Meet Dr. O’Neill and the Staff

Twin Aspen Staff FunDr. Larry J. O’Neill and Dr. Brian Richter are the first to admit that their professional and courteous staff are the secret to success.

From the Administrative Staff to Clinical Assistants to the Dental Hygiene Department, each member of Larry’s team shares one common goal: to make your trip to the dentist as stress-free and enjoyable as possible.

Throughout his 30-plus years in dentistry, Larry has made it a point to treat his clients as a part of the family.

The environment in his office is fun and lighthearted. On a typical visit you might encounter a singing staff member or you might get your order in on the morning coffee run. The staff’s real strength lies in its unsurpassed experience and clinical skills. As Expanded Duty Clinical Assistants, each assistant has the high-level training needed to handle any type of dental service with professionalism and care. Once you’ve experienced the friendly, customer-first care of Larry’s highly-trained staff, you’ll know why Dr. O’Neill’s office has been so highly praised by both patients and peers.

Clinical Assistants

Our clinical assistants, Tiffany,  Lindsey and Audrey are expanded duty trained to place fillings and perform advanced procedures with a gentle touch.

Dental Hygienists

Rebekah, Courtney and Mandy, our dental hygienists, not only care for your smile, but enjoy hearing about how your day is going.

Administrative Staff

At our front desk, Dana, Suzanne, Mike, and Jo will ensure your appointments are on time and that your questions are promptly answered. Our personable staff keeps you involved in your care and respects your time.

As of January, 2016 Dr. Brian Richter bought Twin Aspen Dental, check out his page by clicking his name. That means Dr. O’Neill is setting his sights on retirement at some point here in the future, despite his repeated denials and “no comments”. Our patients won’t notice the difference, as we have the same staff and the same commitment to quality and technology!

Why not make an appointment and come meet us?

Larry O’Neill — A Passion for Dentistry

“The practice of dentistry is perfect for me. It is both a vocation and an avocation. I love every aspect of the practice. The relationship my staff and I and our patients enjoy is very gratifying. I look forward to being in the clinic every day. No day is boring. Every day is different because we do many different kinds of treatment. I feel our patients are all part of the staff family. Many of our patients feel the same way. We enjoy a free-wheeling style in the practice discussing movies, theatre, food, sports, music with our patients.

During the last thirty plus years, I’ve learned how to keep the atmosphere in the clinic fun and relaxing. Even kids love us. We keep it fun, but we underscore that fun with serious dedication to the science of dentistry. I love studying new techniques and materials and implementing the best of those in the practice. Keeping current is critical to our success. We have spent hundreds of thousands of dollars to keep this practice state of the art. Some doctors buy boats and motorcycles and plasma TVs; I buy lasers! We are currently building a new clinic that will take advantage of these new technologies to provide ever superior service to our patients.”

This is Larry O’Neill. Instead of retiring from the military to fish and ski, Larry loves dentistry so much he opened a private practice in historic downtown Parker. While he still fishes and skis, his consummate passion is dentistry.

A native of Portland, Oregon, Larry chose dentistry because he liked the multiple disciplines of medical, biological and physical sciences dentistry requires. And he wanted to be his own boss.

He earned his dental degree from the University of Oregon Dental School in Portland where he won awards for scholarship, graduated third in his class and was appointed to a U.S. Army dental internship program.

Larry then embarked upon a 26-year military dental career which started in Fort Sill, Oklahoma — where he served a general practice residency at Silas B. Hayes Army Hospital — and took him to California, Germany, Hawaii, Virginia, Texas and Korea — where he served as commander of a mixed peacetime and wartime dental organization in environments from hospitals and dental clinics to MASH-like tents in the mud — and finally back to Denver.

The Army gave Larry expertise in every aspect of dentistry which he brings to his practice today — oral surgery, general anesthesia, operating room techniques, full-mouth reconstruction and restoration, treatment of TMJ (temporomandibular joint dysfunction) and headaches — even forensic dentistry. During his tour of duty in Washington, D.C., he participated in the forensic identification of 287 soldiers and aircrew who had died in an airplane crash in Gander, Newfoundland.

During this time, he also built dental clinics, developed funding requests, bought equipment and developed future concepts of dental operations for both peace and war.

After one more tour of duty in Germany to command the world’s largest dental organization, more than 100 dentists and 600 dental personnel in 17 communities and 22 clinics — he returned to Denver to command the regional dental organization here.

In 1998, he woke up one morning and knew it was time to retire, so he did — and immediately went to work as an associate in a practice half of which he bought in 2002.

Larry has brought huge new capabilities to his new practice and expanded it from providing cleanings and simple fillings to placing dental implants and rebuilding entire mouths — not to mention his leadership and his commitment to the importance of community health and health education.

His vision is to grow into a new modern facility within three years and maximize the technology available to make dental care safer, more efficient and better and hire an associate dentist to work with him. He has already begun that quest with the incorporation of new technology into his practice and the renovation of his office.

Larry doubts he will ever completely be out of dentistry. “I love working with my hands, the art, the science and the relations with the people we treat,” he says. Eventually, Larry wants to teach dentistry and work in free dental clinics providing pro bono care for those who need it. For now, he’s where he wants to be doing what he wants to do.

Memberships and Awards

Dr. O’Neill was named one of America’s Best Dentists in 2004.


  • “A Clinical Evaluation of Electronic Root Canal Measurement” – Journal of Oral Surgery, Oral Medicine, Oral Pathology: Sep 73
  • “Soft Tissue Echymosis Secondary ” – Journal of Oral Surgery, Oral Medicine, Oral Pathology: Sep 74
  • National Emergency Medical Evacuation System A Proposal Coauthored), Published by National Defense University Press: 1989
  • “A Preclinical Model for Exodontia” (Coauthored), Journal of Dental Education: June 1992


  • President, Army Constituency, Academy of General Dentistry (1990 1992)
  • President, 38th Parallel Dental Society, Seoul, Korea (1989 1991)
    President Elect, Army Constituency, Academy of General Dentistry (1988)
  • Member, American Dental Association Special Committee on Young Dentists (1986 1987)
  • Member, American Dental Association Accredited Standards Committee MD 156 (1985 1988)
  • Secretary, Army Constituency, Academy of General Dentistry (1985 1987)
  • Membership Chairman, Army Constituency, Academy of General Dentistry (1984 1985)
  • Vice President, Mid Pacific Dental Society (1982)


  • Colorado State Boards – 1997
  • Certifying Board of General Dentistry – 1987
  • Master of the Academy of General Dentistry – 1984
  • Fellow of the Academy of General Dentistry 1981
  • Federal Services Board of General Dentistry 1980
  • Oregon State Boards 1972


  • U.S. Army Surgeon General’s “A” Proficiency Designator, 1993
  • Commandant’s Writing Award, ICAF, 1989
  • Joint Chiefs of Staff Research Award, ICAF, 1989
  • Membership Chairman Award, Academy of General Dentistry, 1985
  • Mosby Book Award for Scholarship, 1973


  • American Dental Association
  • Academy of General Dentistry
  • Pierre Fauchard Academy
  • Omicron Kappa Upsilon Honorary Dental Society
  • Delta Sigma Delta Dental Fraternity


  • Legion of Merit (Three Oak Leaf Clusters)
  • Meritorious Service Medal (One Oak Leaf Cluster)
  • Army Commendation Medal
  • Army Achievement Medal (Two Oak Leaf Clusters)
  • Army Service Ribbon
  • National Defense Service Medal (with Bronze Star)
  • Overseas Ribbon (3 Device)
  • Order of Military Medical Merit
  • Expert Field Medical Badge