A diseased or damaged molar that is beyond repair is best removed, but how? Neil Townsend MRCVS explains
Dental extraction can appear daunting to an owner. When performed by a suitably qualified and skilled clinician, however, with the correct equipment, it can be a routine procedure. Often, the patient does not have to stay in hospital, and time off following extraction is minimal.
The most common reason for removal of a molar (cheek) tooth is infection of its roots, termed apical infection.
Signs of infection can vary, dependent upon which tooth is involved. Generally, infection of mandibular (lower) cheek teeth creates a swelling on the bottom of the jaw, which may burst out into a draining tract (a surface wound). Apical infection of the front maxillary (upper) cheek teeth usually causes swelling in front of the facial crest – the bony ridge either side of the face. Because the back maxillary teeth have their roots within the sinuses, infection typically causes nasal discharge.
Teeth may become apically infected or require extraction as a result of fracture, advanced dental caries (decay), periodontal (gum) disease or a blood or lymphatic-borne tooth infection. Signs may be subtle, ranging from ‘quidding’, or spitting out, of long fibre in the case of infection, to tenderness over a facial swelling. Occasionally, a ‘dead’ tooth with open pulps (the soft, central area) is only identified during routine dental examination.
A detailed oral exam under sedation can give clues as to which tooth is involved, by identifying fractures, open pulps, dental caries and periodontal disease. This will also provide vital information about the infected tooth, notably the integrity of its crown and whether the tooth is already mobile.
Radiography (X-rays) are used examine the roots of the cheek teeth and the surrounding structures. A marker can be placed over any facial swelling beforehand, to see which tooth sits beneath it. Similarly, a probe placed into a draining tract will often go directly to the affected tooth.
Advanced imaging such as computed tomography (CT) can be useful in cases where radiography and oral examination fails to reach a diagnosis.
Extraction of cheek teeth should only be performed by a veterinary surgeon, unless a tooth is so loose that can be manipulated by the fingers – as is sometimes seen in geriatrics. A qualified equine dental technician (EDT) may then perform the procedure.
Oral extraction is usually the preferred starting technique where a portion of the tooth is present within the mouth. This is performed under sedation with a regional nerve block in place, along with local anaesthetic.
Right-angled elevators are used to separate the gingiva (gum) from around the tooth, and molar spreaders are placed between the affected tooth and those adjacent to it. These tools are gradually manipulated before being replaced with thicker instruments. Forceps are then secured to the tooth, which is further loosened by ‘wiggling’ until it can be lifted from its socket with a tool called a fulcrum.
Maxillary teeth fractured in the midline can be extracted orally – through the mouth – in many different ways. Each case should be considered individually; some clinicians prefer to loosen and remove the halves separately, while others glue the broken tooth together with dental resin and extract it in one piece.
Oral extraction most commonly fails due to further fracture of the tooth, usually due to pre-existing disease within it. A small portion of the tooth that is left may be loosened with right-angled picks and removed with forceps.
For teeth that are fractured below the gumline, a favoured technique is minimally-invasive transbuccal extraction (MTE). This must only be performed by vets with relevant further qualifications, in a clinic setting, using standing sedation and local anaesthesia.
A keyhole incision is made in the cheek and a small sleeve is passed through the skin into the mouth. Straight elevators are placed through the sleeve and guided around the tooth with the aid of an oral endoscope, to loosen the remaining tooth portion.
A hole is drilled into the tooth and a threaded pin is screwed into it, so that a slotted hammer used on the end of the pin can pull the tooth from its socket. The sleeve is removed and the incision is closed with skin staples.
Following the loosening of a tooth, a small pin can be inserted through the bone in order to push the remaining portion of the tooth into the mouth. Intra-oral division, where the tooth is divided into pieces with a rotating burr, may also be useful in selected cases.
After an oral or MTE extraction, the empty socket is usually ‘packed’ to prevent food accumulation. The packing material – gauze swabs, or dental putty – must be changed every one to two weeks until the socket has healed.
A draining tract may require daily cleaning until dry, while any skin staples are usually removed at the first packing change. Most horses can begin work again two weeks after extraction.
Ccomplications following these techniques are rare.
The most common is failure of the socket to heal adequately. If every fragment of tooth has been removed, this is usually due to a portion of dead socket bone, known as sequestrum, which may not become evident until three to four weeks post-extraction.
Recent research has shown this to be more common following mandibular extractions. Treatment involves removal of the sequestered portions of the socket with right-angled picks.
Extraction is generally more difficult the further back in the mouth the teeth are, as the space between them decreases. This is a particular issue in small ponies or miniature horses, since it is almost impossible to reach a hand to the back of the mouth.
Horses have ‘hypsodont’ teeth, meaning that they continue to erupt. A molar in a young horse can measure up to 10-12cm, which may be too long to pull into the mouth in its entirety. Cutting it into two may be necessary to allow delivery into the mouth.
Chronically diseased teeth can present challenges in addition to the risk of fracture; some lay down abnormal cementum (the surface layer) around their roots, becoming mushroom-shaped and extremely difficult to extract.
Of all the extraction methods, oral extraction has the lowest reported complication rate, of around 10%, dependent on study, compared with around 15%-25% for MTE. Both rates compare favourably to those for more complex surgical extractions or repulsions, however, performed under general anaesthesia. With these, complication rates can be as high as 60%.
Provided the tooth is removed successfully, and the socket heals without complication, an owner can expect the horse to recover fully with no further issues.
‘Fermenting food was visibly bubbling’
This eight-year-old thoroughbred gelding had a left-sided mandibular swelling, which was initially treated with oral antibiotics and anti-inflammatories. The swelling resolved but four months later burst out from the bottom of his jaw.
The gelding underwent a thorough oral examination at the equine clinic. All appeared normal at first glance, but, on closer examination, one of the tooth pulps contained fermenting food material that was visibly ‘bubbling’. Radiography was performed with a probe in the draining tract, revealing communication with the tooth roots and chronic infection.
With a mandibular nerve block in place and local anaesthetic injected around the tooth, the affected molar was successfully removed by oral extraction in around 40 minutes. The draining tract was cleaned, the socket was packed with a dental putty plug and the patient was allowed home.
The horse was back in work a fortnight later, and, by six weeks the socket was 80% healed. After three months, the mandibular swelling was barely noticeable.
Ref: 7 January 2021
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