Permanent Dentition: Uncomplicated Crown and Crown-root Fractures: Infractions, Enamel Fractures, Enamel-dentine Fractures, Enamel-dentinecementum Fractures
To provide a review of current practice for the treatment of uncomplicated crown and crown-root injuries to permanent teeth.
After reading this chapter the reader should be aware of the appropriate treatment for fractures of the crown of permanent teeth not involving the pulp.
The exact WHO definition of these injuries is shown in Table 1-1.
These are the commonest injuries to the permanent teeth and are usually sustained as a the result of falls, bicycle, scooter, skate board and roller blade accidents, and contact sports. The commonest cause in children and young adolescents is an accident during play that usually involves tripping up or bumping against another child. In teenagers and adults, such injuries are more commonly associated with contact sports, fights, and road traffic accidents. Boys are affected twice as much as girls. If treatment is delayed or considered inappropriate there can be significant effects on the prognosis for pulpal vitality, especially when there is dentine involvement. The pulp requires protection against thermal irritation and from bacteria entering the dentinal tubules. Restoration of crown morphology stabilises the position of the tooth in the arch.
Infraction is the term for crazes and cracks of enamel with no loss of tooth substance.
Enamel fracture describes the injury where there is loss of enamel but no involvement of dentine.
Enamel dentine fracture describes the injury where there is involvement of dentine but not the pulp.
Infraction lines are seen as crazing or cracking of enamel and are often highlighted by transillumination of the crown, in particular with a curing light. Infraction may be the only evidence of injury after trauma. Infractions should, however, alert the clinician to the need for regular monitoring and review.
Initial assessment of fractures involving enamel and enamel and dentine should include the clinical and radiographic parameters as outlined in the ‘trauma stamp’ in Table 1-2 and discussed in Chapter 1. This ensures that the appropriate clinical and radiographic examinations are completed at each review. The colour of a crown is often best assessed from the palatal aspect. Remember that it is possible for some discolouring haemorrhage to occur into the dentinal tubules and for the pulp to retain vitality. If this is the case, then on successive review one would not expect a change in colour. Persistent or continued darkening would suggest necrosis. Tenderness to percussion (TTP) and tenderness to digital pressure in the buccal sulcus are very reliable indicators of apical pathosis, as is the presence of a sinus. Mobility could suggest either pathosis or resorption, or a root fracture. Vitality (pulp sensitivity) testing is not reliable. An EPT which has a quantitative value, compared with ethyl chloride testing which has either a positive or negative outcome, is of greater value in subsequent follow up examinations, which might reveal numerical changes over time. Thermal tests become more important after the immediate post-trauma period when it is important to assess pulp changes such as reversible and irreversible pulpitis. A negative response to pulp sensitivity testing in the absence of any other sign should not be regarded as an indication for pulp extirpation.
In the future we may be able to use ‘doppler’ probes that measure blood flow within a crown. This will be a very reliable method of ascertaining vitality on the basis of a pulp blood supply and the need to extirpate a pulp. However, such probes are very expensive at present and not available for routine use in everyday clinical practice.
Sealing of infraction lines with unfilled resin after acid etching may be indicated. This will prevent the uptake of extrinsic stain from foods and drinks. However, the unfilled resin may be prone to discolour over time. If infraction lines penetrate to the dentine, then the tooth may be sensitive on etching.
Either recontour the tooth or restore the missing piece of enamel with a resin-bonded composite. The distal incisal corner of a tooth can often be recontoured, but the mesial incisal corner may require restoration to maintain an aesthetic appearance. Recontouring can often be achieved with composite finishing discs without the need to resort to burs.
Early protection of exposed dentine is essential to prevent adverse effects caused by oral fluids, certain foods and bacteria. This can be achieved by a resin-bonded composite resin or compomer ‘bandage’. Glass-ionomer cements do not have the physical properties to reliably withstand function on an incisal edge. An hermetic seal of injured dentine is critical to maintain the prognosis of the pulp (Tabl/>