Our Team

Mercedes Leoncio, DDS
University of the Pacific Arthur A. Dugoni School of Dentistry

Dr. Mercedes Leoncio was born and raised in the Bay Area.  She attended college at the University of the Pacific Stockton campus in the advanced pre-dental program.  During her time at Pacific, Dr. Leoncio served as President of the tri-Beta, the National Biological Honors Society and earned her Bachelor of Sciences degree, graduating Cum Laude.  She then went on to the University of the Pacific School of Dentistry where she earned her Doctorate of Dental Surgery. During her time at the Dental School, she served as President of the Delta Sigma Delta Fraternity.  She is currently a member of the American Dental Association, California Dental Association, Southern Alameda County Dental Society, California Center for Advanced Dental Studies and the American Academy of Clear Aligners.  Dr. Leoncio loves working on children and has a passion for her Invisalign cases as a Gold-Plus tier Invisalign provider. She enjoys serving at the the Union City Pacific Clinic in their annual “Give Kids a Smile” event.   In her free time, Dr. Leoncio enjoys playing volleyball, tennis, cooking, spending quality time with her family and going to sporting events (Go Niners, Go Dubs, Go A’s!!).



Doreal Onea DDS, MS
Board Certified Periodontist

Dr. Onea received his Doctor of Dental Surgery degree from the University of Pacific San Francisco, and completed a three year post-doctoral periodontal program at the University of Oklahoma Health Sciences Center, where he received a Master of Sciences degree in Periodontics. His educational background also includes pre-doctoral studies completed at California State University, Hayward, where he received a Bachelor of Science degree in General Biology, and prior to that a Biology teaching degree from the College of Baia Mare, Romania.

He is a member of the Alpha Epsylon Lambda Honor Society , American Academy of Periodontology, California Periodontal Society, American Dental Association, California Dental Association and Sacramento Dental Society.

Dr. Onea’s knowledge and experience in the field of Periodontics were tested and endorsed by the American Board of Periodontology of which he is a diplomate – a significant accomplishment for a periodontist. He has Advanced Cardiac Life Support certification, he is a provider of Continuing Education courses for dentists, and a California state inspector for IV sedation certifications.

His active lifestyle and hobbies include dentistry and its gadgets, nature photography, skiing, kayaking, motorcycles and traveling .

Amun Rattan, DDS
University of the Pacific Arthur A. Dugoni School of Dentistry

Dr. Amun Rattan is a lifelong resident of the Bay Area who studied at University of the Pacific for his advanced general dentistry residency, Doctorate of Dental Surgery, and Bachelor’s degree in Biology. He is a current member of the American Dental Association, California Dental Association and the Southern Alameda County Dental Society. Dr. Rattan is known for patiently educating his patients with anything from tips to care for their oral health at home to detailed discussions of the risks and benefits of same-day treatment options, and he says that his favorite thing about dentistry is building long term relationships with his patients based on compassion and mutual trust. Outside of the office, Dr. Rattan can often be found cooking or baking, making music, watching movies and relaxing with family. 

Iliana Nguyen, DDS
UCLA School of Dentistry.

Dr. Nguyen is a Bay Area native who grew up in Cupertino and graduated cum laude from UC San Diego with a bachelor’s degree in Biochemistry and Cell Biology. Loving her time and the weather in Southern California, she went on to receive her DDS from UCLA School of Dentistry. Dr. Nguyen then embarked on an adventure and moved to New York City to complete a rigorous General Practice Residency at Lincoln Hospital in South Bronx where she gained further exposure to all aspects of dentistry and fell in love with the Big Apple. Dr. Nguyen’s favorite part of being a dentist is getting to meet new patients and developing the patient dentist relationship. She is a member of the Santa Clara Dental Society, California Dental Association and American Dental Association. In her free time Dr. Nguyen loves being active, hiking, trying out new restaurants and spending time with family and friends. Dr. Nguyen has a sweet tooth and loves baking and drinking boba. 

Michelle Vaughn, RDH
Registered Dental Hygienist

Originally born and raised in Brooklyn, New York, Michelle has always had a love for the dental field since childhood. As an adult, she pursued her dental dreams by attending Chabot College in Hayward, California, where she received her degree in Dental Hygiene, graduating with Honors. She is also a current member of the California Dental Hygienists Association. Michelle is driven to educate her patients on the link between oral health and systemic health.  She loves finding creative ways to get her patients engaged and excited about improving their oral hygiene habits at home. In her free time, Michelle loves to sing at church and spend time with family and friends. 


Wendy Pluth, RDH
Registered Dental Hygienist

Wendy has been practicing in the dental field since 2002. She became a Registered Dental Assistant in 2006 and decided to get her bachelor’s degree in 2011. She has always wanted to become a Registered Dental Hygienist and graduated in a dental hygiene program in 2017. Wendy has a passion for educating each patient on oral hygiene so they achieve a healthy smile.

Rowena Zamora
Treatment and Financial Coordinator

Rowena has been working as a Financial Coordinator in medical/dental offices for more than 14 years and she loves her job. She was Medical Receptionist for more than 14 yrs, a medical biller for 12 yrs and a Dental biller (NUVO Dental) since 2014. Her motto: Smile & the world smiles with you =)

Herman Kaur
Dental Assistant

Herman Sandhu was born in India and has been living in the Bay Area since 2018. She has been a Dental Assistant for 3 years and is working towards becoming a Registered dental hygienist. Her passion is to educate people about dental hygiene and oral health. She loves to interact with her patients and listens to them patiently while guiding them how to achieve their dental health goals. In her free time she enjoys watching sports, movies, playing fun board games, going for a walk with her husband and enjoy nature. She is a big fan of Golden state Warriors. Let’s Go Warriors!!!