Equine dental care: the latest developments [H&H VIP]

  • Modern equine dental care has moved on from simply smoothing the rough edges towards highly sophisticated methods of prevention, diagnosis and treatment. Neil Townsend MRCVS outlines some of the latest developments

    Equine dentistry is undergoing a renaissance. Central to this revival is what we’ve learnt over the past 15 years about the fundamental anatomy of horses’ teeth and the diseases they can suffer. Much of this research has been led by Professor Paddy Dixon of the University of Edinburgh.

    We now have a greater understanding of the patterns of communication between the many pulps — the blood and nerve supply — of the equine tooth, thanks to recent research from German authors using micro computed tomography (CT). Complex modelling techniques have also helped determine the forces on the cheek teeth and incisors while the horse is eating.

    Alongside this technical progress is the recognition of equine dentistry as a field of veterinary medicine. A vast array of quality equine dental CPD — continuing professional development — can now be accessed by vets and practising technicians known as paraprofessionals. In addition, high-level veterinary qualifications and further accredited exams for both vets and equine dental technicians (EDTs) have become available.

    These developments have undoubtedly led to enhanced standards of equine dental care and consequent improvements in welfare.

    Open wide
    The saying “prevention is better than cure” applies as much to dentistry as to any other subject.

    A thorough oral examination using a gag to open the mouth, and involving a bright light source and a dental mirror is now considered vital. This usually takes place under sedation, unless the patient is very compliant.

    Oral endoscopy is now commonplace in many veterinary clinics and has the advantages of providing magnification and a means of recording the examination.

    We know that subtle abnormalities that are missed or ignored can turn into long-term, chronic clinical problems which can subsequently be difficult and expensive to resolve.

    An example of this is where a small amount of food material is trapped between teeth. If left untreated, this may progress to inflammation of the gums (gingivitis) and gum disease (periodontal disease).

    Oral endoscopy can aid early diagnosis and appropriate treatment, but may also identify causative factors such as minor displacements of the cheek teeth, which can then be addressed at an early stage.

    Historically, the treatment for fractured incisors was extraction. Many of these can now be saved using techniques used to treat disease of the tooth’s pulp (endodontic techniques) derived from human dentistry.

    Following thorough clinical and radiographic examination, selected fracture cases may be suitable for restorative treatment. This might entail pulp capping, where the exposed pulp is preserved with a permanent, protective covering, or the surgical removal of a portion of the pulp (partial pulpotomy).

    Dealing with decay
    Restorative techniques are also now used to treat selected cases with infundibular caries — decay in the central “cup” of an upper cheek tooth.

    Caries of the infundibulae of the upper cheek teeth, particularly the first molar, can lead to a midline fracture of the tooth that necessitates its removal. Often, the tooth directly opposite is also affected.

    Following cleaning and sterilisation of the decay, the tooth can be restored with a resin composite to reduce its chances of fracture in the future.

    Infection (pulpitis) of a cheek tooth is not uncommon in horses. Identification of the affected tooth involves a combination of clinical signs, oral examination and diagnostic imaging.

    With the exception of selected cases, the treatment for an infected cheek tooth is extraction. The basic technique has remained unchanged since Victorian times, although the instruments used have become more refined.

    With the appropriate use of sedatives and local nerve blocks, extraction should be the treatment of choice — provided there is enough of the erupted part of the tooth (the clinical crown) for it to be grasped with extraction forceps.

    If the tooth cannot be removed in this way, alternative techniques are required. One option is lateral buccotomy, where the tooth is extracted via a surgical incision through the cheek. Another surgical technique is dental repulsion, where the tooth is pushed from its socket using a dental punch.

    Both are associated with high rates of complications and have been superseded by the recently developed, minimally invasive technique known as transbuccal extraction, or MTE.

    Future developments
    Over the next five to 10 years, procedures may become available that will allow infected cheek teeth to be treated without being permanently removed. Orthograde endodontic therapy (similar to human root canal therapy) of infected cheek teeth is already being performed in selected cases, although the technique has not yet been critically appraised.

    Where infection of the cheek teeth is apical, affecting both the root area and the surrounding tissue, it is now possible in some cases to extract and re-implant the tooth.

    First, the tooth is extracted orally and a small portion of its apex is removed to allow access to the pulp canals. The pulps are then removed and the canals are sterilised and filled with dental cement.

    Finally, the apex is sealed and the tooth is re-implanted into the socket and temporarily cemented to the adjacent teeth while the ligaments re-attach to the tooth socket.

    Equine dentistry is continuing to evolve. With greater understanding of the intricate anatomy of the horse’s mouth and response to treatments, further treatment techniques should become more widely available.

    This article was first published in Horse & Hound magazine (15 January 2015)