After 60 to 90 days, newly formed woven bone forms a bridge across the entrance of the socket. The epithelium covering the bone is keratinized. Soft tissue healing at this stage has been completed. At 90 to 180 days after tooth extraction, the woven bone is gradually remodeled into cortical bone. A periosteum is established with collagen fibers from the lining mucosa inserting into the new cortical bone.