Bone formation following guided tissue regeneration (GTR).

The principle of guided tissue regeneration using barrier membranes has become an accepted method for the treatment of teeth with severe osseous defects and furcation involvement. A technique was developed using an expanded polytetrafluoroethylene soft-tissue patch, 1 mm thick (W.L. Core and Assoc., Flagstaff, AZ), in conjunction with an alloplast hydroxyapatite bone substitute (HA-500, 40-60 mesh) (Orthomatrix, Minneapolis, MN), for space maintenance in severe osseous defects. A case report is presented which demonstrates the successful use of this method, and includes a fourth-year re-entry procedure that illustrates the complete bone fill and obturation of a severe vertical defect and Class II furcation of a mandibular first molar.