Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Go to an emergency department or call emergency services if:
Swelling affects your breathing, swallowing, speech, eye, or neck
You are becoming confused, faint, or severely unwell
Jaw or tooth pain occurs with chest pressure, breathlessness, sweating, or nausea
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Arrange an urgent, same-day dental assessment if you have facial or jaw swelling, fever, spreading redness, pus, or pain that prevents sleep or eating.
You should also seek urgent dental advice after a significant tooth injury.
3
Does any of this apply?
Book an appointment
Book a routine dental appointment if pain lasts longer than two days, keeps returning, occurs when biting, or comes with ongoing sensitivity.
You should also book if a filling has broken or a tooth has become chipped.
The article also says
A medical clinician can assess fever, spreading swelling, or symptoms that may not come from a tooth.
However, most dental causes need care from a dentist.
Every sign above is quoted from the sofidex article on Toothache. If you are not sure, err upward — it is always reasonable to be checked.