Author(s): Shi-zhu Bai1 , Zhi-hong Feng1 , Rui Gao1 , Yan Dong1 , Yun-peng Bi1 , Guo-feng Wu1 and Xi Chen1
War and traumatic injuries may result in maxillofacial soft-tissue defects and deformities; for instance, auricular, nasal, or orbital defects or complex multi-organ defects and deformities . Defects in the maxillofacial region have severe and complicated impacts on the patient's physical and mental health, leading to deficits in functions such as mastication, speech, and deglutition. Moreover, such injuries also result in serious facial deformations, thus handicapping the patient's daily activities. Some patients who have suffered maxillofacial defects may show suicidal tendencies, and the army's morale and ability to recruit new soldiers may be adversely affected. Thus, it is of great significance in the field of military medicine to rehabilitate and reconstruct the lost function and damaged appearance caused by maxillofacial war injuries and help these patients return to society.
Surgery was routinely performed to reconstruct maxillofacial defects and deformities. However, the normal appearance and structure of the facial region is often beyond the capability of surgical reconstruction, considering the subtle and intricate characteristics of the local tissue and structures. The application of a maxillofacial prosthesis is an alternative to reconstructive surgery, either because of the poor psychophysical condition of the patient or because of excessive tissue loss . However, the traditional method of fabricating maxillofacial prostheses includes several complex steps; it is a labor-intensive and time-consuming task, and the final results mainly depend on the experiences and skills of the clinician .
The application of computer aided design/computer aided manufacturing (CAD/CAM) in this field has opened up a new approach to the fabrication of maxillofacial prostheses [4-10]. The School of Stomatology, Fourth Military Medical University has been researching this field since 2001 and has developed an intelligentized rapid design and manufacturing system for maxillofacial prosthesis fabrication. The system consists of three components: digital impressions, simulation design of the prosthesis, and rapid manufacturing of the prosthesis.
This study was carried out at the Department of Prosthodontics of the School of Stomatology, the Fourth Military Medical University, Xi'an. This hospital provides treatment for both military and civilian patients. The study was approved by the Institutional Review Board of the School and was conducted in accordance with the principles of the Declaration of Helsinki. A clinic assistant informed all subjects about the nature of the study. Informed consent was obtained from each subject who agreed to participate in the study.
Maxillofacial digital impression
Digital data were obtained by a structured-light three-dimensional (3D) scanning system and a computed tomography (CT) scanning system.
Structured-light 3D scanning
The 3D sensing scanning technique integrated several 3D non-contact measurement techniques, such as the structured light technique, the phase measurement technique, and the computer vision technique. Several narrow stripes of light were projected onto the surface of the target object and produced lines of illumination that appeared distorted from other perspectives than that of the projector, so an exact geometric reconstruction of the surface shape...