Changes in alveolar bone height and width following ridge augmentation using bone graft and membranes

Clinical observation suggests the amount of bone height and width created during guided bone regeneration (GBR) to augment alveolar ridges is not retained during healing. A study was designed to determine: 1) whether the amount of osseous structure 4 months postoperatively after GBR was significantly less than the amount surgically created; and 2) if this change was uniform over the area treated.

Nineteen extraction sites (10 patients) were treated with GBR prior to placing endosseous implants. Allograft (DMFDB) and a bioabsorbable membrane were employed. Standardized measurements were taken of alveolar height and width 1) prior to augmentation; 2) after placement of graft and membrane; and 3) following 4 months of healing. Width measurements were taken 3 mm, 5 mm, and 10 mm from the crest at 3 intervals: the mesio-distal midpoint of the edentulous area and 3 mm mesial and distal to the midpoint. Height measurements were recorded at the mesio-distal midpoint and points 3 mm mesial and distal to the midpoint.

Loss in width of supplemented bone after 4 months of healing ranged from 52.1% to 58.0% 3 mm from the crest, 47.6% to 67.4% 5 mm from the crest, and 39.1 % to 46.7% 10 mm from the crest. Loss of augmented height averaged 14. 7% in the center of the edentulous area but ranged from 60.5% to 76.3% 3 mm mesial and distal to the midpoint.

The results indicate significant non-uniform loss of augmented alveolar height and width during GBR healing. The implications of these findings impact preoperative augmentation planning for endosseous implantology.