Meet Our Doctors
Jon M. Koeltl, D.D.S.
Dr. Koeltl has been a member of the practice for 10 years. He is an esthetic and restorative dentist.
Dr. Koeltl received a Bachelor of Science in Biology from University of California, Davis in 1997, and a Doctor of Dental Surgery from the University of Pacific in 2000. He completed the advanced education in General Dentistry Residency program in 2001. Dr. Koeltl also has 300+ hours continuing dental education at the Pankey Institute. Dr. Koeltl is a member of the American Dental Association, California Dental Association, and Contra Costa Dental Society, and is also a member of the Partnership Dental Study Group.
In his personal life, Dr. Koeltl and his wife, Cindy have lived in Alamo for 9 years where they are happily raising two young children. In his free time he enjoys reading, golf, football, and wine.
"We specialize in results focused comprehensive dental care. We have a wonderful team of specialist that we refer to for Endodontics, Oral Surgery, Periodontal Surgery, and Orthodontics. We believe that utilization of specialists, in conjunction with our restorative treatment, results in exceptional long lasting restorative care." - Dr. Jon Koeltl D.D.S.
Valerie N. Johnston, DDS
Dr. Johnston has been in private practice since 2000 and joined The Diablo Dental Group in 2006. Her passion is to provide the highest quality of dental care in a gentle manner. She is a general dentist with a wide range of expertise including restorative, esthetic, implant and children's dentistry.
Dr. Johnston is a graduate of the University of California at Davis where she earned a Bachelor of Science degree in Neurobiology and Physiology. She went on to graduate in 1999 from the University of the Pacific School of Dentistry with a DDS degree. She graduated with honors becoming a member of the TKO Dental honor society. She chose to continue her training at UOP Dental School as one of four residents in the Advanced Clinical Experience Residency, during which she completed advanced cosmetic cases, full mouth reconstruction training and provided instruction to dental students.
Dr. Johnston is committed to staying updated on current advances in dentistry. In addition to many continuing education courses, she is an ongoing member of the Partnership Study Group. Here, she meets with colleagues to discuss cases and participate in lectures with the goal of enhancing patient care.
In her free time Dr. Johnston enjoys spending time with her family, photography, and reading.
Gregory A. Hong, D.D.S.
Dr. Hong has been with the practice since 1987. He is a comprehensive general cosmetic dentist with advanced studies in the treatment of temporomandibular Joint (TMJ) disorders. He is a certified provider for the Invisalign orthodontic system. Dr. Hong is a 1981 graduate of the University of California, Berkeley, with a Bachelor of Science degree in Anatomy and Physiology. He is a graduate of the University of California, Los Angeles School of Dentistry, receiving his DDS degree in 1986.
Dr. Hong is a longstanding member of the American Dental Association, California Dental Association, Contra Costa Dental Society, 1987-present, and is a member of Partnership Dental Study Group. He is a past member of the Craniomandibular Institute and past founding member of the Academy of Computerized Dentistry. Dr. Hong was a contracted provider of TMJ treatment for Kaiser Permanente Medical Group 1989-2003.
Dr. Hong and his wife Rosellen have lived in Alamo for twenty years and have one adult daughter. He has held various volunteer coaching positions for girls' high school varsity softball at Las Lomas High school and San Ramon Valley high school, 2005-2012. He also coached Mustang Soccer Club 1996-2005 and girls softball, travel teams California Crossfire and the San Ramon Valley Girls Athletic league Valley Stompers 2003-2010.
Dr. Hong's hobbies include travel, fishing, golf, umpiring, and reading.