Alexander M. Reiter., Dipl. Tzt., Dr. med. vet., DAVDC, DEVDC
True emergencies in veterinary dentistry, oral surgery and oral medicine include the following: recent tooth fractures, tooth displacement injuries, fractures of the mandibular and maxillofacial bones, palatal trauma, thermal and chemical burns, temporomandibular joint disorders, lip avulsion, soft tissue lacerations, foreign body penetration/impaction, and pain causing the patient not to eat or drink.
Recent Tooth Fractures
Common causes of tooth fracture are trauma in dogs and advanced tooth resorption in cats. If the pulp is exposed as a result of traumatic tooth fracture, endodontic therapy is required (vital pulp therapy or standard root canal therapy). Another option is to extract the tooth. Indications for and techniques of endodontic therapy are further described in the proceeding note "Endodontics--what to do with a fractured tooth."
Tooth Displacement Injuries
Tooth displacement injuries result in damage to the attachment apparatus and loss of apical neurovascular supply. Luxation refers to clinically or radiographically evident displacement of the tooth within its alveolus. Lateral or extrusive luxation occurs most commonly and is often associated with fracture of the alveolus. Intrusive luxation is a rare complication associated with trauma that forced a tooth with periodontal disease into the nasal cavity, resulting in chronic rhinitis and nasal discharge. Surgical exposure through an intra-oral approach is required to remove the tooth. Avulsion (exarticulation) refers to complete extrusive luxation and occurs after automobile accidents, falls from great heights, fighting with other animals, or when a tooth gets caught in a fence. The teeth most commonly avulsed in dogs are the incisors and canine teeth.
Luxated and avulsed teeth require repositioning, stabilization, and endodontic therapy due to the likely loss of blood supply to the pulp. The success of reimplantation of an avulsed tooth is greatly influenced by the length of time that the tooth is out of the alveolar socket. Ideally, the avulsed tooth should be placed back into the socket immediately. If this is not possible, the tooth is placed in Hank's Balanced Salt Solution (Save-A-Tooth). Systemic antibiotic therapy is instituted until the patient can be seen by the veterinary dentist. If an appropriate storage medium is not available, the tooth can also be placed in fresh milk, which maintains the vitality of periodontal ligament cells for 3-6 hours.
Prior to reimplantation, the tooth is soaked in a doxycycline solution (1 mg in 10 ml sterile saline) for 5 minutes, and the alveolar socket is rinsed with sterile physiologic saline or doxycycline solution (do not curette the alveolar socket or tooth root surface). The tooth is repositioned, and any gingival lacerations are sutured. A semi-rigid splint is applied, allowing physiologic movement. Systemic antibiotic therapy is continued. Endodontic therapy is performed 1 to 2 weeks later; the necrotic pulp is extirpated, the root canal filled with calcium hydroxide paste, the access temporarily restored and the splint removed. Final root canal obturation with sealer and gutta-percha is performed in another 2 weeks.
Long-term calcium hydroxide treatment is used when the injury occurred more than 2 weeks before initiation of endodontic treatment or if root resorption is evident on dental radiographs. The calcium hydroxide is changed every 3 months, and the root canal is obturated when a radiographically intact periodontal ligament space and lamina dura can be demonstrated around the root. Rigid splinting would prevent physiologic movement, leading to dentoalveolar ankylosis and root replacement resorption. If endodontic treatment fails, inflammatory root resorption leading to rapid destruction of the tooth is an inevitable consequence.
Fractures of Mandibular and Maxillofacial Bones
Causes of fractures of mandibular and maxillofacial bones include trauma (motor vehicle trauma, falls, kicks, gunshot trauma and fights with other animals) and pre-existing disease (bone loss associated with severe periodontitis, oral neoplasia and metabolic abnormalities). Common sites for mandibular fracture in dogs include the region of the molars and the area distal to the canines. In cats, the mandibular symphysis and the condyloid process are frequently involved. Epistaxis, facial swelling, pain, crepitus, subcutaneous emphysema and asymmetry are common physical findings of fractures involving maxillofacial bones. Under general anesthesia, oral examination and diagnostic imaging are performed (dental and standard medical radiographs, computed tomography).
Initially, the mouth is flushed with dilute chlorhexidine, and loose teeth and small bone fragments are carefully removed. There are several techniques of treating jaw fractures:
1. Maxillomandibular fixation: If there is little segment displacement and occlusion has not been altered, fitting the patient with an adhesive tape muzzle may effectively provide dental interlock and adequate stabilization. Complications include dermatitis, heat prostration, dyspnea, and aspiration pneumonia. Occlusal alignment and stabilization of posterior mandibular fractures or chronic temporomandibular displacement may also be achieved with a bilateral bis-acryl composite bridge applied between upper and lower canine or carnassial teeth.
2. Circumferential wiring: Symphyseal separation or fractures near the mandibular symphysis, common injuries in cats with high-rise or motor vehicle trauma, can be repaired with a cerclage wire placed circumferentially around the two mandibles just caudal to the canine teeth. The wire should not be left in place for longer than 4 weeks.
3. Interdental wiring combined with an intra-oral resin-based splint: This is the preferred non-invasive technique for repair of jaw fractures and teeth present in fracture segments. The Stout multiple loop wiring technique is most commonly applied, using the dental crowns as anchor points. The teeth are then cleaned, polished with pumice, and acid etched. Self-curing bis-acryl composite is applied to the teeth via an applicator gun (along the lingual surfaces of lower teeth and buccal surfaces of upper teeth). Once the material has set, the appliance is trimmed and polished.
4. Transosseous (interfragmentary) wiring: This technique is very effective for fracture stabilization in edentulous areas of the lower jaw. Mucoperiosteal flaps on buccal and lingual bone surfaces need to be raised so that holes can be drilled through the mandible no closer than 3 mm to the fracture line, carefully avoiding tooth roots and the mandibular canal. A ventral approach to the mandibular body has also been described. Preferably, two wires are used in a triangular configuration.
5. Percutaneous (external) skeletal fixation techniques: At least two Kirschner wires or small Steinmann pins are placed into each fracture segment. Plastic tubing is then placed over the exposed cut ends of the pins, and while normal occlusion is maintained with the jaws closed, the tube is filled with self-curing acrylic or custom tray material.
6. Bone plating: Specialized expensive equipment is required, and significant soft tissue elevation is necessary for the placement of bone plates. It provides rigid fracture stabilization and rapid return to normal function. However, trauma to tooth roots and neurovascular structures may be a common complication.
7. Partial mandibulectomy or maxillectomy: When extensive trauma, infection or necrosis precludes fracture reduction or adequate fixation, surgical resection of the fractured segment may be considered. A salvage procedure for bilateral pathologic mandibular fractures in dogs with severe periodontal disease involves extraction of all diseased teeth and partial rostral or central mandibulectomy with bilateral advancement of the lip commissures.
8. 'Intramedullary' Pinning: This 'ancient' technique causes significant trauma to the neurovascular structures in the mandibular canal, does not provide any rotational stability, and is therefore not recommended for repair of mandibular fractures.
Post-operative considerations include adequate pain control and placement of an Elizabethan collar to prevent the animal from causing damage to the orthopedic device during the healing period. Orthopedic devices are removed following radiographic confirmation of fracture healing 3 to 6 weeks postoperatively.
Temporomandibular Joint Disorders
Temporomandibular joint luxation is more common in the cat than the dog and usually occurs unilaterally and in a rostrodorsal direction. Radiographs should be obtained to confirm the diagnosis and to eliminate other causes for mandibular displacement. Reduction is performed by inserting a pencil between the upper and lower carnassial teeth of the affected site, and gently forcing the mouth closed. This will accomplish a caudoventral movement of the condyle.
Open-mouth jaw locking with impingement of the mandibular coronoid process on and locking lateral to the zygomatic arch is a rare condition in dogs and cats. The patient usually presents with the mouth wide open, and a small protuberance from a malpositioned coronoid process can often be palpated impinged on or lateral to the zygomatic arch. In contrast to temporomandibular joint luxation with rostrodorsal displacement of the mandibular condyle, there is no tooth-by-tooth contact. Manual correction is achieved by opening up the mouth a little further, pressing the protuberance medially, and closing the mouth. Surgery is often required to prevent relapses, involving partial resection of the zygomatic arch and/or partial reduction of the coronoid process on the affected side.
Acquired palate defects are usually located in the hard palate and may be caused by various types of trauma, including falling from a great height, dog bites, electric shock, gunshots, penetration of foreign objects, and pressure necrosis.
Fresh midline palatal defects are often associated with high-rise trauma in cats. Although they may heal spontaneously in 2 to 4 weeks with conservative management, the benefit of managing the injury by approximating the displaced bony structures, followed by suturing of the torn palatal soft tissues, outweighs the risk of development of a persistent oronasal fistula. If the hard palate is widely separated, the gaping site is reduced with finger pressure, and interarcade wiring reinforced with bis-acryl composite is applied between the upper canine or incisor teeth.
Motor vehicle trauma or accidental stepping on the face by a person may cause a degloving injury to the upper or lower lip. Lower lip avulsion is most commonly seen in young cats. The wound is debrided, and the lip is replaced and kept in place with simple interrupted sutures. Large horizontal mattress sutures can be passed around the tooth crowns.
Soft Tissue Lacerations
Lacerations of the cheek, lip or tongue are carefully debrided and sutured closed. Multiple full-thickness tongue lacerations may occur after seizures or during recovery from anesthesia. They bear the potential for necrosis and may result in loss of significant amounts of tongue tissue.
Thermal and Chemical Burns
Electric cord injuries occur most often in young animals. Immediate pulmonary edema may be life threatening. It can take several days before the extent of local injury is clearly defined. Necrosis of the lips, cheeks, tongue, hard palate, gingivae, dental pulp and alveolar bone is common. The patient is initially managed conservatively, and the injured tissues are left to necrose. Management of wide-spread osteonecrosis or chronic oronasal fistula requires further surgery.
Possible causes for chemical burns are corrosive chemicals or gastric reflux. This is more common in dogs than cats. Therapy is copious lavage with water, followed by conservative management.
Foreign Body Penetration/Impaction
Linear foreign bodies caught around the tongue can saw into the lingual frenulum; treatment is removal of the foreign body.
Penetration of the oral and pharyngeal cavity may be due to animal bites or foreign bodies (e.g., stick injuries in dogs). Foreign body penetration can cause deep, contaminated wounds to the sides and root of the tongue, tonsillar crypts, floor of the orbit or pharyngeal walls. Management of these injuries requires surgical exploration, cleansing and, if appropriate, suturing. Foreign bodies remaining in the wound may lead to retrobulbar or submandibular abscessation and fistulation.
Acute and Chronic Oral and Masticatory Pain
Stomatitis is a disease seen largely in the adult domestic cat and is characterized by persistent chronic inflammation of the oral (and pharyngeal) mucosa. Research has provided further clues on the pathogenesis, but the etiology of this disease is not fully understood. Affected cats may present with a history of inappetence/anorexia and weight loss. Pain results from severely inflamed oral mucosae. Cats with stomatitis present a therapeutic challenge. The goal of treatment is aimed at controlling oral plaque and decreasing the inflammatory and immunologic response. Management of stomatitis includes professional oral hygiene, topical antimicrobial application, systemic antimicrobial therapy, anti-inflammatory and immunosuppressive medication, and selective tooth removal.
Masticatory muscle myositis (MMM) is an inflammatory disorder selectively involving the masseter, temporal, and medial and lateral pterygoid muscles of dogs. The nature of the inflammatory infiltrate, the clinical response to immunosuppressive doses of corticosteroids, and the identification of autoantibodies directed against myofibers in masticatory muscles strongly support an immune-mediated mechanism for MMM. Necrosis and phagocytosis are limited to the 2M myofibers in these muscles, and there is circulating IgG directed against the unique myosin component of these fibers. MMM can occur in any breed of dog, but young adult and middle-aged large breeds of dogs are most commonly affected. Three stages were described: an acute stage (firm painful muscle swelling/inflammation), followed by an asymptomatic stage (apparently healthy animal), which is then either followed by a chronic stage (muscle atrophy, skull-like appearance of the head) or a recurrent acute stage. Both clinical presentations are associated with difficulty or inability to open the mouth. Untreated episodes last 2-3 weeks. Relapses frequently occur in weeks or months. Diagnostic tests include 2M myofiber serum antibody titer and muscle biopsy. Initial treatment is performed with immunosuppressive doses of corticosteroids and slowly tapered over 8-12 months to the lowest possible alternate-day effective dosage. It is often necessary to maintain dogs on a low dose, alternate day corticosteroid therapy to prevent relapses.
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