The Pennsylvania Dental Association (PDA) exists to support member dentists, promote the art and science of dentistry and uphold the dental profession. PDA is a voluntary state organization comprising of approximately 5,200 member dentists. It is a constituency of the American Dental Association (ADA), the largest and oldest national dental society in the world. Mission: The purpose of the Pennsylvania Dental Association shall be to serve the public, improve their health, promote the art and science of dentistry and represent the interests of its members and the people they serve.