Purpose: To evaluate the efficacy of using a customized xenograft shell with a 1:1 mixture of particulate xenograft and autogenous bone for the reconstruction of horizontally deficient anterior maxillary alveolar ridges. Materials and Methods: CBCT images of the atrophic maxilla of eight patients were acquired and generated into 3D models. The data were transferred to a 3D printer for fabrication. During the surgery, xenograft blocks were manually sliced and customized on the 3D-printed models into bone shells. Then they were fixed to the atrophic site, and the gap was augmented with a 1:1 mixture of particulate xenograft and autogenous bone. Results: Clinical assessment showed no adverse effects; however, one patient exhibited wound dehiscence. The mean difference between the preoperative and 6-month postoperative CBCTs showed a net average bone gain of 4.06 mm at 2 mm from the crest and 4.34 mm at 5 mm from the crest, which was statistically significant. On the other hand, a statistically significant graft resorption of 1.41 mm at 2 mm from the crest and 2.19 mm at 5 mm from the crest was found when the mean difference between the immediate and 6-month postoperative CBCTs was calculated. Conclusions: Within the limitations of the study, the use of xenograft shells as a barrier for maxillary alveolar ridge reconstruction is a predictable technique; however, further investigations regarding the required time for graft consolidation are required.