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OASECT has been innovating beautiful smiles with braces and Invisalign since 1958 in southeastern Connecticut. Their fun-loving and capable team represents a combined 271 years of experience with the practice! Two experienced Orthodontists and their team of dedicated staff are here to help answer all of your questions and to make you smile.

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Dr. Gregory Hack

Dr. Gregory Hack is a graduate of Brown University and the Columbia University School of Dental and Oral Surgery. Following the completion of a general practice residency at Lenox Hill Hospital in New York City, Dr. Hack pursued his orthodontic specialty training at the University of Connecticut Health Center, studying with Dr. Charles Burstone, the world-renowned expert in the biomechanics of orthodontics. He joined Orthodontic Associates in 1991.


Dr. Hack lives in Old Lyme where he has raised three children with his wife Barbara, a local physician. Dr. Hack is very engaged in a number of community Boards, and serves as President of the Old Lyme Rowing Association. The Hack family passion for rowing recently took them to the Rio Olympics, where they supported their son, who was stroke of the USA men’s eight!

Orthodontist & Affiliate Partner

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Dr. James M. O’Leary is a lifelong resident of Waterford, Connecticut. Based upon his own experience with orthodontics at age 12 and seeing firsthand how straight teeth and a great smile contributed to increased self-esteem and confidence, he chose to pursue a career in orthodontics. He is a graduate of the Ohio State University and Tufts University School of Dental Medicine in Boston, MA earning his DMD degree, Summa Cum Laude. Upon graduating from dental school, he went on to complete a comprehensive, 2-year orthodontic residency program at Tufts University. He is board certified by the American Board of Orthodontics. Dr. O’Leary takes a personal and caring approach to orthodontic treatment, making your experience in our office something you can truly smile about!


When he’s not treating patients, Dr. O’Leary enjoys spending time with his family, mountain biking, skiing, traveling and playing golf. He remains active in the local community, supporting the local schools and various charities.

Dr. James O'Leary

Orthodontist & Affiliate Partner