A concussion injury is an injury to the periodontal ligament, or to the nerve and blood vessel tissue at the tip of a tooth’s root, sustained by a forceful impact to the tooth. An injury to the tooth-supporting structures without increased mobility or displacement of the tooth, but with pain to percussion.
Etiology
• It can occur from a direct blow to the tooth.
• A blow to the lower jaw that forces the upper and lower teeth together rapidly.
• Or from biting forcefully on unexpectedly hard food.
Diagnostic sign
• Absence of swelling, drainage or tender lymph nodes
• Absence of fever or malaise (feeling poorly)
• Absence of significant X-ray findings (if the condition has been present long enough, the ligament space around the tooth can appear noticeably enlarged).
• The tooth may or may not be sensitive to cold, but is usually not sensitive to heat or sweets.
• The patient usually confirms having bitten down hard on something, or having sustained an impact force to the tender tooth.
• Absence of cracks, and absence of tooth decay in the tooth, which generally appears to be intact.
• Over time, the tooth may discolor or darken. Sometimes the tooth will undergo “calcific metamorphosis”, meaning that the tooth’s root canal space may calcify partially or completely closed.
• Pulpal necrosis (i.e. death of the soft tissues inside the tooth) is uncommon (3% in some studies) with a concussion injury.
Percussion test –Tender to touch or tapping.
Mobility test
–No increased mobility.
Visual signs
–Not displaced.
Pulp sensibility test –Usually a positive result the test is important in assessing future risk of healing complications. A lack of response to the test indicates an increased risk of later pulp necrosis.
Radiographic findings
–No radiographic abnormalities. The tooth is in-situ in its socket.
Radiographs recommended
–As a routine: Occlusal, periapical exposure and lateral view from mesial or distal aspect of the tooth in question. This should be done in order to exclude displacement.
Treatment is symptomatic
• Usually there is no need for treatment.
• Allow the tooth to rest to promote recovery of trauma to the PDL andapical blood vessels.
• Observe clinically for colour changes in tooth.
• Usually recovery occurs within six months.
• Monitor pulpal condition for at least 1 year.
Patient instructions
• Soft food for 1 week.
• Brushing with a soft brush and rinsing with chlorhexidine 0.1 % is beneficial to prevent accumulation of plaque and debris.
Follow-up
• Clinical and radiographic control at 4 weeks, 6-8 weeks and 1 year.
Prognosis
• Usually prognosis is good.
• Good healing following an injury to the teeth and oral tissues depends, in part, on good oral hygiene.
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