ObjectivesThe aim of this retrospective case series was to evaluate the efficacy and volume stability of a customized allogeneic bone block (CABB) for the hard tissue reconstruction of severely atrophied anterior maxillary ridges.Materials and methodsHard tissue alterations between baseline (T1), 2-month follow-up (T2), and 6-month follow-up (T3) cone-beam computed tomography scans were evaluated with semi-automatic segmentation. Following automatic spatial alignment of the datasets, 3D subtraction analysis was performed. The volume stability of the inserted allogeneic bone block was determined on the basis of the ratio of the T3 and T2 hard tissue volumes.ResultsThe newly formed hard tissue volume at T2 averaged at of 0.75 cm3± 0.57 cm3, whereas at T3, an average of 0.52 cm3± 0.42 cm3volumetric hard tissue gain could be detected. The T3/T2 ratio was found to be 67.83% ± 18.72% on average. The dice similarity coefficient between the T2 and T3 hard tissue models averaged at 0.73 ± 0.15.ConclusionsCancellous CABBs are a reliable option for the reconstruction of severely atrophied alveolar ridges. The resorption rates of these grafts are similar to those found in the literature; however, with precise manufacturing and proper intraoperative flap management, the resorption rates may be reduced.Clinical relevanceWith precise knowledge of the resorption patterns, the shape of blocks can be altered in the future to compensate for the volumetric loss.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00784-023-05015-0.