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

An experimental model designed for the investigation of tooth transplantation immunobiology is presented together with the results of a long-term histological study of mature mouse tooth isografts transplanted to an intrabony site (tibial shaft medulla) and to an extrabony site (renal subcapsular site). Mature mouse mandibular third molars were isografted to the tibial shaft medulla and renal subcapsular kidney site in inbred C57BL/6 strain mice and observed histologically over a 6-month period. Isografts at both sites were observed to undergo initial pulpal degeneration with subsequent progressive regeneration as determined by post-transplantation dentine formation. Tibial shaft isografts were surrounded by bone and underwent progressive reabsorption beginning at the coronal dentine, exposed by occlusal wear prior to transplantation, while grafts to the subcapsular kidney site did not become surrounded by bone nor exhibit coronal resorption. Varying degrees of external root resorption and ankylosis of teeth transplanted to the intrabony site were observed, and signs of periodontal ligament reorganization were not seen in isografts at either site.