A total of 30 mandibular, buccal class II furcation defects were treated in 22 subjects using a regenerative surgical therapy that included citric acid root conditioning and coronally positioned flaps secured by crown-attached sutures. In addition, grafts of freeze-dried, decalcified allogenic bone were placed in 16 of the 30 defects. The effect of the therapies was evaluated from a series of soft and hard tissue measurements. These measurements demonstrated notable improvement 12 months following therapy. On the average, 67% of the defect volume became filled with bone. 43% of treated defects were completely closed by bone fill. No difference was observed between defects treated with and without bone grafts.