Modules
Module 4: Managing Dental Emergencies
4.2 Injury Classification

Injuries to primary teeth are classified in the same way as injuries to permanent teeth, with both dental and alveolar components. Some injuries may have only one of these components, but many involve both the teeth and the supporting structures. In deciding how to treat injuries to primary teeth, particularly injuries with an alveolar component, the dentist must consider the injury's potential impact on the developing permanent tooth.

The Ellis Classification System

Dental fractures are divided into the follows categories, based on the Ellis classification system:

  • Ellis Class I: These fracture involve the crown and extend through the enamel only. These teeth are usually non-tender and without visible color change but have rough edges.
  • Ellis Class II: These fractures involve the enamel as well as the dentin layer. These teeth are typically tender to the touch and to air exposure. A yellow layer of dentin may be visible.
  • Ellis Class III: These fractures involve the enamel, dentin, and pulp layers. These teeth are typically tender and have a visible area of pink, red, or even blood at the center of the tooth.

The Ellis classification system is still used in categorizing trauma to teeth. In many cases, enamel fractures can be left alone or smoothed to reduce rough edges. Occasionally, incisal corners (class I) can be restored, but they are prone to losing the composite owing to minimal retention. Enamel-dentin fractures (class II) are more often in need of restoration, and the treatment of choice is to use the appropriate celluloid crown form or strip crown. The crowns of these teeth should be etched and the entire tooth (rather than just the fractured angle) restored, to maximize retention of the composite. In other words, the entire crown is bonded with tooth-colored composite.

When the pulp is exposed (class III), it is necessary to perform pulpal therapy—either a formocresol pulpotomy (immature root apex) or a pulpectomy (mature root apex, followed by a composite crown). Root fractures are difficult to treat. A rule of thumb is that if the tooth is firm in the alveolus, it should be left alone. If it is clearly mobile, the coronal and apical portions should be removed. In these cases, try not to be overly aggressive with the apical root fragment so as to not damage the underlying permanent tooth.

Little evidence exists to guide the dentist in managing the immature primary tooth's pulp. Formocresol appears to be the medicament of choice. The open apex often precludes a pulpectomy. Calcium hydroxide is believed to be a stimulant for root resorption and should be avoided in any primary tooth pulp therapy.