Clinical Efficacy of Allogeneic Bone Plate Shell Technique for Alveolar Ridge Augmentation: A Systematic Review

The allogeneic bone plate shell technique has emerged as a minimally invasive alternative to autogenous block grafting for alveolar ridge augmentation, aiming to reduce donor-site morbidity while maintaining predictable hard-tissue outcomes. This systematic review evaluated the clinical efficacy, dimensional stability, and implant performance of allogeneic cortical plates used with the shell technique in human patients requiring ridge augmentation before implant placement. A comprehensive electronic search across PubMed/MEDLINE, Scopus, Web of Science, Embase, EBSCOhost, and Google Scholar was conducted from inception to June 2025. Studies were eligible if they involved adult patients treated with an allogeneic shell-type augmentation and reported at least one of the following outcomes: linear or volumetric bone gain, graft resorption, implant survival, marginal bone loss, histological findings, or complications. Seven clinical studies met the inclusion criteria, comprising retrospective and prospective cohorts, case series, and one retrospective comparative study, with sample sizes ranging from 10 to 372 patients and more than 500 augmentation procedures in total. The technique was predominantly applied to horizontal or combined horizontal/vertical defects in the maxilla and mandible using thin allogeneic cortical plates fixed with microscrews and compartments filled with autogenous chips and/or xenogeneic granules. Reported horizontal gains generally ranged from approximately 2.4 to 4.8 mm, with graft resorption as low as 0.2 mm or 8%-9% in some series. Implant survival consistently ranged from 99.4% to 100%, and complications such as dehiscence or plate mobility were infrequent and usually manageable. Within the limitations of non-randomized evidence and clinical heterogeneity, allogeneic shell augmentation appears to provide predictable ridge reconstruction and high implant survival while eliminating autogenous donor-site morbidity.