Tooth Fractures
Introduction
Tooth fractures may affect the crown, the crown and the root or just the root.
Fractures are termed complicated if there is exposure of the pulp.
All teeth are susceptible to fracture, but in the mature dog and cat, maxillary canines are most commonly broken, followed by the mandibular canine, the maxillary fourth premolars, and incisors. In the immature dog less than 6 months old, deciduous canine teeth commonly fracture.
Causes of fracture include: chewing on metal fences or gates, hard chew toys, stones, ice cubes, horse and cow hooves. Road traffic accidents and other trauma can also lead to fractures.
Crown Fractures
Crown fractures are usually obvious visually.
Enamel fracture: if only the enamel is fractured, this will appear as chips in the enamel surface.
The treatment of choice is to smoothe any sharp edges with fine diamond burs or sanding disks in order to prevent trauma to the lips and tongue.
Radiography should be obtained to check for any apical root fractures and a follow-up radiograph should be performed within the year to check for periapical pathology.
Enamel and dentin fracture: this provides a direct pathway for bacteria to the pulp via the dentinal tubules. Pulp exposure should be evaluated for by probing with an explorer tip with the animal under general anaesthesia. Radiographs should be taken to evaluate the root.
- Indirect pulp capping: covers exposed dentin with glass ionomer cement followed by crown restoration. Follow-up radiographs are taken at 6-monthly intervals.
- Direct pulp capping: the dentin is removed and the pulp is covered with calcium hydroxide or glass ionomer cement, followed by crown restoration.
Enamel and dentin fracture with pulp exposure: if the pulp is exposed endodontic treatment must be performed or the tooth must be extracted. An untreated exposed pulp leads to necrosis of tissue in the direction of the root apex.
Crown-root fracture
A crown-root fracture involves the enamel, dentine and cementum. It can be further classified into complicated or uncomplicated.
Root fracture
A root fracture involves dentin, cementum and pulp and is generally complicated.
Some root fractures which are reasonably stable, horizontal and uncontaminated, may heal unaided with the pulp remaining vital. The alveolus acts as a natural splint which maintains the segments of tooth in close proximity.
If the fracture is unstable, the coronal segment of the fracture should be removed and the apical segment either extracted or treated endodontically.
Endodontic treatment
Treatment and prognosis of fractures depends on:
- The degree of displacement and mobility of the fracture segments
- The extent of contamination
- The amount of damage to the alveolar crest bone
For complicated fractures, endodontic treatment should be performed in adult animals.
Mature teeth have narrow pulp cavities and fully formed roots. Root canal treatment involves:
- Cleaning out the remaining pulp
- Shaping and disinfecting the root canal
- Filling the root
- Restoring the surface
Crown restoration
Fractures with pulp exposure require endodontic treatment but the prosthodontic build-up of the crown is optional.
It may be sufficient to simply close the fracture sites with composite resin.
Full crown restoration may be important for working dogs who rely on normally functioning teeth. It may also be of aethetic advantage in show dogs.
It may also be indicated to protect the tooth against further trauma. It will reduce the risk of further breakdown of the remaining tooth structure.
Restoration of the tooth structure may help prevent periodontal disease by preventing food entrapment in the gingiva.
Radiography should be performed regularly to check for periapical inflammation or bone disorders.
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References
Verstaete, F. (1999) Veterinary Dentistry: Self assessment colour review Manson Publishing
Gorrel, C. (2004) Veterinary Dentistry for the General Practitioner Elsevier Health Sciences
Bellows, J. (1999) The practice of veterinary dentistry: a team effort Wiley-Blackwell
Wiggs, R. (1997) Veterinary Dentistry: principles and practice Wiley-Blackwell