It is recognized that the mandibular reconstruction with free flap allows for both functional and aesthetic restoration. The flap must be used for reconstruction of a smooth lower mandibular contour and also the alveolar bone to allow dental rehabilitation. The double-barrel fibula free flap does respond well to these imperatives, but it increases risk of vascular complications. To overcome these risks, we propose a single-barrel fibula free flap, positioned at the alveolar level and a customized 3D implant, designed by computer-assisted surgery, at the basilar level. The interest of the single-barrel fibula associated with a customized 3D implant compared to the double-barrel fibula free flap is twofold: it decreases the vascular risks associated with the plication of the second pedicle and allows patients to have a pedicle of greater length. It also allows them to have a good cortical bone placed in the alveolar bone to rehabilitate the mastication function.