Stereolithographic modeling technology applied to tumor resection.

One of the goals of mandibular reconstruction after tumor resection is a return to premorbid form and function. The typical reconstruction includes a titanium bone plate and bone replacement with a graft or vascularized flap. Stereolithography (SLA), which began to be used in the 1980s, 1,2 is a valuable adjunct to traditional methods of treatment planning for reconstruction following resection of tumors, developmental abnormalities, or trauma reconstruction. 3 SLA uses computer technology and medical image processing techniques to generate a complex plastic 3-dimensional (3D) model from computed tomography (CT) scans. When stereolithographic technology is incorporated into the reconstruction procedure, the workup and operative phases can be improved and treatment can be enhanced. SLA technology can be applied to the correction of congenital craniofacial anomalies, dentofacial deformities, and maxillofacial defects resulting from trauma or tumor resection. The accuracy of SLA models has been well documented. 2,4‐6 The process involves CT scans, computers, and acrylic photo polymerizing resin. In addition to resin, these models (or custom-made implants) can be fabricated from a starch-cellulose material (as for patient 1), hydroxyapatite (HA), calcium phosphate cements, or other plastics. Resin tends to be sturdier; starch models are more friable and must be handled more carefully to avoid crumbling of the material. Even though the starch models are less expensive than the resin models, the handling characteristics make the resin models more desirable when using them for planning reconstructive surgeries. In addition, the resin models can be sterilized and brought to the operating field; starch models would be destroyed by autoclave temperatures. The basic components of the stereolithographic apparatus include a controlling computer, an ultraviolet laser with optics, galvanometer-coupled mirrors, a liquid polymer tank, and a movable platform within the tank. Accurate stereolithographic models (SLMs) are influenced by numerous steps in the design process, and care must be taken in each step if the process is to generate a model that is free of fabrication errors. When models are made from nonresin materials, laser printer technology is used to layer the powdered material intermittently with a liquid phase adhesive. These 3D models can be used to preshape metallic implants that will be used in surgery. The length of implant plates and the number and lengths of required screws can be planned before surgery. 7 It is also possible to plan osteotomies by performing a surgical rehearsal on the model itself. Such a rehearsal allows measurement of the displacement of all bone segments and anticipation of the size and the form of bone grafts; using these techniques requires the development of reference points so that sectioned portions of the model can be replaced into their original positions (eg, using plaster or dental stone to create a base around the uncut model). This article presents a case series to show the use of stereolithography in mandibular tumor reconstruction.