Mary Egan graduated from Dublin Dental Hospital Trinity College in 1985. She acquired her own London practice in 1988, treating both NHS and private patients. She started specialist training at the Eastman Dental Hospital and completed her postgraduate degrees in Endodontology with Distinction in 1999. Mary taught part time at the Eastman Dental Hospital before returning to Ireland. She established her private practice limited to Endodontics in Waterford in 2000. Mary later opened a second clinic in Wexford.