Guided tissue regeneration was successfully used to treat a patient who had a mucogingival defect associated with interdental bone loss. The defect involved the mandibular left central incisor, which exhibited 6.0 to 7.0 mm of attachment loss on the facial, mesial, and distal aspects. A regenerative procedure consisting of critic acid demineralization and placement of a demineralized freeze-dried bone allograft and Gore-Tex membrane was performed. At 8 months, a gain of 4.5 to 5.0 mm, or 64% to 83%, in clinical attachment levels was demonstrated. Root coverage was 86%.