The purpose of this study was to examine the tissue response to experimental furcation perforations immediately treated with Super EBA, Ketac Silver, MTA and Emdogain using surgical microscope. Forty experimental furcation perforations were created in the mandibular and maxillary premolars and molars of 4 adult dogs and immediately repaired with experimental materials. The animals were sacrificed after 16 weeks and radiographic and histologic results were evaluated. The results were as follows. 1 All materials tested in this experiment revealed a certain degree of extrusion of the filling materials and infiltration of inflammatory cells into the periodontal space. Except MTA group, epithelial down-growth of the surrounding gingiva was found in all experimental groups. 2. Both Ketac Silver and Emdogain group showed the greatest degree of inflammatory reaction and bone resorption. 3. Super EBA group showed moderate inflammation and newly bone formation under the perforation area. 4. MTA group showed minor inflammation, new bone regeneration toward restorative materials and partially cementum growth onto the surface of the material. This group demonstrated a favorable prognosis.