GREELEY & NISTA ORTHODONTICS Accessibility Statement

GREELEY & NISTA ORTHODONTICS is committed to facilitating the accessibility and usability of its website,, for everyone. GREELEY & NISTA ORTHODONTICS aims to comply with all applicable standards, including the World Wide Web Consortium's Web Content Accessibility Guidelines 2.0 up to Level AA (WCAG 2.0 AA). GREELEY & NISTA ORTHODONTICS is proud of the efforts that we have completed and that are in-progress to ensure that our website is accessible to everyone.

If you experience any difficulty in accessing any part of this website, please feel free to call us at (302) 475-4102 or email us at and we will work with you to provide the information or service you seek through an alternate communication method that is accessible for you consistent with applicable law (for example, through telephone support).

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I was born to be an Orthodontist!

I have tremendous passion for our profession and the patients we serve. I feel privileged to be part of a profession that makes such a profound difference in people’s lives. My staff is vitally involved in this process and helps support our patients at every step of their journey. Straightening teeth is part of what we do but the entire GNO team strives very hard to help people enrich their overall lives.

We view our practice like one big happy family. We reach out to help each other and our patients in any way possible. We cherish the friendships we develop and constantly strive to encourage our patients to be the best that they can be. Our office is a warm, nurturing, fun place to be. There is no other profession we would rather be in. We love what we do! That’s what you can expect from GNO.


Our Doctor:

Dr. John Nista

Family and Community

Dr. Nista’s personal interests include golf, fishing, skiing and cooking. He is an active member of the Knights of Columbus and is currently participating in Creative Mentoring. He, too, is a past President of the Delaware State Dental Society. Dr. Nista is married with two children, Jason and Sarah. Being the oldest of five children, he particularly enjoys working with young children.


Dr. Nista attended dental school at the University of Pittsburgh, completed a General Practice Residency at the Veterans Administration in Dayton, Ohio and completed his orthodontic training at Albert Einstein Medical Center in Philadelphia. He has had extensive training in surgical jaw procedures. Dr. Nista joined Dr. Greeley in 1990 and a special relationship was born!

Our Doctor:

Dr. Leah Yi

Family and Community

Her mom is an orthodontist, she is married to a general dentist and her sister is a pediatric dentist!
She likes tennis, plays the cello and has a shameless addiction to hot Cheetos
She has one child, Emelia


College Degree: Cal Berkley in California
Dental Degree: University of Pennsylvania
Orthodontic Certification: University of Pennsylvania