Horizontal ridge augmentation with demineralized allograft layered with xenograft – A prospective cohort study

BACKGROUND: This study evaluated clinical, radiographic, and histologic outcomes of horizontal ridge augmentation using a layering technique with demineralized freeze-dried bone allograft (DFDBA) internally and deproteinized bovine bone mineral (DBBM) buccally, covered by a native bilayer collagen membrane. Primary outcomes included horizontal bone gain, graft shrinkage, and vital bone formation. METHODS: In this prospective single-arm study, adult patients requiring horizontal ridge augmentation prior to implant placement were treated with the layering technique (DFDBA and DBBM). Cone beam computed tomography scans were obtained preoperatively (T0), immediately postoperatively (Tim), and after 6-9 months (T2). Ridge widths were measured at 3, 5, and 7 mm apical to the crest. Linear mixed-effects models assessed dimensional changes and the influence of the DFDBA:DBBM ratio on the outcomes. Bone core biopsies were collected at implant placement for histologic and histomorphometric analysis. RESULTS: Fifteen patients completed the study. Mean horizontal bone gain was 3.68 ± 1.20, 3.98 ± 1.56, and 3.91 ± 1.77 mm (all p < 0.001) at 3, 5, and 7 mm respectively. Linear graft shrinkage was 1.76 ± 0.95, 1.82 ± 1.11, and 1.72 ± 0.96 mm at the respective levels (all p < 0.001). A higher DFDBA:DBBM ratio significantly increased shrinkage at 3 mm (p = 0.015). Histology (n = 7) showed 30.97 ± 16.71% vital bone, 21.41 ± 10.63% residual graft, and 47.62 ± 18.51% marrow/connective tissue. CONCLUSION: The DFDBA-DBBM layering technique achieved significant horizontal bone gain with predictable modelling and favorable vital bone formation, supporting its use as a viable augmentation approach pending further comparative studies. KEY POINTS: The layering technique of internal demineralized freeze-dried bone allograft and outer deproteinized bovine bone mineral for guided bone regeneration predictably increased horizontal ridge width, resulting in approximately 3.6 - 4 mm of horizontal bone gain. The technique demonstrated favorable dimensional stability with graft shrinkage of approximately 1.7-1.8 mm. The augmented sites showed clinically relevant amounts of vital bone formation (approximately 31%), supporting the biological effectiveness of the layered grafting strategy.