Anterior atrophic mandible restoration using cancellous bone block allograft

Background: Bone block grafting may be required to restore the alveolar process prior to implant placement in Kennedy Class IV partial edentulism of the anterior mandible.

Purpose: Evaluate the application of allograft cancellous bone blocks for the augmentation of the anterior atrophic mandible.

Materials and methods: Fourteen consecutive patients underwent augmentation with cancellous bone block allografts in the anterior mandible. A bony deficiency of at least 3 mm horizontally and up to 3 mm vertically according to computerized tomography para-axial reconstruction served as inclusion criteria. Following 6 months, 26 implants were placed and a cylindrical sample core was collected. All specimens were prepared for histological and histomorphometrical examination. The rehabilitation scheme was two dental implants, placed in the lateral incisor area, supporting a 4-unit implant-supported prosthesis.

Results: Twenty-four blocks were placed in 14 patients. Mean follow-up was 26 ± 17 months. Mean bone gain was 5 ± 0.5 mm horizontally, and 2 ± 0.5 mm vertically. Twenty-six implants were used. Marginal bone loss at last follow up did not extend beyond the first thread. Block and implant survival rates were 91.6% and 100%, respectively. All patients but one received a fixed implant-supported prosthesis. Histomorphometrically, the mean fraction of the newly formed bone was 42%, that of the residual cancellous block-allograft 17%, and of the marrow and connective tissue 41%.

Conclusions: The potential of cancellous bone block allografts for reconstruction of Kennedy Class IV partial edentulism in the anterior mandible seems promising but still has to be evaluated scientifically in long-term observations.