Meet the Doctors - Amazing Smiles
Meet Dr. Jeff Mastroianni

Jeff is passionate about life and breathes fun and excitement into everything he does. Whether that’s coaching his daughter’s soccer team, or motivating and inspiring his orthodontic team on a Monday morning; Jeff is always fully committed to whatever endeavors he takes on. It could be straightening teeth at the office, or being a leader in the community, but it’s always done with a drive and passion to help others be their best.

Dr. Jeff feels privileged and blessed every single day to be a member of this great profession! Beautiful smiles build confidence in so many ways and he feels strongly about the lasting value of orthodontic treatment.

Dr. Mastroianni and family

Family Life

At the heart of everything Jeff does is his family! There is no doubt about the passion he has for spending time with Julie, his wife of 20 years, as well as their amazing daughters Anna (16), and Nikki (13). When he’s not straightening incisors, Jeff really enjoys relaxing trips to the beach, amazing dinners out with his lovely wife, and attending the countless activities and sports his daughters are involved in!

In The Community

Having donated well over 1 MILLION DOLLARS to schools, civic organizations, sports teams, churches, pageants, and many other charities, he’s proven nobody takes service to the community more seriously! He also helps families in need, whether they’ve had the misfortune of a fire in their home, or loss of a parent. He’s always there to lend a hand. Dr. Jeff believes in giving back to the communities and families that have placed their trust in his hands.


  • University of Missouri-Columbia

  • Southern Illinois University School of Dental Medicine

  • St. Louis University Center for Advanced Dental Education (orthodontics)

Continuing Education

Because he believes in importance of giving his patients the best care possible, Dr. Jeff dedicates a great deal of time to continuing education classes and seminars. Jeff is a member of several prestigious orthodontic organizations such as:

  • The Roth-Williams Society

  • The Progressive Orthodontist Study Club

  • The Schulman Study Group

  • American Board Orthodontics (board-certified)

  • American Association of Orthodontists

  • Midwest Society of Orthodontists
Meet Dr. Julie McCray

Dr. McCray grew up in Iowa and has wanted to be an orthodontist since she was a patient of the University of Iowa orthodontics department as a middle schooler.


She attended the University Of Iowa as an undergrad with a major in Biomedical Engineering while working as a research assistant in the orthodontic department.

For dental school, Dr. McCray attended the University of Nebraska and followed it up with the orthodontic program at St. Louis University.

Known for her calm, compassionate chairside manner and individualized approach, Dr. McCray loves being able to meet and get to know her patients during the orthodontic process.

Family Life

Dr. McCray and her husband have raised their four children in the area, and love discovering new things to do together, along with visiting longtime favorite parks, museums, entertainment, sports, and restaurants. She believes in working hard, but smart, so she has plenty of free time to do the things she enjoys.

On weekends or after a long day in the office, you may find her walking, reading mystery novels, catching up on TV series, or watching sports with her husband. She also likes to sew in her spare time.

Meet Dr. Mariel Cotton

Growing up in Rockford, Dr. Cotton dreamed of becoming a marine biologist, and has even traveled to the Galapagos Islands and a remote island of Belize to snorkel and study coral reefs.


She attended the University of Notre Dame for her undergraduate studies, earning her BS in Science-Business. During her time there, she was active in a wide variety of activities including campus magazine design and volunteering with the Pediatric ward of a local hospital.

She was also on the Multicultural Affairs Committee within student government and mentored first-year students as a peer advisor and a diversity educator.

After deciding on dentistry over deep-sea diving, Dr. Cotton earned her DMD at Southern Illinois University, where she held a leadership position within the Delta Sigma Delta dental fraternity. She once again held several positions in student government, specifically on the Student Clinic Advisory Committee and the Quality Control Committee.

She participated in a dental mission trip to Jamaica during this time and mentored younger students by working as a tutor. Dr. Cotton was also the proud recipient of the James R. Schmidt Restorative Dentistry Award for tenacity, creativity, and excellence in restorative dentistry.

After dental school, she continued on to the University of Colorado for her orthodontic residency and earned her MSD for her research on preventative measures for white spot lesions during orthodontic treatment. Her love of learning new things and her passion for art, science, and helping others make being an orthodontist the perfect job for her.

Family Life

Outside of the office, Dr. Cotton loves to explore all the activities available in the greater St. Louis area. She and her husband recently purchased bicycles and are looking forward to hitting all the local biking trails.

They also enjoy having so many sporting events, museums, parks, restaurants, and wineries nearby. Sometimes St. Louis just isn’t enough, though – Dr. Cotton and her husband plan a road trip every year.

Her favorite involved visiting six different national parks, with her husband proposing to her as they were canyoneering in Zion National Park. When she’s not in the office helping patients transform their smiles, she loves cooking, working on art projects (especially watercolors), reading, hiking, and camping.

Dr. Julie McCray
Meet Dr. Kimberly Baptist

We're excited to announce that Dr. Kimberly Baptist has joined our practice, and will be working alongside Dr. Mastroianni at our Glen Carbon and O’Fallon locations. The entire Amazing Smiles team is thrilled to have her on board!


Dr. Baptist grew up in Mt. Prospect, IL, and graduated from the University of Illinois with a BS in Science. She then went on to attend the SIU School of Dental Medicine, and finally to St. Louis University for her orthodontic residency.

During college, she worked for a school district designated for children with special needs, first as a teacher’s assistant, and then later at their outdoor education center where she coordinated and led daily activities such as hiking, boating, fishing, and games.

More recently, she worked with Health and Dental Care for Kids, treating patients in lower income areas. She also assisted the Cleft Lip and Palate Team this past year at Cardinal Glennon Hospital.

Dr. Baptist takes pride in the quality of care she delivers to patients, and they have been impressed with her excellent chairside manner and the comfort they feel during treatment.

Outside the Office

When she isn’t in the office, you can often find her surrounded by rescue pups. She adores being a pet foster parent and volunteering at local animal shelters.

She enjoys rock climbing, hiking, and participating in other outdoor activities. Her other hobbies include crafting and gardening.

Having Dr. Baptist join Amazing Smiles will allow us to continue the quality of care and excellence you are accustomed to. Her presence will also allow us to open up additional appointment dates and times, and be more readily available for our patients.

Thank you for your incredible support, and we hope that you will join us in giving Dr. Baptist a warm welcome to our practice!

what patients rave about
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I am so impressed with Mastroianni Orthodontics. I’ve been concerned about my 8 1/2 year-old son’s baby teeth falling out and permanent teeth coming in crooked. I called Mastroianni Orthodontics and asked if my son was too young to be screened for braces, as I wanted to catch any problems early. The staff members answering the phone were friendly, knowledgeable, and explained to me that most kids should be screened by 9 or 10. So, I was on target. They also explained to me – to my shock and surprise! – that my initial visit, exam and x-ray for the screening was free of charge.
Trish C.