Saint Apollonia (?-249) is a Christian saint and martyr, she is the patron saint of dentists and people with tooth problems including toothaches. She lived in Alexandria, Egypt; she is the patron saint of dentists because of how she was martyred, by having all her teeth pulled out. She is usually depicted holding a pair of tongs sometimes with a tooth in them and the martyr's palm. Her feast day is February 9.

Further Reading

http://en.wikipedia.org/wiki/Saint_Apollonia
http://www.dentalhealth.ie/apollonia/