Rapid Prototyping in Correction of Craniofacial Skeletal Deformities

The skull of a human being, comprising two parts: the cranium and the maxillofacial bone, is a bony structure in the head that forms a cavity for the brain and supports the structures of the face. The functions of the skull include protection of the brain, fixing the position of the eyeballs and ears, compositing the oral cavity and airway. Bone deformities in the craniofacial area, including acquired deformities (such as defects result from oncological resection and trauma, and micrognathia syndrome after mandibular condyle injuries), and congenital deformities (various craniofacial syndromes, such as hemifacial microsomia) will create tremendous cosmetic and functional handicaps (Mehta & Deschler, 2004). Such deformities heavily affect the patients’ quality of life and pose a vast challenge to craniofacial surgeons. Various methods, including autogenous bone grafting (free bone grafting and vascularised grafting of compound tissue flaps), and alloplastic and allogeneic materials, have met with limited success (Boyne, 1973; Tideman et al., 1998; Samman et al., 1999). To achieve satisfactory esthetic and functional reconstruction using the traditional methods remains extremely challenging. At present most of the mandible restoration implants are fabricated by hand forming technique (Boyne, 1973; Tideman et al., 1998; Samman et al., 1999; Eufinger et al., 1997; Stojadinovic et al., 1999). The method involves pre-bending the reconstruction plate on the stereolithography model to cover the defect. Bone graft also was traditionally adapted on the sterilized stereolithography model during the operation to reconstruct the facial defect. The precision of fit and durability of implant mainly relies on the abilities of the technicians and surgeons. Rapid prototyping refers to a group of techniques that are used to produce stereolithographical models based on digital images, including reverse engineering (RE), computer-aided design (CAD), rapid prototyping (RP), etc. RE is a viable approach to create a 3-dimensional virtual model of an existing physical part by measuring an object using 3dimensional scanning technologies such as laser scanners, structured light digitizers, computed tomography (CT) or magnetic resonance (MR). CAD takes advantage of computer technology to aid in the design and, especially, the drafting (technical and engineering drawing) of a part or product. It is both a visual (or drawing) and symbol-based method of communication whose conventions are particular to a specific technical field. RP takes CAD files and transforms them into thin, virtual, horizontal cross-sections.