A histological investigation of allografts of mature mouse molars to an intrabony and an extrabony site.

Fully developed mandibular third molar teeth, allografted across an H-2 plus multiple non-H-2 barrier to the tibial shaft medulla and renal subcapsular site in mice, were examined histologically over a 12-month period after transplantation. Cellular degeneration within the pulp chamber occurred in the immediate post-transplantation period and was followed by pulp chamber repopulation by a vascular fibrous connective tissue during the first 14 days after transplantation. Progressive regeneration of the grafts occurred and was characterized by irregular tubular dentine formation followed by more organized tubular dentine deposition on the pulp chamber walls. Allografts at both sites eventually underwent rejection, and it was apparent that grafts at the subcapsular kidney site were rejected in a shorter time (35 to 56 days) than those at the tibial shaft site (56 to 70 days). When mature teeth were allografted to the tibial shaft medulla across multiple minor (non-H-2) barriers alone, similar changes were observed with grafts undergoing rejection 56 to 70 days after transplantation. External root resorption and ankylosis were not prominent features and periodontal ligament reorganization was not observed in any of the grafts.