Dr. Tiernan earned his Bachelor of Sciences degree at Saint Marys College. He went on to achieve his Doctor of Dental Sciences degree at University of the Pacific, San Francisco. He then completed his oral surgery residency at Highland General Hospital in Oakland, California.
Dr. Tiernan opened his private practice in September 1991. Dr. Tiernan is board certified with the American Board of Oral & Maxillofacial Surgeons. He is also a fellow of the American Association of Oral & Maxillofacial Surgeons and the International Congress of Implantologists. Dr. Tiernan is a member of the American Dental Association, the California Dental Association and the Redwood Empire Dental Society.