Following initial examination, all patients underwent oral hygiene instruction and full-mouth supra- and sub-gingival scaling and root planning under local anesthesia. Patients were re-evaluated after completion of the initial therapy to determine their response to therapy and to confirm the need for periodontal surgery. Before surgery, for each pair of defects, one defect was randomly assigned to test (EMD) and one to control (OFD) treatment by toss of a coin. Both defects were treated at the same surgical time. When a patient presented with more than one pair of defects, only one pair was treated per day. Following local anesthesia, all sites were treated with reflection of a full thickness mucoperiosteal flap after intra-sulcular incisions. The exposed roots and osseous defects were debrided with hand instruments, and the surgical wound was rinsed with saline.