The persecution of Christians began in Alexandria during the reign of the Emperor Philip. The first victim of the pagan mob was an old man named Metrius, who was tortured and then stoned to death. The second person who refused to worship their false idols was a Christian woman named Quinta. Her words infuriated the mob and she was scourged and stoned.
While most of the Christians were fleeing the city, abandoning all their worldly possessions, an old deaconess, Apollonia, was seized. The crowds beat her, knocking out all of her teeth. Then they lit a large fire and threatened to throw her in it if she did not curse her God. She begged them to wait a moment, acting as if she was considering their requests. Instead, she jumped willingly into the flames and so suffered martyrdom.
There were many churches and altars dedicated to her. Apollonia is the patroness of dentists, and people suffering from toothache and other dental diseases often ask her intercession. She is pictured with a pair of pincers holding a tooth or with a golden tooth suspended from her necklace. Saint Augustine explained her voluntary martyrdom as a special inspiration of the Holy Spirit, since no one is allowed to cause his or her own death.
Sources:
https://www.franciscanmedia.org/saint-of-the-day/saint-apollonia/
