Dr. John is a Long Island native and is thrilled to be back home practicing in New York. He grew up in Nassau County, and went to Chaminade. He then went to Boston University where he earned a B.A., M.A., and D.M.D. with honors. He subsequently completed a general practice residency at Penobscot Health Care/ Eastern Maine Medical Center where he earned an award for Clinical Excellence in Endodontics. He is particularly passionate about helping patients overcome barriers to dental treatment in a gentle and compassionate manner.

Following his residency he served fifteen years in Maine, New Hampshire, and Rhode Island in a clinical role, and also as Dental Director for Greater Portland Health. He also served as Adjunct Clinical Assistant Professor (Preceptor) for the University of New England School of Dental Medicine.

Dr. Fitzsimons is passionate about dental continuing education. He is a Fellow in the Academy of General Dentistry. He volunteers annually for the Yankee Dental Congress in Boston, the Mission for Mercy in Rhode Island, the Academy of General Dentistry Annual Meetings, and the Long Island Give Kids a Smile Event. He is a member of the American Dental Association, New York Dental Association, Nassau County Dental Association, Academy of General Dentistry, and the Special Care Dental Association.

When outside of the office he is busy with his wife Allison and son JP, born in 2024. They enjoy traveling and developed an interest in skiing in the years they lived in New England. He looks forward to meeting you in the office!