Final answer:
Bluish-grey discolouration of the crown of an anterior tooth following trauma is most commonly due to pulpal hemorrhage. X-ray imaging may be used to evaluate the extent of damage and guide treatment. Other causes like external resorption, composite restoration, or bacteria are less likely immediately post-trauma.
Step-by-step explanation:
The bluish-grey discolouration of the crown of an anterior tooth following trauma is most often due to pulpal hemorrhage. When the soft tissue within the pulp chamber is damaged, blood can seep into the dentinal tubules and even the enamel, leading to this discolouration. Once stained, the dentin may remain discolored, which is visible through the translucent enamel. External resorption, discoloured composite restoration, and chromogenic bacteria are less likely to cause such discoloration immediately following trauma.
It is critical to consult a dentist for a proper examination, which may include an X-ray imaging to assess the extent of damage and to help in the diagnosis and subsequent treatment of the traumatized tooth. While the discoloration indicates a historical trauma or injury to the pulp, if the pulpal tissue is necrotized or infected, further treatment, such as a root canal or tooth extraction, may be necessary.