Alveolar ridge preservation at tooth extraction.

The principles of guided bone regeneration, which are at the core of contemporary periodontal therapy, have evolved into the present generation of barrier membranes, which greatly improve the overall result by not requiring primary closure. The supplemental addition of calcium sulfate to the graft materials appears to accelerate the rate of vital bone formation. In the future, these procedures are likely to become less invasive and more predictable, barrier membranes may not be needed and additional materials will be available that will accelerate the formation of bone.