When a tooth is loose due to trauma, how long does it take for it to tighten up?

Depends: If the tooth is not fractured it may take 2-6 wks to tighten up.

No fixed time : Schedule per se. Was it splinted? Degree of looseness? Type of trauma? Please visit your dentist if you have not already. Hope this helps.

2 - 4 weeks: It depends on the degree of trauma. Most loose teeth require a splint to be placed for only 2 weeks. If the trauma is more severe, such as a fracture near the neck of the tooth or a severe intrusion, it may require splinting for 4 weeks and up to 4 months. It is important to seek dental care as soon as possible following a traumatic event to minimize further damage to the tooth.