Stereolithography is a constructive process for the manufacture layer-by-layer of plastic models using an ultraviolet laser to catalyze the polymerization of a liquid plastic solution ^{1) 2)}.

Computer-aided design (CAD) and computer-aided manufacturing (CAM) by stereolithography are already being widely used in industry for the design and manufacture of new parts and have already shown accuracy in reproducing the desired model. The only shortcoming of this technique is that it can only make one model at a time, a “prototype.” It cannot be used for mass production. It is precisely this property, namely making a prototype, that makes it so attractive in reconstructive surgery and implantation of prostheses, where each “part” has to be adapted to the unique anatomy of the patient. It was not until the early nineties that reports of the application of stereolithography to reconstructive surgery appeared in the literature ³⁾.

3D imaging does not allow image manipulation and surgical simulation on screen before surgery. The potential for generating 3D structural models from CT scans was conceived as early as 1980 ⁴⁾.

Many techniques have been proposed for surgical training as a learning process for young surgeons or for the simulation of complex procedures. Stereolithograpfy, , has been presented as an option for these purposes.

It is easier for the surgeon to understand the complexity of a case and plan the approach before any surgical procedure ^{5) 6)}.

Optimal craniotomy or craniectomy for maximal visualization of operative fields can be determined in individually tailored skull models using actual surgical tools. Anatomical configurations and relationships in cranial base bony structures, such as the jugular tubercle, occipitalcondyle, and jugular foramen, vary among individuals. It is important to estimate the extent of drilling of these bony structures before actual surgery. Anatomical variations must be accurately modeled for operative procedures to be realistically simulated. In addition, the presence of extradural tumors such as chordomas and chondromas, which are often associated with bone destruction, makes intraoperative orientation under a microscope much more difficult. Simulations provide the surgeon with accurate mental images of the anatomy that will be en countered ⁷⁾.

Three-dimensional models used in neurosurgical simulation to teach skull base anatomy through a transsphenoidal approach showed objective and subjective improvement in testing scores in neurosurgery residents. This study confirms that 3-D models are a useful educational tool ⁸⁾

Prototyping of cerebral vasculature models through stereolithographic methods have the ability to accurately depict the 3D structures of complicated aneurysms with high accuracy.

With improving and more widespread printing options, these models have the potential to become an important part of research and training modalities ^{9) 10)}.

The approach combining computer-aided design, stereolithography and surgical navigation could help managing the complex lesions in the skull base and craniofacial area requiring rigid reconstruction ¹¹⁾

Custom made implant ^{12) 13) 14)}.

The disadvantages of using skull models include the time and cost of making the models. Further more, hand-made models of the tumors, major vessels and nerves placed inside the skull models may not provide exact reproductions.

Current 3D MR imaging of intracranial structures with 3D computed imaging of the skull may be superior to hand-made models inside the skull model if used only for observation. For surgical simulation, however, skull models are considered superior to currently available computer-generated screen images; once skull models are made, they provide a more realistic tool that is easier to handle than computer graphics. Use of these models may be a transitional stage until the capabilities of computers are significantly expanded. Advances in computer hardware and software could lead to new surgical simulation techniques that are even more similar to the actual surgical procedure ¹⁵⁾.