My gums look lower after guided tissue regeneration. Why is that?

Gums looking lower right after surgery is a common and natural course. Before surgery the gums were swollen with inflammation and so looked higher than they really were; with the inflammation removed and the swelling gone, they appear to have receded. Despite the outward appearance, bone is filling in along the grafted material underneath, and bone regeneration usually progresses over several months. However, if the barrier membrane becomes exposed, or pus or severe pain develops, infection is possible, so come in right away.