Dr. McMillen received his dental degree from Georgetown University. Graduating in the top of his class, he also received the McCole Award for Excellence in Childrens Dentistry. After graduation, he completed a years internship program in Pedodontics at Childrens Hospital, Washington DC.

He received his orthodontic degree from Columbia University which is considered to be one of the finest orthodontic programs in the country. In addition, Dr. McMillen successfully completed a year of advanced TMJ study at Tufts Dental School, Boston, Massachusetts. He also served as an Assistant Clinical Instructor at Tufts Dental School. Dr. McMillen served as Chairman of the Insurance Council of Rhode Island Dental Society and is a member of the American Association of Orthodontists. He was also the President of Rhode Island Association of Orthodontics, an honor of recognition from his colleagues and a testament to the quality of his practice.

In recognition of his outstanding and meritorious contributions to the art and science of Dentistry, Dr. McMillen was made a Fellow of the International College of Dentists. The Convocation and Induction Ceremony was held on September 28, 2007.

The International College of Dentists is a not-for profit organization, which awards fellowships to dental professionals for conspicuous and meritorious service to the profession of dentistry. Fellows in the college continually strive to maintain and elevate the dignity of the profession through the highest standards of ethical and professional conduct and are enjoined to recognize their responsibility to participate in the affairs of society as citizens in their community and throughout the world.