Meet Our Team

Call (909) 989-6661




Mrs. Diana Keen

Front Office



Hello, my name is Diana Keen, wife of twenty-eight years to Dr. C. Mark Keen. We have two boys together, Dr. Bryce M. Keen and soon to be Dr. Blake C. Keen who is still at USC Dental School. I grew up in Hacienda Heights, CA and have two sisters and a brother. Because our last names began with "K", Dr. Keen and I were in the same homeroom together in High School. I didn't get to know him until we both worked for Sears. I was a hardware manager at Sears for 18 years, and Dr. Keen's father was my boss. Dr. Keen was given a summer job at Sears before he started Dental School. This is when we were reunited. It is amazing how things work out. I enjoy outdoor activities such as camping, hiking, boating and my favorite, motorcycle riding! I began working for Dr. Keen when he first started his office in 1995, but only until he was able to hire a Receptionist, and now I am back in the office during these difficult COVID times. It is great working and helping all of the wonderful patients we have at the office. The best part of my new work day is coming home to my two excited Dobermans, Prince and Roxy, that miss me and don't know why I have left them all day.



Monique Est. 2016

Office Manager


 Hi! My name is Monique and I am the Office Manager at Keen Family Dentistry. I have worked with Dr. Keen since May 2016; however, I have been in the Oral Surgery and Dental field since 2015. Dentistry is truly my passion. I absolutely love our patients and the relationships we establish with them. My goal is to provide you with the best care, answer all of your dental questions and assist you in the best treatment to having a gorgeous smile. When I’m not at the office I enjoy spending my days surrounded by my family and going on different adventures with my pup, Cooper! Working with Dr. Keen and the rest of our staff is the best experience and we truly are one big family that I am so grateful to be a part of! 

Zuleyka Est. 2023

Treatment Coordinator



Hello! My name is Zuleyka, I also go by Zee, Zuley, or Zules. I have been in the Dental industry since 2022. I am a certified Interpreter in the community and educational field with knowledge of legal and medical terminology to interpret. I love meeting new people, being able to help others, and connect with others on a personal level. In my spare time I enjoy spending time with my boyfriend, who is my high school sweetheart, and my younger siblings. I look forwarding to meeting all our existing patients as well as all the new ones!

Madison Est. 2023

Dental Assistant


Hi! My name is Madison, but you can call me Maddie. I recently moved back to California after living in Colorado for 18 years and it feels so good to be back in California! I live in the Rancho Cucamonga area with my mom, sister, niece and nephew. I have a passion for dentistry and providing education, love and care to every patient I see. When I'm not at work, you can find me at Disneyland on the Jungle cruise, Universal Studios on the Mummy ride or Knotts on the Water Rapids. I look forward to seeing all of you!

Eric Est. 2023

Dental Assistant



Hi I'm Eric! I'm Keen Family Dentistry's newest Dental Assistant. I wanted to introduce myself to everyone! I am very excited to meet everyone. A few things about me is that I enjoy camping, hiking, off-roading, and music!

Jazzmin Est. 2019

Registered Dental Hygienist


Hello, my name is Jazzmin! I have grown up in the Upland area since the age of 10. Back in 2015, I received my Bachelors of Science in Dental Hygiene from West Coast University. I always strive to ensure all of my patients feel 100% comfortable in our office. Away from the office, I love spending time with my husband and beautiful children, Aria and Ashton. One of my favorite things to do on a Friday night is to play board games with my family!

Stephanie Est. 2022

Registered Dental Hygienist



Hi, my name is Stephanie! I grew up in Alta Loma and went to Alta Loma High School. I graduated from San Joaquin Valley College and received my degree is Dental Hygiene in 2009. My goal is to keep my patients happy, comfortable, and coming back! In my free time, I enjoy hiking and camping with my family and our two dogs. My favorite thing to do is watch my kids play their sport. My son, Dylan, plays baseball at Etiwanda High School and my daughter, Charlie, plays volleyball at Froza1. I'm so excited to be a part of this office and can't wait to meet you all!


We combine experience with the latest in dental technology to deliver the best patient experience possible.



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