Our Medical Team & Oral Surgeons

Oral Surgeon, Thomas H. Simpson, DMD, MD

Dr. Tom Simpson is a board certified oral and maxillofacial surgeon who joined The Center for Oral & Maxillofacial Surgery in 1991. After completing his bachelors degree in chemistry at that university of North Carolina Chapel Hill, he was commissioned as an officer in the United States Marine Corps. He spent five years serving as an artillery officer in Hawaii and abroad, then returned to school to pursue a career in oral and maxillofacial surgery. He earned his Doctor of Dental Medicine in 1986 at the medical University of South Carolina Charleston, finishing first in his class. He earned his Doctor of Medicine and completed his oral and maxillofacial surgery residency in 1991 at the University of Alabama Birmingham. He is a diplomat of the American Board of Oral and Maxillofacial Surgery and the National Dental Board of Anesthesia. Dr. Simpson is a past Chief of Medical Staff at Piedmont Medical Center and remains active in medical staff leadership. He has an active member of First Associate Reformed Presbyterian Church and is an avid scuba diver and skier.

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Marjorie J. Risser, DMD

Dr. Marjorie J Risser has been practicing in Rock Hill for over 20 years since she completed her residency at the medical College of Virginia in Richmond. Prior to residency, she completed a year of general practice residency at the Hospital of the University of Pennsylvania. She earned her Doctor of Dental Medicine degree from the University of Pennsylvania School of Dental Medicine and has a bachelor of science degree from Juniata College in Pennsylvania. When she joined at the practice in 1996, she was the first female oral and maxillofacial surgeon in South Carolina.


Dr. Risser is a Diplomate of the American Board of Oral and Maxillofacial Surgery and the National Dental Board of Anesthesiology. She is a fellow of the American Association of Oral and Maxillofacial Surgeons in the American Dental Society of Anesthesiology, and is a member of the American Cleft Palette, Craniofacial Association, Health Volunteers Overseas, and local and state dental and oral surgery associations.


She was born and raised in Lancaster County, Pennsylvania (Amish country), but now calls Rock Hill home. She is married and has two teenage daughters who attend Westminster Catawba Christian school. Dr. Risser enjoys traveling, creating photo books, reading, and playing with her dog. On Sunday mornings and Wednesday nights she can often be found singing with the praise band at Mount Gallant Church of God where she attends regularly. 

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Mark T. Billman, DMD, MD

Dr. Mark T. Billman is a graduate of the University of Pittsburgh, School of Dental Medicine and the Medical College of Pennsylvania where he received his dental and medical doctorate degrees. He completed two years of general surgery at Allegheny General Hospital in Pittsburgh, Pennsylvania. He received his training in oral and maxillofacial surgery and advanced training in facial plastic surgery also at Allegheny General Hospital.


Dr. Billman is an Assistant Professor of Surgery at Edward Via College of Osteopathic Medicine and is active in the education of medical students. He has served as the Chairman of the Department of Surgery, Chief of Staff, Chairman of the Investigational Review Board, and Chairman of the Board of Governors at Piedmont Medical Center in Rock Hill, South Carolina. He is currently on the Board of Governors at Piedmont Medical Center.


Dr. Billman is a Diplomate of the American Board of Oral and Maxillofacial Surgery and  the National Dental Board of Anesthesiology. He is also a member of the American Association of Oral and Maxillofacial Surgeons, the American College of Oral and Maxillofacial Surgery, and American Dental Assocation

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Rhonda G. Carter, DDS

Dr. Rhonda G. Carter is a graduate of the Medical College of Virginia School of Dentistry. She completed her residency in general practice at The University of Texas/Audie Murphy Veteran’s Hospital in San Antonio, Texas. She received her training in oral and maxillofacial surgery at the Washington Hospital Center in Washington, DC. Dr.  Carter is certified by The American Board of Oral and Maxillofacial Surgery and is a Fellow of The American Association of Oral and Maxillofacial Surgeons. She is also a Fellow of The American Dental Society of Anesthesiology and a Diplomate of The National Dental Board of Anesthesiology. Dr. Carter has an intense interest in dental implants and is a member of The Academy of Osseointegration.


Originally from Virginia, Dr. Carter joined the practice in 2004 and enjoys being an active part of the community. She has participated locally with The Dental Access Day and has traveled to Jamaica to provide surgery for that community. She currently offers her service to nonprofit clinics.


Dr. Carter lives with her husband Ken on Lake Wylie where they enjoy spending time on their boat. You will likely find her playing golf on the weekends. Her other interests include traveling and cooking gourmet food.

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Maria Magnolia

Maria Magnolia has been the clinical coordinator at The Center For Oral & Maxillofacial Surgery, PC for the past 20 years.  Prior to that she worked as a chairside oral surgery assistant during which time she obtained certification through the DAANCE program (Dental Anesthesia Assisting National Certification Examination).


In 1984 she received her training by working chairside with Dr. Christopher Proto in Babylon, NY. She studied and challenged the DANB exam in 1985 and has been a National Board Certified Dental Assistant since then. Maria utilized her dental knowledge to obtain a business affiliation with Henry Schein Dental, Inc.  After one year of success in sales she was promoted and was given the title of Dental Technical Information Specialist. It was while in that position that Maria’s husband Harry was offered a management position in Rock Hill and the family relocated there in 1990.


Maria enjoys baking and cooking large meals for her family’s events and holidays. She is the proud mother of three sons, grandmother of seven, and great-grandmother of three. After work, you can find her swimming, walking or doing Yoga for relaxation. 

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Caroline Rock

Caroline Rock was born and raised in Rock Hill and is a graduate of York Technical College Dental Assisting Program. After graduation, in 1991, she was hired by The Center of Oral & Maxillofacial and enjoyed working here until she moved to Charleston in 1994. While in Charleston, she worked as an oral surgery assistant and later as a chair side assistant for Dr. Betsy Davis, an oral and maxillofacial prosthodontist for MUSC.


In 2001, Caroline moved back to Rock Hill as a mother of two boys and was rehired at The Center for Oral & Maxillofacial Surgery as a fill-in assistant while also a stay at home mother. In 2010, she was hired part time and later full time as the assistant to the Clinical Coordinator.


Outside of her work at The Center, Caroline enjoys being with her two sons, playing with her dogs, and woring on projects around the house.

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Shirletta Lewis

Shirletta Lewis has been the Office Administrator at The Center for Oral & Maxillofacial Surgery since August 2018. Prior to this position, she acted as the Administrative Assistant in the insurance/claims department since joining the practice in 2003. Shirletta received her Bachelors of Science degree in 2002 from Winthrop University.


Shirletta was born and raised in Hemingway, South Carolina. She is married and has two daughters. When not at The Center, she enjoys traveling and spending time with family and friends.

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The Center for Oral & Maxillofacial Surgery

Fort Mill, SC (803) 802-7700 Rock Hill, SC (803) 324-1160 Lancaster, SC (803) 285-9492

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