Use of Combination of Allografts and Xenografts for Alveolar Ridge Preservation Procedures: A Clinical and Histological Case Series

Aim: To perform a clinical and histomorphometric evaluation of a combination of allograft and xenograft for alveolar ridge preservation (ARP) procedures. Methods: Seven consecutive cases in need of nonmolar tooth extraction and posterior implant placement were treated by ARP, using a combination of a cortico-trabecular allograft and a mineralized xenograft. All sites received a minimally traumatic tooth extraction, bone graft, collagen membrane placement, and flap closure as possible. Healing time was 4 months for the majority of cases. After tooth removal and just before implant installation, clinical measurements were taken; after the healing time, bone biopsies were taken. Results: All sites healed uneventfully. Bone dimensional changes were small; a mid-buccal vertical bone gain of 1.0 mm (SD, 3.2 mm) and a horizontal bone reduction of 1.6 mm (1.6) were recorded. Histomorphometric analysis showed large variability in percentages of new bone (mean 22.3% [17.3], range: 1.8%-35.2%) and a considerable amount of residual bone graft material (mean 33.2% [13.2], range: 5.5%-45.8%). Conclusion: Favorable clinical results were observed after the use of the combined bone graft, although a large variability in tissue proportions was present at 4-month healing time, especially for new mature bone.