Meet The Team

Our Doctors


Dr. Robert F. Morrison
CEO and Clinical Director

Dr. Morrison is the owner and founder of Robert F. Morrison, DMD, PC, a General Williamsburg Dentist Practice for children and adults since 1992. Dr. Morrison founded the practice after returning from being stationed with the U.S. Navy in England with the goal of providing genuine and compassionate care for the families of Williamsburg and the greater Hampton-Roads area. The practice has grown to incorporate some of the latest dental technologies as well as continue to provide extensive and patient-oriented care for families and individuals. With a great team of Williamsburg dentists and staff, the offices of Morrison Dental Group pride themselves on the personal attention and skill that they can offer their patients.

Dr. Morrison graduated from Southern Illinois University with a Bachelor of Science degree in Chemistry in 1979. He attended Southern Illinois University School of Dental Medicine, graduating in 1982, completing a post-doctoral residency in Comprehensive Dentistry. He served as a dental officer ashore and afloat from 1982-1991 in the U.S. Navy and was the dentistry department head afloat the U.S.S. Guam. Dr. Morrison was head of the Pediatric Department from 1987-1988, Dental Clinic, Norfolk Naval Station, Norfolk, Virginia.

Dr. Morrison is married to Alison, who serves as Morrison Dental Group’s CFO. They have two sons: Frank, a LCDR in the United States Coast Guard and Alex, who also works with Morrison Dental Group as the Chief Compliance Officer. In his spare time, Dr. Morrison is a dedicated family man and enjoys fishing on the Chesapeake Bay, as well as kayaking and restoring British MG cars.

Dr. Morrison is a member of the ADA, VDA, and AADSM.



Dr. Ralph Zentgraf

Dr. Ralph Zentgraf was born in Toronto, Canada, but grew up in California and Utah. He attended Weber State University in Utah for his undergrad degree and the Medical College of Virginia at VCU for dental school. He has volunteered for the medical examiner’s office and spent some time out of the country in the Philippines and in Guatemala doing dental service.

From the age of five, Dr. Zentgraf knew he wanted to be a dentist. He loved his own family dentist and knew he wanted to work in a field that helped people. His favorite part of dentistry is oral surgery because he gets to help people walk out of the office feeling instantly better. Dr. Zentgraf and his wife, Rochelle, have four children and one grandchild. In his spare time, you can find him golfing, traveling and skiing. He describes himself as someone who is low key but detail-oriented, and who doesn’t take himself too seriously. A fun fact about Dr. Zentgraf is that his first language is German.


Dr. Katrina Thatch

Dr. Katrina Thatch has always had a passion for science and art, so when she first shadowed a dentist in high school, she became excited to find that dentistry so seamlessly intertwines these two fields together. She spent many hours shadowing in offices and free clinics and witnessed the incredible impact that dentistry can have on the lives of patients. The bonds that dentists form with their patients is what drove her to pursue this field and attend dental school.

Dr. Thatch was born in Virginia, but has lived in Colorado, Minnesota, North Carolina, and Maryland. She is happy to come full-circle and return back to Virginia. She attended the University of North Carolina – Chapel Hill for her undergraduate degree and then went on to attend the University of Maryland School of Dentistry, graduating Magna cum Laude. She completed a one-year residency in general dentistry at VCU’s School of Dentistry as well. Dr. Thatch is a member of the ADA, VDA, Richmond Dental Society, and American Association of Women Dentists. She has volunteered in numerous free clinics across Virginia, Maryland, and North Carolina and plans to become more involved in volunteer opportunities – such as Smiles for Heroes and Give Kids a Smile – with Morrison Dental Group.

Dr. Thatch most enjoys being able to bring a new, beautiful smile to the faces of her patients. She loves educating, comforting, and instilling confidence in her patients as well. She is married to Justin, a civil litigation attorney, and they have a 19-pound British shorthair cat named Karl. She enjoys reading, cooking, painting, and watching college basketball. She and her husband both love exploring Virginia on weekends and visiting the beach. Dr. Thatch describes herself as compassionate, energetic, a good listener, a lifelong learner, motivated, and dedicated. She is a member of a book club and plans to become more involved in her local church. Dr. Thatch loves to travel, having studied in Florence, Italy during her time in college. A fun fact is that she has played several interesting musical instruments throughout her life including the oboe, flute, piano, and xylophone.



Dr. Chriska Mustafa

Dr. Chriska Mustafa was originally born in Kurdistan, but moved to Centreville, Virginia when she was eight. She attended VCU for her undergraduate degree where she majored in Biology and minored in Chemistry and Business. She then went on to attend Howard University College of Dentistry where she earned her D.D.S. Dr. Mustafa has spent time volunteering for Mission of Mercy, Hope for the Homeless, Free Clinic of Northern Virginia, and many more.

At the age of 15, Dr. Mustafa shadowed at a dental office for a school assignment and fell in love with the field. She continued shadowing just for fun and was hired as a front desk administrator when she turned 16. She was given more and more responsibility within the dental office and by the end of high school she was working as a dental assistant. She loves the dental field because she enjoys being a health care provider while also being a friend to her patients. She appreciates building lasting relationships with patients and their families and the community around her, as well as meeting patients from all walks of life.

Dr. Mustafa describes herself as loyal, compassionate, and hard-working. She is married to Dr. Matthew Gaynier who works in our Chamberlayne office. In her spare time, you can find Dr. Mustafa going to concerts, sporting events, and travelling. Her next goal in life is to get her pilot’s license. Although she has her D.D.S., her favorite title is “Aunt.”

Dr. Mustafa is a member of the VDA, ADA, DC Dental Society, and the Academy of General Dentistry.


Our Staff

Amanda Hewitt, Area Manager

Amanda Hewitt joined the MDG family in July of 2018. She was born in Cape May, NJ and was raised in New Gretna, NJ. After going to school for Forensic Science, her life took a different course and brought her here to Virginia and to our office. Amanda most enjoys working with our patients. She gets satisfaction from seeing someone walk in the door upset and hopeless because they’re in pain or just don’t like their smile, and they leave happy, healthy, and smiling! In her spare time, Amanda enjoys hunting, fishing, crabbing, and spending time with her kids. She has a cat, dog, and a very old goldfish. A fun fact about Amanda is that she is a sharpshooter.

Alex Morrison, Regional Manager

Bio coming soon.