Bone reactions around transplanted roots

The aim of this experiment was to study endosteal bone reactions around roots transplanted into an edentulous crest, and the role, if any, of periodontal ligament (PDL) remnants preservation. After extraction of premolars and healing of the crests, 20 roots in 5 dogs were transplanted into bone cavities prepared in the edentulous areas. Roots implanted in the lower and upper right cavities had their PDL remnants preserved while those grafted in the left cavities had their surface planed and dried. After 5 months, the roots with surrounding bone were removed. 2 bone areas were delineated at the mesial aspect of each root, one immediately adjacent to the alveolar wall and the other distal to it. Results demonstrated that bone volume was higher in the proximal versus distal area in the maxilla and mandible preserved groups. The adipocyte content of the marrow spaces, an index of bone maturation, was less pronounced in the proximal versus distal areas in the preserved groups. The number of osteoclasts was higher in the proximal zone in the preserved groups as were the extents of the different bone remodeling activities. The results indicate that the organization of PDL around transplanted roots is associated with rearrangement of the bone tissue surrounding the grafts. This process of long duration might be an adaptation to the likely low mechanical strains applied on bone through the root. Transplantation of PDL-damaged roots did not induce such events in the surrounding bone which had acquired the structure of an edentulous crest.