Dr. Johnny began his path to dentistry by earning a degree in psychobiology, then continuing on with his four-year dental training at Loma Linda University School of Dentistry. As the associate dentist for a group practice, he has devoted the last decade to furthering his dental continuing education and advancing his clinical skills. He and his wife Karen have been serving the local community since the Summer of 2012 when they became the new owners of Brea Ranch Dentistry.

Dedicated to the pursuit of advanced training, Dr. Koo works to stay abreast of the latest techniques and technologies in dentistry. He has continued to pursue advanced education in areas important to his patients, such as cosmetic and implant dentistry.

Dr. Koo is passionate about helping his patients achieve excellent oral health and creating a quality patient experience. From offering alternative treatment options to helping each patient come to a decision they are comfortable with, his desire is for his patients to be happy with the treatment they receive.

In his spare time, Johnny enjoys an occasional round of golf or tennis and spending time with his family. His greatest joys are his 8 and 10 year old daughters, who have a blast playing games and outdoor activities with their hands-on dad. He is happily married to his best friend and fellow colleague Karen.

Opening Hours


9:00 am - 5:00 pm


10:00 am - 6:00 pm




9:00 am - 5:00 pm


9:00 am - 5:00 pm






Our Address:

936 E Imperial Hwy Brea, CA 92821


33.912717071321, -117.89157284512191