Orthodontics has been a common dental treatment. The complete treatment often takes several years. In order to increase the satisfaction degree and reduce the gap problem, orthodontists and patients should have a sufficient communication between each other and reach the consensus prior the treatment. In case that the simulation system for the long-term treatment exists, the system definitely provides a good communication channel between orthodontists and patients. In this paper, we design a 3D dentist – patient communication system for simulation of orthodontics. The system first collect the clinical paradigms of orthodontic cases, which must contain the photos about the maxillofacial pre-, in-, and post-treatment. The paper simulates the treatment processes through tuning the 3D virtual model of oral and maxillofacial, including face, oral and teeth, to demonstrate the processes of the clinical paradigms. In addition, this research will be the first one, as we know until now, to provide the functions that the orthodontist can arbitrarily operate the 3D virtual model. The orthodontist can represent the corresponding 3D virtual model for a patient in a short time according to his/her status. Based on the orthodontic knowledge, the orthodontist can demonstrate the treatment processes, showing the moving of the teeth. The orthodontist can answer the possible questions from the patient about the treatment processes with the 3D model. Clearly, the system is an effective communication vehicle between the patient and orthodontist.