Colin Baxter

Veterinary Dentistry: A Clinician’s Viewpoint Abstract: This is a clinician’s view of the current state of veterinary dentistry at the level of the general practitioner across the different species. An indication of the work done and the hazards commonly encountered are covered. Clinical Relevance: To increase awareness within the dental profession of the current state of veterinary dentistry. Dent Update 2013; 40: 386–390

Veterinary dentistry has come a long way over the last few decades. This is because veterinarians have become more interested in what is happening in their patients’ mouths with an increasing awareness of systemic effects of dental and oral diseases. There has also been an increasing availability of suitable products and instruments to deal with the problems encountered. Also clients, the owners of the animals presented, are more aware of what can be done and demand a more conservative approach rather than just accepting that extraction is the only option. Horses’ teeth have always played an important part in their management and welfare. If a horse cannot eat properly, or is quidding (dropping food out of its mouth while eating), for example, it would soon lose condition and be less efficient as a work horse. The horse has had an important place in society at all levels and also as a war animal. Dentition of equines is also used as a method of ageing them for purposes of insurance and selling. It is calculated by

Colin J K Baxter, BVM&S MRCVS, Partner, Nantwich Veterinary Group, Nantwich Veterinary Hospital, Crewe Road End, Nantwich, Cheshire CW5 5SF, UK.

386 DentalUpdate

the shape of the tooth, the appearance of various grooves and ‘spurs’ on the teeth, as is the wear on the occlusal surfaces. Literature concerning the equine dentition extends back through the centuries. Extraction of human teeth was a traumatic experience in historic times but imagine dealing with a horse requiring teeth to be extracted! Nowadays, the use of regional nerve block anaesthesia, with or without sedation, or even under general anaesthesia, facilitates the safe access to the mouth by the veterinarian, if more than just basic dentistry is to be performed. Veterinary surgeons and Equine Dental Technicians (EDTs) maintain equine teeth with the use of large instruments and power tools, where appropriate. ‘Filing’, ‘Floating’, ‘Rasping’ all denote the use of abrasive instruments to reduce the height of exposed teeth to ensure a comfortable and functional bite. Extraction using punches and hammers, spurs removed using dental pincers, all requiring a degree of physical strength, are still used, but currently we also see teeth being endodontically treated in some instances. Dental and oral pathology in the horse can be extensive (Figure 1).1 Veterinary dentistry has also moved forwards as our clients expect us to do more for their pets, our patients. In 1988, a group of veterinary surgeons in the UK rose to the occasion and the British Veterinary

Dental Association was founded. In the USA, a similar interest group had been established in 1977. Europe followed with its own society in 1992 with the formation of the EVDS. Our patients offer us a huge range of challenges and opportunities to advance dental knowledge. First, all there are the many different types of teeth to be treated. The morphology varies considerably. They can be homodont, where all the teeth look the same general shape, as in reptiles, dolphins and sharks. Heterodonts have more than one general shape represented in the dentition, such as incisors, canines, premolars and molars. There are monophyodonts (one set of teeth, eg dolphins, porpoises and Beluga whales), diphyodonts (two sets of dentition, deciduous and permanent, eg dogs and cats) and polyphyodonts (many sets, eg sharks, elephants and manatees). Radicular and aradicular hypsodonts, or even combinations of these, may be found within a single mouth. There really is no point in putting a prosthetic crown on a tooth that is continually erupting, unless the restoration can be worn down at the same rate as its natural neighbours, as otherwise its occlusal neighbour will be subjected to abnormal forces. However, since dogs are diphyodont, radicular anelodonts, prosthetic crowns can be created with June 2013

© MA Healthcare Ltd. Downloaded from by on January 1, 2018. Use for licensed purposes only. No other uses without permission. All rights reserved.


success for the permanent dentition. Endodontic therapy can also be done if there is apexification and a complete root.2 Ironically, in teeth not in occlusion but continually erupting (elodonts), some form of endodontics may be appropriate to prevent pulpar necrosis and the total loss of a tooth after trauma. For example, in the Babirusa pig there are four very large canines continually erupting, of which the two upper canines penetrate through the nasal plane due to the naturally rotated position of the teeth, and all are vulnerable to trauma. If these are fractured,

Figure 1. Giraffe skull showing abnormal wear and osteomyelitis. This is similar in appearance to the same conditions in horses.

Fractured canine

then the risk of infection is great and temporary restoration is required to fill the cavity, which may be 1 cm in diameter, to ensure their continued growth is unimpaired (Figure 2). Dental morphology is varied from species to species but the general nomenclature is similar. The veterinary dentist has to contend with incisors, canines, premolars and molars. Some have particular names such as ‘carnassials’ (UPM4 and LM1 in dogs), ‘tusks’ in elephants, which are their lateral upper incisors, and ‘wolf tooth’ which is an upper first premolar in the horse. Virtually all our patients, except equines, require a general anaesthetic to allow us to examine closely and treat dental or oral conditions. A preliminary examination can, of course, be done by holding and manipulating the head to allow visualization. The teeth are identified using a ‘Modified Triadan System’. This is, as the name suggests, similar to the human version. Numbers 1, 2, 3, 4 are used to denote upper right quadrant, upper left, lower left and lower right, respectively. Numbers 5, 6, 7, 8 are used to allocate the deciduous teeth in diphyodonts following the same sequence as previously. However, since there are generally more teeth in the mouth compared to human counterparts, the teeth acquire the numbers 01 to 11 or above, as appropriate.

Normal upper canines

Protrusion into socket

Figure 2. Babirusa pig with fractured lower left canine 304. Note normal upper canines protruding through nasal area.

June 2013

So ‘204’ is the upper left canine, 109 is the upper right first molar, and so on. We follow the rule of ‘4’ and ‘9’ in heterodonts, where the canine tooth is always number 4 and the first molar is always a ‘9’. This allows for animals with inherently missing teeth to have their dentition properly annotated. An example is the domestic cat, which is missing the first upper premolar so that the first premolar visible is actually a ‘6’. The total number of adult teeth in the dog is 42, the cat 30, rabbits 28, and chinchillas 20; horses can vary from 40 to 44. Diet has played an important part in the state of human dentition and is believed to be equally as important in animals. The length of fibre in the horse’s diet can cause changes in the degree of wear on the occlusal surfaces. The presence of adequate calcium and silica in the rabbit and rodent diet is also essential for normal growth with smooth surfaces and essential occlusal wear, otherwise the teeth ‘overgrow’ and malocclusion occurs. This may be lifethreatening. The veterinary dentist has to assess the clinical picture and advise either dentistry under general anaesthesia, with advice for the changes to the diet, or euthanasia. Because the cheek teeth of rabbits are continually erupting (aradicular hypsodont elodont), in many cases the occlusal surface erosion is not rapid enough

Protrusion and mandibular thinning

Figure 3. Rabbit skull showing abnormal wear of occlusal surfaces. Note mandibular thinning with protrusion of cheek teeth and also ‘root’ protrusion into eye socket rostrally.

DentalUpdate 387 © MA Healthcare Ltd. Downloaded from by on January 1, 2018. Use for licensed purposes only. No other uses without permission. All rights reserved.


and soft tissue damage occurs, typically to the tongue and cheek.3 As well as this overgrowth, they also get protrusion of the ‘root’ penetrating the mandibular bone and becoming palpable as protrusions, or they may push into the bony eye socket and cause retrobulbar problems (Figure 3). The flow of tears in the tear duct may also be interrupted by this overgrowth and cause epiphora or dacryocystitis and, ultimately, complete blockage. The patient presents with infected eyes and the owner may be unaware of an underlying dental problem. Dogs, cats and the so called ‘small furries’ (rabbits, chinchillas, etc) have a plethora of conditions of interest to the veterinary dentist. The instruments and materials we use are directly from human dental suppliers or are variations on the theme, supplied by specialist veterinary suppliers. The endodontic instruments can be the same as in human practice, but increasing up to 120 mm files for larger carnivores and even large industrial drills for specialist elephant work! For domestic pets, the use of digital radiography is fairly commonplace and the use of dental X-ray machines is essential. The position of the teeth allows for very few radiographs to be taken in a ‘parallel’ position and, more usually, dental veterinarians depend on a bisecting angle technique to ensure any distortion is minimized whilst getting the

entire relevant tooth on the plate. Every veterinary practice will deal with extractions and most should be able to scale and polish with skill. Home products specifically for the veterinary market are available; so veterinary toothpastes are available that can be swallowed and don’t froth as much as human versions. The correct diet for dogs and cats is a contentious issue with followers of ‘complete’ diets and ‘natural’ diets vying for attention. Irrespective of this, the discerning pet owner wishes for his/her pet to live a long and healthy life, and this includes having better and healthier teeth and gums than in previous generations. The food companies may alter the composition of the kibble to make it more fibrous, for example to aid removal of plaque. Some may add triple polyphosphates to act as chelating agents for mineral deposits. Some chews are manufactured with a particular shape to encourage chewing to remove plaque mechanically. Water additives are also available to reduce the bacterial load within the oral cavity, with varying degrees of success. Mouthrinses, again able to be swallowed, can be used, as well as topical gels and additives in the drinking water. All are available to reduce the retention of plaque and calculus and to slow the onset of gingivitis and periodontitis. Owners present us with pets

Figure 4. Chronic periodontitis in a dog. Note calculus, debris and plaque deposits.

388 DentalUpdate

with halitosis, fractured teeth, pets unable to eat, pets wanting to eat but reluctant to do so, or with teeth in malocclusion. Pets may have severe chronic gingivitis or chronic periodontitis (Figure 4). There are also the jaw fractures, tumours, palatal and lip defects, impacted/intruded and avulsed teeth, the tongue injuries and defects, the inherited and developmental defects and the ubiquitous foreign bodies and stick impaling injuries. These all require investigation with surgery, extractions, scaling and polishing, etc, under general anaesthesia, as appropriate. Some teeth may be fractured and can be treated endodontically and functionality restored. Composites and compomers colour-matched to the original enamel can be used to give the aesthetic finish. Not every practice can offer this service, but there are specialist veterinarians who can. The state of the patient’s mouth may be pointed out to the owner at the clinical examination, such as at a first, or subsequent, vaccination or a general health check, so that the owner is aware of some primary oral issue themselves. Malocclusions through faulty eruption, genetics or fractured jaws or teeth may be identified.4 Genetic counselling could be given to try to improve the overall health of the breed and prevent the defect being perpetuated. However, some malocclusions are readily corrected and can enable the dog

Figure 5. Bite Plate or Incline Plane attached to upper canines to move crowns of lower canines laterally.

June 2013 © MA Healthcare Ltd. Downloaded from by on January 1, 2018. Use for licensed purposes only. No other uses without permission. All rights reserved.



Figure 6. ‘Lance tooth’ in Shetland sheepdog: 204 upper canine is rostrally and horizontally deviated.

(particularly) to eat properly and in comfort. One such condition is described as ‘base narrow canines’, whereby the lower canines are displaced lingually and thus the crown tips traumatize and penetrate the palate. This can be corrected using an ‘incline plane’ or ‘bite plate’. This is created so, gradually, through the dog’s own efforts of closing its mouth, the canines reposition to a normal occlusion (Figure 5). Another condition is ‘lance tooth’ where the upper canine has erupted and is pointing rostrally in a horizontal plane (Figure 6). Typically associated with Shetland sheepdogs, this can be corrected using orthodontic brackets and elastics. Some creativity of attachment may be required owing to the varying shapes of the dentition. The optimum time for the majority of orthodontics, in this vet’s opinion, is when the dog is about seven to nine months of age. At this age, the appliance will be effective and only take two to three months in total. Cats can be susceptible to severe gingivitis in conjunction with viruses such as Calicivirus, Feline Leukaemia virus, or Feline Immunodeficiency virus. This can lead to exaggerated inflammatory response requiring radical treatment regimes. Feline Odontoclastic Resorptive Lesions (FORLs) are well recognized by the profession too.5 Restoration has been attempted in previous years but it is generally agreed that multiple extractions is the treatment of choice. Handling facilities for the

390 DentalUpdate

Figure 7. Orang-utan under general anaesthesia for dental examination.

veterinary dental patient, as well as general anaesthesia, have to be considered too, as some zoo animals may be a considerable risk to handlers, eg Orang-utans weighing up to 150 kg (Figure 7), or a Scimitar Oryx with long sharp horns. Adequate safe handling facilities and induction in minimally stressful environments are essential when considering a general anaesthetic for a giraffe, with its life-threatening risks of fractured neck or limbs caused during induction or recovery. Safety of access by the veterinary dentist and assistants is paramount, whether that is on a straw-bedded floor in a zoo or dealing with a fractious family feline in a state-of-the-art veterinary hospital. Our patients may weigh from 100 g to over 1000 kg. Obviously, while working with primates, several zoonotic considerations have to be addressed too. Clinicians may spread viruses to the primates and are also vulnerable in return. Veterinary dentists are an adaptable group of people and will tackle the usual scale and polish, extractions and dental charting. Some will do vital pulpectomies, endodontics with full root canal therapy, restorations, bridgework, prosthodontics and orthodontics. Implantology is still in its veterinary infancy but is being used on occasion. False teeth have been placed in dogs’ mouths as early as 1947 and sheep in the 1980s. Perhaps it is modern ethics that prevent their more prevalent use today! Where to next? As dental materials improve for use in the human

arena, veterinary surgeons will try them on animals and, if suitable for particular conditions, they will be added to the armamentarium. Pet insurance, if the owner is lucky enough to have a policy that covers dentistry, has also played its part in the preservation of teeth, as it has enabled endodontics and restoration to be carried out, where previously extraction would have been the only option.

References 1. Anthony J, Waldner C, Grier C, Laycock A. A survey of equine oral pathology. J Vet Dent 2010; 27(1): 12−15. 2. Tutt C. Endodontic Therapy. Small Animal Dentistry. A Manual of Techniques. Oxford, UK: Blackwell Publishing, 2006. Ch 10: pp214−227. 3. Redrobe S. Surgical procedures and dental disorders. In: BSAVA Manual of Rabbit Medicine and Surgery. Paul Flecknell, ed. Gloucester, UK: BSAVA, 2000: pp130−133. 4. Verhaert L. Developmental oral and dental conditions. In: BSAVA Manual of Canine and Feline Dentistry 3rd edn. Tutt C, Deeprose J, Crossley D, eds. Gloucester, UK: BSAVA, 2007. Ch 6: pp77−95. 5. Gorrel C. Odontoclastic resorptive lesions. In: Veterinary Dentistry for the General Practitioner. Edinburgh, UK: Saunders, 2004. Ch 11: pp119−129. June 2013

© MA Healthcare Ltd. Downloaded from by on January 1, 2018. Use for licensed purposes only. No other uses without permission. All rights reserved.

Veterinary dentistry: a clinician's viewpoint.

This is a clinician's view of the current state of veterinary dentistry at the level of the general practitioner across the different species. An indi...
137KB Sizes 0 Downloads 0 Views