Meet Our Staff

Meet Our Staff, Your Dental Team

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Our relationship with you and your happiness with how you’re treated while under our care is vitally important to us because we realize you have a wide range of choices when it comes to selecting your dental professionals.

We have designed an environment that creates a balance between the science of modern dental care and a special place where you can feel comfortable and at ease. Our friendly, courteous staff welcomes you as a member of our family.

Our assistants and hygienists bring over 45 years of registered dental assisting and registered dental hygiene experience to their patient care.  Our administrative staff represent over 40 years experience in front office procedures.  Together, our team strives to surpass your expectations.

Click on staff names to learn more

Valerie Johnson Mastrovich, Practice Administrator / Business Manager


For more than 30 years, Valerie has shared her passion for health, team building and business administration to create an ever-improving environment of positive, comfortable support for Dr. Mastrovich’s patients and team. Her motto is simply, “The better we support and care about our team, the better we all support and care about our patients.” She strongly believes there is an invisible thread from our heart to those of our patients, and our job is to help them know we genuinely care about their well-being.

When she is not managing the business operations for the practice, Valerie keeps busy with her daughters, Morgan and Sydney. She also enjoys her morning “wake up” jog, glassblowing classes (to express her love of glass art), hiking, walking beaches, travel, and church choir.

“Twenty years from now you will be more disappointed by the things that you didn’t do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.” – Mark Twain

Debra Jenkins, Office Manager

dj-opDebra was drawn to the dental field because of her personal experiences as a dental patient and her desire to make a difference. She feels dentistry has continued to be her calling and passion for more than 30 years. She loves that every day is an opportunity to grow in the technical and the relationship aspects of the field. Debra enjoys sharing with patients all the compassion and wisdom she has learned from Dr. Mastrovich so they can make balanced and informed decisions.

When Debra is not spending time with her cherished grandsons or cheering on her sons at volleyball and basketball games, she loves hiking, mountain biking, collecting antiques, and muscle cars (her dream car is a ‘69 Chevelle SS 396).

“Do not go where the path may lead, go instead where there is no path and leave a trail.” – Ralph Waldo Emerson

Sheila Burger, Registered Dental Assistant

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Sheila is passionate about making each patient’s dental experience the best it can be. This passion has helped her bring her A Game each day, whether as an integral member of the Mastrovich Dental Team or volunteering in Mexico helping the underprivileged.

“Be joyful in hope, patient in affliction, faithful in prayer.” – Romans 12:12

Lori Philbin, Registered Dental Assistant, Expanded Functions


Lori decided to be a dental assistant during her sophomore year of high school. She joined the U.S. Navy, went to Dental Assisting School and worked for the military for 23 years. She lives in Escondido with her husband and furry pets. She is also a proud mother to daughter, Amelia, and her grandson. Lori is also passionate about sewing and handcrafting. She considers both dentistry and sewing to be her passions, and with dentistry, she is creating beautiful smiles that last a lifetime.

“We make a living by what we get, we make a life by what we give.” – Sir Winston Churchill

Liezel Hernandez, Registered Dental Hygienist


Liezel’s passion for dentistry began early in life and she pursued it in her native Philippines, becoming a dentist and practicing there before marrying her husband, Art, who she met in college and had moved to the US.  After moving to California, Liezel continued to work in dentistry as an assistant while evaluating her options, and chose dental hygiene as the best avenue of continuing to make a difference in high quality dental care. Liezel, Art and their son, Tristan, enjoy basketball, gardening and gathering with extended family.

“If you’re rejected, -ACCEPT     If you feel unloved,  -LET GO    If they choose someone or something over you, -MOVE ON    Remember that: In every NO from someone, is a YES to someone better…” Nick Vujicic

Kari Sumner, Registered Dental Hygienist


Kari’s dental career started in 1992 when she graduated from the dental hygiene school at Loma Linda University. She has worked with Dr. Mastrovich since 2006, and believes the passion he displays for his work and his patients has made her want to be a better dental hygienist. Kari loves helping her patients make their smiles the best they can be. She is married to an oral surgeon in the U.S. Navy and has two teen-aged daughters.

“Life is short, live it. Love is rare, grab it. Anger is bad, dump it. Fear is awful, face it. Memories are sweet, cherish them.” — Unknown