Assessment of Vertical/Horizontal Ridge Augmentation in Atrophic Alveolar Ridge Using Autogenous Onlay Versus Inlay Grafting Techniques: A Systematic Review

Alveolar ridge atrophy presents a major challenge in implant dentistry, often necessitating surgical augmentation to restore adequate bone volume for predictable implant placement. Among the various autogenous grafting approaches, the inlay and onlay techniques are widely utilized, yet their comparative clinical efficacy remains unclear. This systematic review aimed to evaluate the outcomes of vertical and horizontal ridge augmentation using inlay versus onlay grafting techniques in atrophic alveolar ridges. An extensive electronic and manual search of major databases was conducted in accordance with PRISMA guidelines, and eligible randomized controlled trials and comparative clinical studies assessing autogenous grafts were included. Six studies met the inclusion criteria. Both techniques produced appreciable gains in bone height and width; however, the inlay technique demonstrated more favorable results in terms of graft stability, reduced volumetric resorption, and improved soft tissue healing. Inlay grafts benefited from superior vascularization and mechanical protection due to their placement within the osteotomized host bone, resulting in fewer complications and better preservation of augmented volume. By contrast, onlay grafts showed higher rates of resorption, flap dehiscence, and graft exposure, particularly in vertical augmentations where soft tissue tension and limited vascular supply are significant challenges. Despite promising findings, heterogeneity among studies and limited long-term data restrict definitive conclusions. Further well-designed randomized controlled trials with standardized protocols and extended follow-up are needed to strengthen the evidence base. Overall, the inlay technique appears to offer predictable and stable outcomes, particularly in complex augmentation scenarios.