Tooth extraction triggers alveolar ridge resorption, and when this resorption is extensive, it can complicate subsequent reconstructive procedures that use dental implants. Clinical data demonstrate that the most significant dimensional changes in the ridge occur soon after tooth extraction. Here, we sought to understand whether a correlation existed between the rate at which an extraction socket heals and the extent of alveolar ridge resorption. Maxillary molars were extracted from young and osteoporotic rodents, and quantitative micro–computed tomographic imaging, histology, and immunohistochemistry were used to simultaneously follow socket repair and alveolar ridge resorption. Extraction sockets rapidly filled with new bone via the proliferation and differentiation of Wnt-responsive osteoprogenitor cells and their progeny. At the same time that new bone was being deposited in the socket, tartrate-resistant acid phosphatase–expressing osteoclasts were resorbing the ridge. Significantly faster socket repair in young animals was associated with significantly more Wnt-responsive osteoprogenitor cells and their progeny as compared with osteoporotic animals. Delivery of WNT3A to the extraction sockets of osteoporotic animals restored the number of Wnt-responsive cells and their progeny back to levels seen in young healthy animals and accelerated socket repair in osteoporotic animals back to rates seen in the young. In cases where the extraction socket was treated with WNT3A, alveolar ridge resorption was significantly reduced. These data demonstrate a causal link between enhancing socket repair via WNT3A and preserving alveolar ridge dimensions following tooth extraction.
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