Traumatic injuries to the face are common, often resulting in soft tissue lacerations, tooth fracture, damage to the periodontium and jaw fracture. This presentation will cover management of tooth fracture and injuries to the periodontium. Tooth fracture may affect the crown, the crown and root, or just the root. Injuries to the periodontium may result in subluxation, luxation and avulsion of the tooth

Tooth fractures are classified as complicated if the fracture line exposes the pulp to the oral environment and as uncomplicated if they do not involve pulpal exposure. Complicated tooth fractures always need treatment as exposed pulp will become inflamed and eventually undergo necrosis, with the inflammation spreading from the pulp to involve the periapical area.^1,2,3 The earliest radiographic evidence of periapical pathology is widening of the periodontal ligament space in the apical region. This widening is due to inflammation of the apical periodontal ligament. If untreated, the apical periodontitis progresses to involve the surrounding bone resulting in destruction of the bone, which is replaced by soft tissue. This is evident as an apical rarefaction on a radiograph. The soft tissue may be granulation tissue (periapical granuloma), cyst (periapical or radicular cyst) or abscess (periapical abscess).^2,4 The periapical cyst usually occurs as a sequel to the periapical granuloma.^2,3 Periapical cysts enlarge due to the osmotic gradient set up between the lumen of the cyst and tissue fluids in the surrounding connective tissue. An untreated periapical abscess can lead to complications such as osteomyelitis and cellulitis through spread of the infection. A fistulous tract opening on the skin or oral mucosa may develop.^2,4

Pulp and periapical lesions may be entirely asymptomatic or excruciatingly painful. The periapical granuloma and periapical cyst rarely cause severe discomfort but they may undergo exacerbation and develop into a periodontal abscess, which usually is an extremely painful condition. The clinical signs indicative of periapical pathology are often insidious and not noticed by the owner. It is often only after completion of treatment that the owner reports a dramatic improvement in the animal's general demeanour.

Crown fractures are obvious visually. A primary tooth with complicated crown fracture should be extracted to avoid damage to the adjacent developing permanent tooth. A permanent tooth, if unaffected by periodontal disease, can be treated by means of endodontic therapy. If the tooth has periodontitis or the fracture is too extensive, then extraction is the treatment of choice. In fact, with complicated crown fractures extraction is preferable to no treatment at all. Immature permanent teeth are a special consideration in that viable pulp is necessary for apexogenesis (continued root growth and closure of the root apex). Thus, a specific endodontic procedure, namely partial pulpectomy and direct pulp capping, is indicated if the pulp is still vital. Necrotic immature permanent teeth also need endodontic treatment if they are to be maintained. The aim of treatment is to achieve apexification (closure of the root apex in the absence of further root development). In most instances, necrotic immature permanent teeth should be extracted. Uncomplicated crown fractures may also require treatment as the exposed dentine tubules allow communication between pulp and oral environment and can thus result in inflammation or death of the pulp. An uncomplicated crown fracture usually requires minimal treatment, e.g., removal of sharp edges with a bur and sealing of the exposed dentine with a suitable liner or restorative material. However, such fractures do require monitoring (clinical examination and radiography) at regular intervals to ensure that the pulp remains vital. If pulp and periapical disease develop, the tooth requires either extraction or endodontic therapy.

Treatment of crown and root fractures depends on how far below the gingival margin the fracture line extends. If the fracture line does not involve the pulp and does not extend more than 4–5mm below the gingiva, restorative dentistry can be performed. If the pulp is exposed, endodontic therapy needs to be performed prior to restoration. If the fracture line extends more than 5 mm below the gingiva then the tooth should usually be extracted.

Root fractures may be horizontal or oblique. In general, horizontal root fractures have the best prognosis. A tooth with a long axis fracture is an absolute indication for extraction. Abnormal mobility, horizontal or vertical, of a periodontally sound tooth may lead you to suspect a root fracture. Definitive diagnosis of root fractures depends on radiography. The choice of correct treatment i.e., fixation or extraction is only possible based on a definitive diagnosis. Fixation is by means of ligature wire and acrylics. Radiographic monitoring of treatment is required.

Trauma may also result in injuries to the periodontium, resulting in subluxation, luxation and avulsion of a tooth.

Subluxation occurs when the periodontium has been damaged so that the tooth is loosened in its alveolus. Tooth mobility is limited to increased horizontal movement; the tooth has not been displaced in a vertical direction. No treatment is indicated except soft food for a week. Pulp vitality of the traumatized tooth does need to be monitored, as pulp necrosis is a common complication of luxation.

Luxation of a tooth can be either in a vertical direction, i.e., intrusion or extrusion, or in a lateral direction. Treatment consists of repositioning and fixing the tooth in its correct location. Fixation is achieved by means of ligature wire and acrylic. Pulp vitality needs to be monitored to detect and treat complications.

An avulsed tooth has been totally luxated from its alveolus. It needs reimplantation and fixation (by means of ligature wire and acrylics) as soon as possible as the result of reimplantation depends on the viability of the periodontal ligament. As the ligament dehydrates it becomes less viable. Hence, the two most important factors determining the result of treatment are the length of time the tooth has been out of its socket and the medium in which the tooth has been stored during this period. The sooner an avulsed tooth is reimplanted, the better the prognosis. The best medium in which to store an avulsed tooth is saline, or if not available, milk. An avulsed tooth will undergo pulp necrosis and requires endodontic therapy, which is usually performed at the time the fixation appliance is removed, i.e., after 4–6 weeks. The endodontic therapy (pulpectomy and rootfilling) needs to be checked radiographically. This is generally after 6 months.

References

1.  Stafne EC, Gibilisco JA. The pulp cavity. In: Stafne EC, Gibilisco JA, eds. Oral Roentgenographic Diagnosis 4th Ed. Philadelphia: WB Saunders. 1975:61–70.

2.  Shafer WG, Hine MK, Levy BM. Diseases of the pulp and periapical tissues. In: Shafer WG, Hine MK, Levy BM, eds. A Textbook of Oral Pathology 3rd Ed. Philadelphia: WB Saunders. 1974:433–462.

3.  Gorrel C, Robinson J. Endodontics in small carnivores. In: Crossley DA, Penman S, eds. Manual of Small Animal Dentistry. Gloucestershire: British Small Animal Veterinary Association. 1995:168–181.

4.  Stafne EC, Gibilisco JA. Infections of the jaws. In: Oral Roentgenographic Diagnosis 4th Ed. Philadelphia: WB Saunders. 1975:74–85.