Dr. Messieha has filled leadership positions at the National and State levels including:
- President, Board of Directors for the American Society of Dentist Anesthesiologists.
- Fellow, American College of Dentists.
- Fellow, International College of Dentists.
- Diplomate, American Dental Board of Anesthesiology
- Diplomate, National Board of Anesthesiology
- Fellow in General Anesthesia, The American Dental Society of Anesthesiology
- Past President of the Illinois Dental Society of Anesthesiology.
- Past President of the Dental Anesthesiology Research Group, The International Association for Dental Research.
- Past Secretary and member, the Board of Directors of the American Dental Board of Anesthesiology.
- Past Chair, The American Dental Education Association Council on Hospitals and Advanced Education Programs.
- Past Chair, The American Dental Education Association Section on Anesthesiology, Oral Surgery and Hospital Dentistry.
