Meet the Team

Dr. Derek Clemmer grew up in Ripley, MS and graduated from Ole Miss in 2006. After graduating from University of Mississippi School of Dentistry in 2010 he spent some time at a community health center dental clinic. It was there he realized he wanted to focus his career treating the dental needs of children.

Dr. Clemmer is a member of the American Dental Association and Mississippi Dental Association. He opened the Happy Smiles Tupelo location in 2012 and is honored to serve families of Tupelo and the surrounding communities.

His favorite part of his job is being able to provide a child specific treatment and focused care to improve their health. At times, the parents have been to another office first and they were unable to complete the treatment their child needed.

Dr. Clemmer keeps busy with his wife and 3 children. They are active members of the New Albany First United Methodist Church.

Dr. Kristen Douglas  is a native of Mississippi’s sister state, Alabama, but has spent the last 16 years calling Mississippi her home. She received her BS from Mississippi College, and went on to graduate from the University of Mississippi Medical Center, School of Dentistry.

Before and during dental school, Dr. Kristen worked for a pediatric dentist and quickly realized how fun it was to work with children and their parents. In 2016, she completed a two-year pediatric dental residency at the University of Tennessee Health Science Center. While in residency, she had the unique opportunity to rotate through St. Jude and LeBonheur Children’s Hospitals as a part of her training.

Dr. Kristen is a Diplomate of the American Board of Pediatric Dentistry and is currently a member of the American Academy of Pediatric Dentistry, the Mississippi Dental Association, and the American Dental Association.

Outside of the clinic, Dr. Kristen makes her home with her husband and daughter. She would say that being a mother has greatly impacted how she practices. With so much information to process and decisions to make, she understands the challenges that parents face when it comes to making healthcare choices for their children. She considers it a privilege to be trusted with the care of your child.

Dr. Daniel Kirk Knighton is a native of New Albany, Mississippi. The decision to enter the world of dentistry was the result of shadowing a respected local dentist, the great Dr. Ronald Feather.

Dr. Knighton attended undergrad at the University of Mississippi in the graduating class of 2006, with a BS in Chemistry. He went on to attend dental school at the University of Tennessee, and from there, decided to dedicate his career serving children and we’re lucky to have him at Happy Smiles Tupelo.

Dr. Knighton is a dad and you can see that fun-loving and caring nature in the way he relates to the kids in his dental chair. He says kids dentistry is just a “fun work environment.” He likes seeing the kids he serves grow up, and can’t complain about having kids movies playing on the TVs all day.

He shares his life outside the clinic with his wife and two children.

Dr. Daniel Johnston was born and raised in Jackson, MS. Like many on our crew, he attended the University of Mississippi, receiving a BA in Physics in 2008. He had the goal of becoming a dentist, and went on to receive his DMD from the University of Mississippi Medical Center in 2013.

Dentistry always appealed to Dr. Johnston as a profession. His father is an Endodontist, and Dr. Johnston was able to see firsthand that he could have an enjoyable career dedicated to helping others and still have quality time to spend with his family.

Dr. Johnston's patients and their parents know him as being funny and easy to talk to. He's been known to talk shop on video games with the teens in the office, comparing notes on their favorite games.

After a busy day treating kids at the office, Dr. Johnston makes his home with his wife and two children.

Dr. Jerry Campbell is a caring and talented pediatric dentist, who possesses the highest qualifications and is extremely well liked by the patients and families he meets..

Dr. Campbell graduated college from the University of Mississippi and continued his studies at the University of Mississippi Medical Center where he received his Master of Science degree in Biomedical Sciences. He then attended the University of Tennessee College of Dentistry where he earned his Doctor of Dental Surgery degree with honors. While in Dental School, Dr. Campbell served as secretary of his dental fraternity, Xi Psi Phi, and was inducted into the Richard Doggett Dean and Marguerite Taylor Dean Honorary Odonatological Society, as well as the IMHOTEP Leadership Society.

He spent time volunteering for the American Student Dental Association (ASDA) Give Kids a Smile and the Remote Area Medical Clinic as a student doctor, as well as spending time with children at St. Jude’s Target House. After receiving his Doctor of Dental Surgery degree, Dr. Campbell completed his Advanced Education in Pediatric Dentistry at New York University Langone, a pediatric dental residency that offers extensive experience in all areas of the field including comprehensive preventative and therapeutic oral health care for infants and children through adolescence, including those with special health care needs.

As a child, Dr. Campbell’s own pediatric dentist made an impression on his life and career path. As he grew older and saw his younger brother attend the same dentist, he truly noticed the extra effort that each team member put in to make every experience enjoyable for all children. Dr. Campbell decided he wanted to pursue a path that included working with children to hopefully be a positive influence on the children and leaders of our future..

After many years of training, Dr. Campbell is excited to continue his journey with our team at Happy Smiles. He looks forward to staying on the cutting edge of pediatric dentistry through continuing education.

Dr. Preston McAlexander grew up in Holly Springs, MS and attended the University of Mississippi where he received his undergraduate degree in 1999. He continued his studies at the University of Mississippi Medical Center and was awarded the Doctor of Dental Medicine degree in 2004. While at the School of Dentistry, he served as student body president and representative to the American Dental Association.

Dr. McAlexander worked for five years in a community health center dental clinic as part of the National Health Service Corps. He is a member of the Mississippi Dental Association and the American Dental Association.

At the health center dental clinic, Dr. McAlexander was able to see first-hand the impact that quality dental services can have on a family. He is proud to continue his work to bring great dental care to all children, regardless of their family income.

Dr. McAlexander enjoys life outside the office with his wife and two kids. He is an active member of his local United Methodist Church.

Dr. Jason Leach was born and raised in Jackson, MS. He is proud of his Alma Mater, Ole’ Miss, having earned both his undergraduate degree and his Doctor of Dental Medicine from the University of Mississippi.

Dr. Leach believes in providing the children he serves with the very same treatment he would want his own kids to receive. By all the smiling faces in his dental chair, we think he is succeeding!

A leading dentist in our mobile dentistry outreach program, Dr. Leach is passionate about helping families access critical preventative services for their children. This program partners with our local schools and Head Starts to help improve health outcomes for the children they support.

In the mobile program and at the office, Dr. Leach encourages healthy habits that will prevent tooth decay in Mississippi children.

Dr. Leach spends his spare time with his wife and two kids. What could be better than that?