Brea Ranch Dentistry
Johnny Koo, DDS:
Practice Profile Page


Brea Ranch Dentistry
Johnny Koo, DDS
Brea, CA













A list of major dental treatments which I offer my patients:

Dental cleaning

White fillings


Inlays & onlays


Pediatric dental care


Clear aligners

Porcelain veneers

Teeth whitening

Dentures & partials

Root canal treatment

Tooth extraction

TMJ treatment

Dental implants


Offers Even28 at-home™? No

Offers Even28 at-dentist™? No

Offers Invisalign®? Yes


Monday: 9:00 am to 5:00 pm

Tuesday: 9:30 am to 6:00 pm

Wednesday: Closed

Thursday: 9:00 am to 5:00 pm

Friday: 9:00 am to 4:00 pm

Saturday: Closed

Sunday: Closed





Check out what some of our happy patients are saying about us:

Lisa M. from Commerce, CA (Source: Yelp)


Let me say that I only visited the dentist out of pure necessity. (…) I only decided to go after weeks of pain from my wisdom tooth. Even at my age, I still had anxiety going in! The staff was understanding and did everything to make me comfortable and relaxed. Dr. Johnny Koo took his time explaining what he was going to do and made sure that I was calm and ready to have my wisdom tooth removed. As I lied back, eyes closed and listening to my tunes, I was totally relaxed. Before I knew it Dr. Koo tapped me on the shoulder to let me know it was all done. My experience was great!
I highly recommend Brea Ranch Dentistry. Everyone had a smile, and the professional quality was excellent. Love that it was quick and painless. Great doctors, super great staff!!

Greg Cahill (Source: Google)


Phenomenal dentist office! I went in for a couple of cavities, and can’t say enough good things about my experience. The staff was warm, friendly, and super easy to talk to. The doctor was really personable and explained what he was doing throughout the entire process. If all dentists operated like these guys there wouldn’t be such fear of dentists. 10/10 would recommend.

Daniel P. from Anaheim, CA (Source: Yelp)


I just moved to Orange County 2.5 years ago and finding a new Dentist is NEVER fun or easy. But after my visit here I won’t have to say that EVER again. Dr. Koo and his entire staff are amazing!! My first impression of the office and staff were important, I felt welcomed, comfortable, and the staff were extremely professional and kind. I always have a lot of questions and Dr. Koo explained everything and didn’t make me feel pressured into doing treatments I didn’t honestly think I needed. He was very thorough yet conservative. I highly recommend Dr. Koo!!

Cheryl J. from Brea, CA (Source: Yelp)


Thank you Dr. Johnny Koo…you are the very best there is out there.  Every time I go to this dentist it’s a wonderful experience.  If I’m apprehensive prior to my appointment, believe me, by the time I just sit in his chair, it all disappears.  He is so professional and calm…I love this dentist…oh by the way, he does beautiful work also!

Josh O. from Anaheim, CA (Source: Yelp)


Came here to get 3 wisdom teeth extracted. They were very professional and respectful. The removal process was near painless. I had one tooth removed at a different dentist a year ago and feared the aftermath. But after Brea Ranch removed all 3 my mouth healed less than a week. Would recommend this place to everyone.

Kristin M. from Irvine, CA (Source: Yelp)


Brea Ranch Dentistry definitely met my expectations and even exceeded them, for myself and my family. It is hard to find a new Dentist to trust after being with the same one for more than a decade, but Dr. Johnny and Dr. Karen made us feel like we had been their patients forever. They addressed any concerns we had and we walked away having made our 6 month check-up appointments. Susan and the rest of the staff are great too. It’s like going in and catching up with old friends. I definitely recommend Brea Ranch Dentistry!

Melissa C. from Diamond Bar, CA (Source: Yelp)


I have been using Brea Ranch Dentistry for a few years now and have never been disappointed. The office staff along with the doctors are exceptional. Always kind, efficient and professional. I highly recommend them and will continue seeing them for my dental needs!

KD. J. from Garden Grove, CA (Source: Yelp)


My son and I both go here and love it!  Both (partner doctor) and Dr. Johnny are professional, friendly and patient as is everyone that works here.  Going to the dentist is never fun, but coming here is the most pleasant dental experience I’ve ever had.

Jennifer Young (Source: Facebook)


I am so afraid of the dentist, and it’s been a while since I’ve had a checkup and cleaning! I researched dentists in Brea and decided on Brea Ranch. I was nervous but I went. I’m so glad I did!!! I adored the staff! I loved the dentist! I loved that it’s in Brea! I didn’t feel a thing and the dentist was very thorough. My husband has an appointment coming up as well. I’m just so relieved.

May M. from New York, NY (Source: Yelp)


My husband and I were treated by Dr. Johnny Koo and we had a very smooth experience.  I was scheduled for the very last appointment of the day and was 15 minutes late (so sorry!). They were willing to stay 30 minutes after closing to make sure I had a very thorough cleaning. I really appreciated that.  Very friendly staff from reception, dental assistant, and Dr. Johnny Koo. We will definitely be back for our 6-month cleanings!

Lori J. from Yorba Linda, CA (Source: Yelp)


Thank you, Dr. Karen Koo and Dr.  Johnny Koo for the great experience and quality work you have done on my teeth. I am usually VERY apprehensive about needles and it was no sweat at all. In fact, I have let go of my childhood fear ( the moment of numbing ).  Your assistant, staff and front desk people are considerate, caring and great professionals. Especially Susan 🙂 she is caring, understanding, and extremely helpful scheduling and answering all my questions regarding payments, procedures, and making me feel welcome.
Thanks to your gentle touch and your professional, yet personable, service. I am enjoying my new smile!

Larry H. from Laguna Woods, CA (Source: Yelp)


We made an appointment for my wife Susan. They got her in the very next morning. She was in a lot of pain and had been for about three months. Susan got her set up with the paperwork and was very helpful. My wife was very nervous going into this because she had a couple of bad experiences with dental work in the past. She had to have two molars removed. She didn’t even feel the injection to numb her mouth to do the procedure. Dr. Koo is the greatest. The treatment Susan received from Dr Koo was off the charts. Her experience at his office totally changed her mind about dentists. So, that being said if you have any reservations about getting dental work done Dr. Koo will change your mind. Painless and easy to talk to and explains everything very well. His office gets an A++.

Miki Ewens (Source: Google)


Highly recommended dental office where they take excellent care of all dental issues, are very conscientious about explaining everything that needs to be done, and are extremely trusting on costs charged. We drive over 60 miles one way to this office because of their high integrity. It is really difficult to find an office so trusting and caring about your dental health.

Rodrigo G. from Duarte, CA (Source: Yelp)


So happy my wife and I found such a great dentist so near our apartment. They treat their patients like family and we definitely don’t see us going anywhere else. Fantastic practice!

Alex K. from Milpitas, CA (Source: Yelp)


I’ve had so much dental work done and I can honestly say my experience at Brea Ranch Dentistry was the best in my life! Drs. Johnny Koo and (partner dentist) are so awesome! First of all Dr Johnny Koo gave me my first ever “comfortable anesthesia shot. Seriously, no pain!!! I actually didn’t feel it. And then he proceeded to EXTRACT some teeth all of which I also felt no pain whatsoever, and, I’m not known as a  “tough guy”—ie. My last visit to the I almost cried (…).

Monica M. from Claremont, CA (Source: Yelp)


The best experience I’ve ever had in a dental office. The staff were amazing and so helpful. The doctor was wonderful! I definitely will recommend to everyone in need of a dentist. Call them and speak with Susan, she will take good care of you!

Michelle J. from Brea, CA (Source: Yelp)


I am so afraid of the dentist, and it’s been a while since I’ve had a checkup and cleaning! I researched dentists in Brea and decided on Brea Ranch. I was nervous but I went. I’m so glad I did!!! I adored the staff! I loved the dentist! I loved that it’s in Brea! I didn’t feel a thing and the dentist was very thorough. My husband has an appointment coming up as well. I’m just so relieved.

Jane W. from Orange County, CA (Source: Yelp)


I came here specifically for the Zoom! whitening treatment and am so I glad I finally did it. Years of coffee and soda had turned my teeth yellow and gross, but after Marissa worked her magic, they came out dazzlingly white! She paid incredible attention to detail and did everything with a gentle touch. Love my new smile! Thank you, Marissa and Brea Ranch Dentistry!

Claudia J. from Lakewood, CA (Source: Yelp)


Every time I enter this office, I am greeted with a smile!  I am escorted right back to see the Dentist, so they’re respectful of my time!  They’re very caring, patient and professional!  I highly recommend this office.

Gina L. from Riverside, CA (Source: Yelp)


If you looking for a dental office for yourself and your family look no further. Dr Koo is simply the best dentist in town. Not only is he an exceptional dentist, he is a down to earth honest dentist. He explains your treatment in detail and takes his time. I finally found an office to refer all my family and friends to. You will not be disappointed!

Rosemary R. from Lake Forest, CA (Source: Yelp)


Dr. Koo and his entire staff have ALWAYS provided me with the utmost professional, quality care. After going to a number of dentists in the area for myself and my father, I have found “my home” with this wonderful team. 10 stars!


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.