The regeneration of the periodontal structure for avulsed teeth extended dry times has been a goal of dentists. The aim of this study was to investigate a new strategy of delayed replantation for avulsed teeth that were not suitable for immediate replantation.Extracted dog's premolar teeth were maintained in a dry environment for a month after isolation and proliferation of the periodontal ligament (PDL) cells. Then, tooth roots coated with 1 x 10(6) cultured autologous PDL cells were autotransplanted in artificial sockets created in the mandible. The dogs were sacrificed 60 days after transplantation. Histologic analyses showed that a root-PDL-bone complex was found in all cases of the PDL cell-loaded samples.The new PDL-like connective tissue was located between the alveolar bone and the transplanted roots, with fibers inserting into the newborn cementum on one end and alveolar bone on the other. For the control samples, no PDL-like tissue was found, and ankylosis was commonly observed.The results indicated that cultured autologous PDL cells assist in the re-establishment of periodontal architecture of autotransplanted teeth that is devoid of viable periodontal cells.