beta-Tricalcium phosphate in the early phase of socket healing: an experimental study in the dog

The aim of this experiment was to analyze processes involved in the incorporation of beta-tricalcium phospate (TCP) particles in host tissue during healing following tooth extraction and grafting.

Five beagle dogs were used. Four premolars in the maxilla ((3)P(3), (2)P(2)) were hemi-sected, the distal roots were removed and the fresh extraction socket filled with TCP. The tooth extraction and grafting procedures were scheduled in such a way that biopsies representing 1 and 3 days, as well as 1, 2, and 4 weeks of healing could be obtained. Tissue elements such as cells, fibers, vessels, leukocytes and mineralized bone were determined. In deparaffinized sections structures and cells that expressed Tratarate resistant acid phosphate, alkaline phosphatase, and osteopontin were identified by the use of markers.

The porosities of the TCP particles were initially filled with erythrocytes that subsequently were replaced with mineralized bone. Some of the graft material was invaded by mesenchymal and inflammatory cells and disintegrated. Thus, small membrane bound granules appeared in the granulation tissue and the provisional matrix. In the process of hard tissue formation, partly mineralized (modified) TCP particles became surrounded by ridges of woven bone.

It was demonstrated that the early healing of an extraction socket that had been grafted with beta-TCP involved (i) the formation of a coagulum that was (ii) replaced with granulation tissue and a provisional matrix in which (iii) woven bone could form. In this process the biomaterial was apparently involved.