growth either of the maxilla or the mandibles. Jaw growth is genetically predetermined.
It's something that's dictated by our genes. But the mandible and maxilla don't always grow at the same rate to one another. They often play catch up.
So, this can This can mean if we perform interceptive orthodontics, which is The extraction of deciduous mandibular canine teeth in order to relieve a maocclusion. This does also have the benefit of removing the dental interlock for puppies that have jaw length discrepancies to allow their jaws to fulfil their growth potential if their genes dictate it. So how can we accurately assess seclusion?
Really, this can be difficult in a consultation. Lots of puppies are really wriggly and it can be, it can be very challenging to be able to get a puppy to close its mouth and lift the lips and stay still for more than a couple of seconds. So we can ask owners to take photos at home if we can't, if our patients are being uncooperative in a consultation.
And what we need to ask them to do. Is to close the mouth and lift the lips away from the teeth so that we can see how the teeth. Interact with one another when the mouth is closed.
It's much easier to do this, comprehensively when the patient's sedated. So just before an anaesthetic, when we've given the patient a premedicant and they are slightly sedated, we can most accurately assess occlusion at this point. It's important to note that we can't assess occlusion with, when, when a patient's intubated.
So either we need to extubate them to properly assess occlusion, or we need to disconnect the endotracheal tube from the anaesthetic circuit and push the endotracheal tube further into the airways to enable the patients to be able to close their mouth properly to assess occlusion. When we're talking about maoclusion, we have a classification system so that we're all able to understand, what it is that we're describing when we're talking to colleagues. And what we've ended up using is a borrowed human classification system that works really well for our patients.
So there are 4 classes of maloclusions that are described by Angle many years ago. Path one is what we call a neutroclusion. So this is where the length of the maxilla relative to the mandibles is normal.
But what we have with the class one mao lesion is mal position of one or more individual teeth. And we can subdivide class one maoclusions into, exactly, we can describe exactly which tooth it is that is maocluded, and we can describe that tooth in the direction that it's, pointing abnormally, be that me averted. Linguverted or plate averted, dis diverted or buck averted.
Then we have a class 2 manocclusion. This is also known as mandibular bracognasism, but more scientifically correctly known as mandibular disocclusion. So a class 2 Maloclesion essentially describes mandibles that are shorter than the maxil.
And then we have the inverse, which is a class 3 maloclusion. Sadly, this is what we have. Breed to be normality in our brachycephalic patients.
A class 3 manoclusion is a mandibular pronatism or a mandibular mediacclusion. So essentially this is describes longer mandibles relative to the maxillae. So very common in brachycephalics, and sadly, it has become the breed standard in many brachycephalics.
And then the least common class of manoclusion that I see is the class 4 manoclusion. This can be described as a rye bite, and it describes a rostrochord or asymmetry of the maxilla or the mandibles. So let's have a look at some pictures.
These are all examples of class one maloclesions in their various forms, and. So therefore, these are malocclusions where we have a normal jaw length relationship, but mal positioning of one or more teeth. So for example, we can see in picture one, we have got an abnormal position of the right maxillary canine tooth, which has led to an abnormal position of the right mandibular canine tooth.
This is called a lance canine or a meioverted canine, and we see this fairly commonly referred to as And the abnormal position of that right maxillary canine has created an orthodontic force on the right mandibular canine to cause buckle tipping of that right mandibular canine. And the same thing is going on in picture 2 to a slightly lesser extent. In picture 3, we have what's called an anterior crossbite, where we do actually have an abnormal, a normal jaw length relationship, but we have an abnormal relationship of the, maxillary first and the both maxillary first incisors with both mandibular first incisors.
Their normal position has been reversed. And this is called an anterior crossbite. In picture 4, this is something that you'll see all the time, but you may not recognise this as being a maleclusion, but it is.
This is the situation that we're often in with smaller patients or brachycephalic patients where we have overcrowding of the pre-molar molar region. This is sometimes due to rotation of teeth, or, or skull shape and size. And as you can see in this image, what we've got is early onset periodontitis between the mandibular 4th premolar and the maxillary, the mandibular 4th premolar and the mandibular 1st molar teeth.
Because of the close contact and the trapping of plaque bacteria between those two teeth, it's resulted in early onset periodontitis. In image 5, we have what we call a posterior crossbite. So, picture 3 with an anterior crossbite, an inverse relationship of the incisor teeth.
In image 5, we have an inverse relationship between the maxillary 4th premolar and the mandibular first molar, and this is leading to a traumatic occlusion, where the maxillary 4th premolar is contacting. The lingual surface of the mandibular first molar inappropriately. Images 6 and 7 are things that you will all see all the time in general practise, and this is a puppy with a normal jaw length relationship that, linguverted deciduous mandibular canine teeth.
And this has resulted in traumatic indentation of the Maxillary or palatal mucosa. So in picture 7 you can see the indentations that that's causing when the muppy, that when the puppy has its mouth completely closed. And that's gonna be painful for that puppy.
So this is a class 2 maocclusion. Again, this is relatively common. This is where we have an abnormal jaw length relationship and the mandibles are shorter than the maxilla.
This leads to what we call a relative. Displacement of the mandibular canine teeth. So the mandibular canine teeth may be in a normal position in, in the mandibles, but because the mandibular jaw length is shorter, It results in abnormal contact of those mandibular canine teeth with either the maxillary canine teeth or the palatal oral mucosa, and this will really commonly result in an or a nasal fistula if it's left untreated.
It can also result in periodontal damage or attrition of the maxillary canine teeth as well. And then our poor brachycephalic patients who have been bred to have a class 3 maleclusion. And in most cases, these are actually sadly, not commonly recognised as a traumatic maleclusion.
So these are patients that have longer mandibles relative to their maxilla. And as a result, usually the traumatic occlusion is rostral in the incisor and canine region. And sometimes we see abnormal contact between the canines and the incisors, and this would be uncomfortable for patients.
It would result in concussion injury of the teeth. And as we can see in the picture on the bottom right, the right mandibular canine has actually orthodontically moved the right maxillary third incisor. In the picture above that, we can see, something that occurs very frequently, and that is we've got a traumatic contact of the all of the axillary incisor teeth on the lingual aspect of the mandibular incisors.
And this isn't good for the health of the teeth because what we get is a repetitive concussion injury of maxillary incisors, and it's really common to take radiographs of these patients and find that the maxillary incisors are non-vital because of the The, the chronic concussion injury. And what we can see on radiographs is cessation of narrowing of the pulp cavities or apical periodontitis, which can appear on radiographs as apical lucencies. And then these are our very weird class 4 allocclusions, which I see perhaps once or twice a year.
And this is asymmetry of the left and right jaws. Usually, this results from trauma. And most often this is trauma to young puppies that are growing.
And we can end up with all sorts of weird and wonderful presentations in these patients. Most often, they'll need a CT scan for full assessment of their maocclusion. Let us not forget our feline patients.
Mao lesions do occur really commonly in felines. They can have the same classes of maoclusions that dogs we see in dogs from class 1 to 4. Cats also commonly.
Can have a cordal malocclusion. And this is particularly seen in British short patients, and we think it results in British short hairs from these abnormal chunky mandibles that they have, which causes a very close contact between the cusps of the maxillary 3rd and 4th premolars with the oral mucosa adjacent to the mandibular premolars and molar tooth. And what happens is we get a range of traumatic injuries of the mandibular teeth and mandibular oral mucosa.
So in this picture of the patient, we can see that we have some foveas or little indentations in the gingiva. And then we've got the beginnings of some little proliferative inflammatory lesions which we call pyogenic granulomas. There are two main treatment options for these maoclusions.
Sadly, patients don't grow out of these maoclusions, and they can actually persist or get worse through life. And if left untreated, they'll result in end stage irreversible periodontitis of the mandibular teeth. Treatment options are really nicely summarised in two papers.
One of them was written by Reel in the Journal of Veterinary Dentistry in 2014, and the other is written by Margarita Grachis in JFMS, which is now open access, in 2014. So freely available. She wrote a lovely summary, about coralaloclusions in cats.
And what we know is that extraction of the offending maxillary teeth will result in Cure or, regression of these pyogenic granulomas and mucosal lesions in around 90 to 100% of patients. There is another treatment option which avoids extracting what are otherwise healthy maxillary premolar teeth, and that's called indontoplasty. And this is a simple reshaping of the cusps of the maxillary teeth that are causing the traumatic injury.
When we perform adontoplasties, we're deliberately injuring the enamel and dentin of these teeth. So it's important that if this treatment option is elected, that we then etch the exposed dentin and seal those open dentinal tubules with an unfilled light cured resin after we've performed odontoplasty. So aonopacity from these papers is successful in 75 to 100% of patients.
So it's a really good treatment option for these cats. That means that they get to keep all of their teeth. So how do we know if a patient actually requires treatment?
It's definitely true that some of our patients can have what we would deem to be a maoclusion, but they may or may not need treatment. In order to assess whether they might need treatment, we need to define whether the mallocation that we're seeing is what we call traumatic. So, they're defined as being traumatic.
If the abnormal position of the teeth is resulting in soft tissue ulceration or indentation. And we also define an occlusion as traum as traumatic if the way that the teeth are meeting is abnormal and therefore we will end up with With a concussion injury of one or more teeth. We also might consider that the patient might require treatment in order to remove the dental interlock that results from a class 2 maoclusion in a puppy, which can end up preventing normal jaw growth.
If we perform preventative. Or interceptive orthodontics to extract the maocluding deciduous mandibular canines in a class 2 maoclusion. We can then allow the patient to express their full genetic potential and potential mandibular jaw growth without it being hindered by the relationship between the mandible and maxilla when the patient has their mouth closed.
We might also deem the patient to require treatment if that maoclusion is resulting in pain, and that might not be obvious that a maoclusion is is causing pain. If we can see ulceration of oral mucosa. Is that all indentations of the oral mucosa.
We need to make the assumption that that patient is painful when they're closing their mouth. And we might also consider performing interceptive orthodontics, which is strategic extraction of one or more teeth to allow more room for the permanent teeth to erupt normally. So this is usually where we'd be extracting deciduous teeth that are incorrectly positioned in order to provide room for the permanent successes to erupt normally.
And, a lot of the treatment that we perform is based around trying to enable permanent teeth, permanent canine teeth to erupt in a normal location or to avoid a permanent canine maloclusion or to preserve the canine teeth ultimately, when these patients are undergoing treatment. So why is it important to preserve these canines? Well, as you can see in the picture on the right of this cocker spaniel who's growling at another dog, this cocker spaniel is giving a warning sign by flashing their canine teeth.
It's showing the other dog how big its canine teeth are, and therefore threatening it with, with injury. So, being able to show their teeth is an important part of behavioural signalling. Cats do this as well.
The teeth and tooth roots are of significant structural importance in the region of the jaws in which they're located. There was an excellent study in the Journal of Veterinary Dentistry in 2018 that showed that the K92 roots make up to 35% of the structure of the mandibles in the region in which they're located. The Interdigitation between the maxillary and mandibular canine teeth and other teeth as well also helps to stab stabilise lateral jaw excursion and prevent maloclusion when patients are chewing.
There is some lateral mobility in the temporary mandibular joints in dogs and to a lesser degree in cats. So the relationship of the teeth and the interstigation helps, prevent this lateral excursion when it's not wanted. And I think we all would like to avoid canine tooth extraction or extraction of other significantly important teeth if we can, because surgical extractions are no fun, especially when the teeth is essentially the teeth in question is healthy.
. Surgical extraction of healthy mandibular canines always comes with a risk of causing jaw fracture. Obviously, careful extraction with the aid of radiography helps to avoid that, but there is always a risk. What are the ethical considerations of treating these patients?
Yes, again, none of us like extracting deciduous teeth in puppies with maloclusions, but ultimately we are causing short term discomfort, which can be managed with appropriate analgesia in order to prevent shorter, medium, and longer term problems that also cause pain in these puppies. When we're thinking about treatment of these patients, we need to remember that, tooth position and jaw length is genetically predetermined. We'll go on to talk about that in The lecture on growth, and development later.
And therefore, these patients with manoclusions are likely, if allowed to breed to pass on their manoclusions to their offspring to some degree or another. So just as in any other Genetically inherited, abnormality, we should be recommending to clients that these patients with maloclusions are neutered at the earliest opportunity to avoid breeding. If these patients are undergoing modifications, for example, extractions, crown height reductions, or orthodontics, and especially for treatments such as orthodontics, where professional bodies such as the Kennel Club may not know that a patient has had an orthodontic modification.
If we're considering orthodontic treatment on pedigree dogs who are gonna be shown, then that treatment needs to be reported to the Kennel Club. Ultimately, for several of the maoclusions that we see, there are usually many treatment options, and ultimately extraction is the most straightforward but least rewarding. So what are our treatment options for deciduous tooth manoclusion?
I think the, the treatment that I most commonly perform in these patients is deciduous tooth maoclusion. For me, in my hands, guided by dental radiography and very careful extraction, this is a safe option. .
I am aware that there are A lot of very good dentists in general practise that have had training in these techniques and can carry out these techniques successfully in general practise on the patients that they see. But without appropriate training and without careful extraction technique guided by radiography. These are certainly procedures that carry a significant amount of risk, and if incorrectly performed, the biggest risk of extracting a deciduous mandibular canine tooth in a patient with an unirrupted permanent tooth is that you cause damage to the unerupted permanent tooth buds during the extraction, and this can lead to Enael defects, malformations, or in the most severe case, it can lead to loss of the tooth buds and the failure of eruption of the permanent tooth.
So in order to perform a deciduous tooth extraction, carefully, we need to take radiographs. Ideally, we take orthogonal views, as I've pictured here, so two views of the, of the deciduous canine. And that way we can work out where the permanent tooth bud sits relative to that deciduous tooth and therefore where we're not going to place our luxators or elevators when we're extracting this tooth.
In general, the permanent teeth erupt lingually or palatly. And measly. So therefore, in this patient pictured, I would perform very, very gentle and very careful laxation distally and buckily in order to extract this deciduous tooth.
And I would raise a flap to do that to remove a small amount of bone buckley to facilitate my extraction. What treatment options do we have for the permanent dentition? Broadly speaking, there are 3 categories, and those are exodontics or tooth extraction.
Endodontics, which is the preservation of teeth, where we broach the endodontic system. And then finally orthodontics, which is a movement of teeth. So within the exodontics category, not only do we include the, the surgical extraction of teeth to relieve a maoclusion, and that's usually the tooth that is causing the trauma to, either another tooth or the ginger or mucosa.
But I would also include other surgical procedures in this category that we might perform to relieve a maocclusion, such as a gingerectomy or a gingivplasty, which was described by Smith in the Journal of Veterinary Dentistry in 2013. That's a really lovely paper that describes the indications for performing a gingerectomy or gingeroplasty to relieve a maoclusion. And then, I would also include a simple coronaplasty within this category as well.
So that is a reshaping of one or more teeth that doesn't broach the pulp cavity in order to remove a traumatic contact. It's very unusual except in cats with a coral maoclusion that I will deem a coronaplasty to be a good treatment option for. Individuals with a maocclusion.
So then we have endodontics and orthodontics, and we'll talk about these different options. So when looking at orthodontics, we can use a range of different orthodontic treatments or devices in dogs and cats' mouths. And these devices, act in different ways and are categorised differently.
We call these devices active when the device is designed to exert a constant or continuous external force on a tooth. And we describe the device as passive if the device is only activated when the patient is closing their mouth. This is a form of self-regulated orthodontics, where essentially the patient regulates the amount of force that they put through the teeth.
We can describe a device as exerting an intermittent or a continuous force. That's fairly self-explanatory. And then we can describe the type of orthodontics that we're performing as either Preventative, interceptive, or corrective.
Orthodontics is preventative if we are. Removing a tooth. To prevent The abnormal occlusion or malocclusion of another tooth.
We can also describe that form of treatment as interceptive as well. And then it's corrective if we are moving, moving an abnormally positioned tooth. So What is the physiology behind tooth movement?
What is happening when we are applying orthodontic devices to the teeth? Well, we're causing complex signalling within the periodontal ligament, and that in turn results in remodelling of bone around the tissue, the alveolar bone. And what happens is that we get resorption of bone on one side of the tooth root.
And we get formation of new bone on the other side of the T3. We need to be careful with the amount of force that we exert on the tooth, because if the forces are too strong, what we'll end up creating is necrosis of the periodontal ligament. And instead of causing resorption and formation of new bone, if we get necrosis of the periodontal ligament, we'll end up getting, tooth ankylosis or tooth resorption.
So this is all mediated by signalling within the periodontal ligament and signalling between the periodontal ligament and osteocytes, osteoclasts and osteoblasts. So one of the most simple orthodontic therapies that we can use is what we call ball therapy. And this is really nicely described in quite an old paper now, written in 1999 by Lean Wehhart in the Journal of Veterinary Dentistry.
For therapy, I would say can be, Something that we use in permanent. Mandibular canine manoclusions. I wouldn't personally use ball therapy for the treatment of deciduous maoclusions because I think you have to use a weighted or substantial ball for this treatment and the risk that would come with that would be fracture of the deciduous teeth.
And an appropriately sized ball will provide a labial tipping force when played with to the mandibular canine teeth. We need to make sure if we're going to use ball therapy, that there is an adequate diastoma between the maxillary third incisor and the canine. For the mandibular tooth to tip into.
And in order to do that, the mandibular tooth really has to have a relatively mild maoclusion and not be sitting directly palatal to the maxillary canine tooth. Balls that I think are particularly good for this are the Kong balls, particularly the black heavy balls for, ultra chewers, or chuck it ultra balls, which are smooth, semi-hollow rubber balls. We need to choose an appropriate size, and that's described really nicely in a very heart paper and lean advocates choosing a ball that has a diameter, which is approximately, 50% of the distance between the tips of the canine teeth.
And this has is reported to have around about a 90% success rate in the right patients. An inclined plane is a different type of orthodontic device. This is a commonly performed referral procedure.
And it involves the fabrication of what is essentially a brace or a type of, A credit device on the maxilla or the roof of the mouth of a patient, and it's commonly used to orthodontically move permanent mandibular canine teeth that are incorrectly located. This is an intermittent passive force device, just like ball therapy is. And the forces are self-regulated by the patient in how much they close or the amount of force that they're closing their mouth with.
It's a temporary orthodontic device because we fabricate it in a patient, leave it in situ for the period of time that it takes for the teeth to move, and then remove it under general anaesthetic after the teeth have removed. An inclined plane needs to be placed bilaterally. If it's only placed unilaterally, what will happen is that device will cause the mandibles to shift towards the side that the inclined plane has been placed.
And in just the same way as ball therapy, it creates a tipping, a labial tipping force to move the mandibular permanent canine tee labially. And there's a pub a paper that's been published recently on this technique in Frontiers in 2023 by Taylor Eau. Which define the success rate of an inclined plane treatment within a median period of.
Point, which is really good. So, which patients are suitable for this treatment? Well, we need to be able to move.
The mandibular canine tooth relatively simply, so it, it wouldn't be for patients with a really severe malocclusion. And we can either attempt to move the mandibular canine tooth into its normal position between, in that sciastema between the maxillary third incisor and canine tooth. Or for really severe class 2 manoclusions, where the mandibular canine tooth is actually closer to the distal part of the maxillary canine tooth when the mouth is closed, we can consider moving the mandibular canine teeth with an inclined plane into a position caudal or distal to the maxillary canine teeth.
I don't like doing this because I don't think it's physiologically normal for patients to have this occlusion. But ultimately, this can result in saving the mandibular canine teeth from being extracted and, creating an a traumatic occlusion for the patient. I usually only consider orthodontic devices in patients that are less than a year old.
It's not impossible to move orthodontically move teeth in patients that are older, but it's definitely more challenging in older patients, the periodontal ligament is narrower and it's less springy, so it's less easy to move teeth. It can be more complicated and much slower in older patients. So, generally, I tend to restrict orthodontic treatments to patients that are less than a year old.
So this is what an inclined plane looks like. We fabricate them from a bisacral composite, which is a type of chemical cure. Composite.
It comes in an automix syringe with two pastes that get mixed together as the paste is dispensed through a syringe tip. And it takes around about 3 minutes for this type of material to set once it's been applied to the mouth. So we apply this material to the Maxillary canine teeth, the first premolar, and the 2nd and 3rd incisors.
And then once the material has set, we then shape this to create a ramp. In that diastema between the maxillary canine and the incisor. And the ramp will accept the tip of the mandibular canine tooth.
And as the dog's mouth is closed more and more and more, it will tip the tip of the canine mandibular canine tooth labially into a normal position dictated by the shaping of, of those ramps. So this is a patient that I performed this procedure on. This is called a patient called Griff.
In order to apply an inclined plane, the patient needs to have completely erupted permanent dentition. And if there are any retained deciduous teeth, these need to be extracted. So Griff had an adequate diastoma to accept the mandibular canine tooth, and it was a relatively simple movement to, that we needed to perform to move the mandibular canine tooth into an a traumatic position.
And this is what we managed to achieve with Griff. The device that I fabricated moved. That maxillary, the mandibular canine0 into position between, into a normal position between the maxillary third incisor and the maxillary canine.
There were no complications. The inclined plane stayed in place for 6 weeks, and then we removed it under general anaesthetic again. Patients do tend to get a very small amount of gingivitis or mucositis in the region that the inclined plane is applied, but this resolves really quickly once the inclined plane has been removed, and it's completely reversible.
The inverse of this treatment is to apply what we call temporary crown extensions to the mandibular canines which are shaped. To contact the, the maxilla in a way that creates a labial tipping force or a buckle tipping force on the mandibular canines. So this was really pioneered by Sig Staley and described in the Journal of Veterinary Dentistry in 2018.
AI achieved really good success rates for treating permanent maloclusions, of the mandibuna canine teeth in this paper with a 98.5% success rate. He did have complications that weren't included within this success rate.
So around about 20% of patients, had Mandibular canine teeth at the end of treatment that weren't quite what we call self-retaining and sitting in an overlapping position in that diastoma. And in 12.5% of patients in this paper, they either had fracture of the crown extensions or they required adjustments of the crown extensions during treatment.
And this is another type of passive intermittent force device. So the patient regulates the amount of force that's applied to those mandibular canine teeth, and the force is only applied when the mouth is closed, which is why we call it intermittent. So if you want to know more about that, head to 6 paper on the general veterinary dentistry, .
My, my own personal experience with temporary crown extensions is that I've had more than one patient fracture the crown extensions, and one patient fractured both the crown extension and the tooth itself, which necessitated a much more invasive treatment. So I tend to prefer an inclined plane, in preference to temporary crown extensions. And then we have what we call our active force devices.
I use these very rarely. I've probably used them in one or two patients, and I think patient selection for active force devices, which are There are more similarity to the sorts of braces that are used in humans. We need to choose our patients really carefully.
They need to be very compliant patients that are easy to handle, that are friendly. And, we also need to think about how close the clients are to the surgery because they may need to come back for several checkups. So these are Active force devices.
Technically, they are intermittently providing a force because, when the elastics are first applied to move the teeth, they will constantly They will constantly Create a force on the teeth to which they're applied. But as the teeth start to move and the Elastics are under less tension, then that force will decrease until we change the elastic. And most commonly in dogs and cats, we would use an active force device for treatment of what we call lance canines.
So that's our meioverted maxillary canine teeth. And we create a device in the mouth whereby the elastic or power chain needs to be replaced every 1 to 2 weeks to reactivate the force applied to the tooth. So this is what that looks like in situ.
We have an anchor unit, which are teeth to which the chain is anchored that are designed not to move. And usually this is the 4th pre-molar and first molar in a dog. And then, the anchor units is Attached to the maxillary canine via an elastic chain.
And either the elastic chain is fixed to the maxillary canine using what we call a snowman, which is a blob of composite on the tip of the tooth, or using a metal button applied to the maxillary canine tooth. We apply force by shortening. The length or the number of holes, between the anchor unit and the maxillary.
Canine tooth on that elastic chain. And the clients have to change this on a regular basis at home. For any orthodontic devices, I usually track how my cases are doing by asking owners to send photos to us every 2 weeks, with an expectation that movement should take usually 4 to 8 weeks, but can range from 2 to 8 weeks.
And the appliance is removed once the teeth are in a normal self-retaining position. I usually then recommend radiographs 4 to 6 months post-vi removal to ensure that we haven't moved these teeth too quickly or caused any permanent damage to the teeth or tooth roots, to check that the teeth are still vital, and developing normally and that there's been no tooth resorption. We need to manage client expectations.
Teeth don't always move the way that we want them to. You know, orthodontics isn't perfect even in human patients. Inclined planes and temporary crown extensions can need to have minor adjustments made to them.
They can break, which may necessitate further treatment or replacement of the devices. Placement of the devices requires an initial anaesthetic, but we also need to anaesthetize our patients to remove these devices as well. And there is definitely a risk of breaking or fracturing teeth when the orthodontic devices are removed from our patients.
However, those risks are usually small. And then we need to make sure that the clients understand that they'll also need to come back for follow-up radiographs to ensure continued tooth vitality, and that we haven't caused tooth resorption or tooth malformation during tooth movement. And then our final treatment option for patients with lingualally displaced mandibular canines is crown height reduction combined with vital pulp therapy.
What we're aiming to do when we perform this treatment is to reduce, essentially accept the position of the, the abnormal position of the mandibular canine teeth where they are, and then to reduce the height of the mandibular canine tooth or teeth, so either unilaterally or bilaterally, to take those teeth out of their traumatic occlusion. And in order to do that, we normally reduce the height of the crown of the mandibular canine teeth to level with the 3rd incisor teeth. We then aim to make the surface of the crown of the tooth flat rather than pointed, so that when it contacts the roof of the mouth, it creates less trauma.
And there was a lovely study written on the outcomes of vital pulp therapy in a huge number of cases by Nina Lewatinen. This was written in 2014. And it shows that vital pulp therapy is a really successful treatment when performed correctly.
And, I think success rates of around about 92% were achieved. So, it's combined with vital pulp therapy, the crown height reduction. And what this means is that we're deliberately broaching the pulp or the endodontic or the living part of the inside of the tooth when we're doing this.
So in order to complete treatment, this This needs to be it's virtually one of the only sterile procedures that I perform in dentistry. And following the crown height reduction, we perform what's called a partial pulpotomy. So we remove part of the pulp that's left, so that we can place a special multi-layered filling to maintain the health of the pulp.
And Hermetically reseal the tooth again. So we place a multi-layered restoration or white filling. So this treatment is, just as in most of the other treatments I've described, indicated for severe class 2 maocclusions.
And I tend to favour this treatment when I think it's not going to be possible to orthodontically move the teeth or where the client doesn't want us to perform orthodontic movement. This procedure does require follow up. It's an invasive treatment and When we describe the failure rate as being 8%, what we mean is that The multi-layered filling and pul pulpotomy that we perform can cause permanent endodontic disease or loss of tooth vitality in 8% of patients, with this technique.
And we'll see that in some patients very soon after this technique has been performed, and other patients can have a much more delayed failure, i.e. Delayed loss of vitality.
So if owners are consenting to this treatment, they also need to consent to follow-up radiographs at 3 months and 18 months postoperatively. To detect when things are going wrong, because as we all know, our patients are really rubbish at showing signs that they have oral discomfort or pain. And, bang on time, that is a roundup of treatment options and classification of Manulesians.
If you've got any questions, feel free to drop us an email at Eastcot vets. Thank you.