In mandibular reconstruction, it is necessary to know the exact, three-dimensional extent of the mandible and its defect; the bone graft must be the exact size and dimension of the defect, to assure a precise three-dimensional configuration of the mandible. Previously, the bone graft had to be reshaped during the operation by trial and error, often a time-consuming procedure. The operative procedure has been simulated in advance using three-dimensional, solid models, which has shortened the operating time required.