Scanning electron microscopy observations of initial clot formation on treated root surfaces.

This study presents the morphological sequence of events in initial blood clot formation on various root surfaces of freshly extracted human teeth. Four teeth with periodontal disease (PD) and three teeth without PD were extracted and the roots sectioned into halves. Those root surfaces with PD had four treatment areas: (1) intact periodontal ligament (PDL), (2) unplanned PD, (3) PD plus planed, (4) PD plus planed plus application of pH 1 citric acid (CA). The roots with no PD had three treatment areas: (1) intact PDL, (2) planed, (3) planed plus CA. Both root halves were reinserted together into the original extraction site. Each root half was then removed at either zero, one, two or four minutes and prepared for scanning electron microscope (SEM) evaluation. SEM observations suggested that plasma proteins were deposited initially on all root surfaces. Platelets and erythrocytes enmeshed in fibrin deposited most rapidly and consistently over the plasma protein layer where intact PDL was present. Similar observations were noted on the planed plus CA surfaces and appeared to occur at an earlier time than on the planed-only surfaces. A constant feature at all time periods was the absence of organized clot formation over the plaque-free zone of the PD root surfaces. By two minutes all surfaces, except the plaque-free zone of the PD area, appeared to have clot lysis occurring. While clot formation appeared to occur more rapidly over surfaces in the non-PD roots, no marked morphological differences in clot formation were observed between PD and non-PD teeth with similar root surface treatments.