Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Seek emergency medical care for difficulty breathing or swallowing, rapidly increasing facial or neck swelling, bleeding that does not stop with pressure, or new neurological symptoms such as confusion, fainting, or repeated vomiting.
Contact the dentist promptly if pain or swelling is getting worse, the tooth becomes darker, a gum bump develops, pus or a bad taste appears, fever occurs, or the tooth or splint becomes increasingly loose.
Follow-up timing varies with the injury.
Deep fractures, displaced teeth, root fractures, and replanted teeth usually require repeated checks.
The article also says
Keep all recommended dental visits even if pain and swelling improve.
At these visits, the dentist may assess color, pain, mobility, bite, gum health, root development, and pulp response.
Repeat X-rays may be needed to look for infection, resorption, changes in the supporting bone, or healing around the root.
Follow instructions for brushing, eating, mouth rinses, splint care, and physical activity.
The injured area generally needs careful cleaning because plaque around a splint or sore gum can interfere with healing.
Avoid using the injured tooth to bite hard foods until the dentist says it is safe.
Every sign above is quoted from the sofidex article on Broken or knocked out tooth. If you are not sure, err upward — it is always reasonable to be checked.