Morphological and proliferative analysis of the healing tissue in human alveolar sockets covered or not by an e-PTFE Membrane: A preliminary immunohistochemical and ultrastructural study

Healing tissues of extraction sockets have been used, as autografts, for the treatment of periodontal bony defects. These tissues have proved to be more effective in inducing bone formation than mature bone. However, there are limited data regarding the nature and proliferative activity of its cells. The aim of this pilot study was to analyze the nature and the proliferative activity of cells present in newly formed tissue from human extraction sockets, covered or not by an e-PTFE membrane. The healing tissue of 6 pairs from human alveolar sockets covered or not by an e-PTFE membrane, collected 4 weeks after tooth extraction was analyzed. The specimens were observed using light and transmission electron microscopy (TEM). The immunohistochemical characterization of the tissues included type I collagen, osteonectin and bone sialoprotein detection. The proliferation rates of the tissues were obtained using PCNA labeling. Cells and extracellular matrix were labeled for type I collagen, osteonectin and bone sialoprotein, in both groups. PCNA antibodies revealed significant higher proliferation rates in the coronal areas than in the apical areas of the tissues, independent of which group they belonged to. TEM showed cells containing a Golgi apparatus, rough endoplasmic reticulum and mitochondria indicative of secretory cells, in both groups. In the apical area of the test and control groups, the extracellular matrix exhibited more bundles of collagen fibrils than in the coronal area. The cells of healing tissue of dental sockets are osteoblastic in nature. Additionally, they present higher proliferating rates in the coronal areas, independent of the use of the e-PTFE membrane.

Keywords
bone healing; guided bone regeneration; immunohistochemistry; transmission electron microscopy.