Biologic mechanical advantages of 3 different cranial bone grafting techniques for implant reconstruction of the atrophic maxilla.

Objective: The purpose of this study was to test the mechanical capacities of 3 different bone grafting techniques in the atrophic maxilla when co-stabilized with dental implants. Reconstruction of the atrophic maxilla is a difficult clinical challenge and implants cannot be placed without adequate bone.

Methods: The biomechanical performance of 3 different grafting techniques was evaluated in vitro using a maxillary model, cadaveric cranial bone blocks, and dental implants. A maxillary model fabricated from polyurethane (sawbone) was selected as a substrate for this study because of consistency in shape, size, and mechanical properties. This anatomic model was more consistent than different cadaveric maxilla, where significant variation was found to exist among atrophic specimens. Cadaveric cranial bone graft blocks were secured to the model maxilla (sandwich, ridge only, and sinus inlay) with a dental implant. The strength of the implant/bone graft complex was tested to failure in an Instron machine (Instron Inc, Canton, MA).

Results: The 3 bone grafting methods showed significantly different deformation and strength characteristics. The sandwich technique enhanced resistance to deformation under higher imposed loads. The location of the graft influenced the overall mechanical performance (eg, the ridge onlay) and showed a significantly higher resistance to compressive loads applied toward the alveolar ridge (mastication force).

Conclusions: The ridge onlay grafting procedures created a higher biomechanical tolerance to imposed load than the sinus grafting (sinus inlay). Sinus grafting, although successful, was not the most ideal location for immediate mechanical loading resistance when compared with ridge augmentation in this in vitro model.