Mixed saliva was collected from 25 healthy young people before oral surgery, immediately after the operation and at control 4, 5 or 6 days later. The concentration of albumin, at-antitrypsin, anti-thrombin III, C1-esterase inhibitor, α2-macroglobulin, α2-plasmin inhibitor and plasminogen was measured in plasma (Cp) and saliva (Cs) samples from 12 patients by electroimmuno assay. The capacity of saliva samples to inhibit fibrinolytic activity in a euglobulin precipitate from a standard plasma was estimated on human fibrin plates (13 patients) and plasminogen-free fibrin plates (six patients). Normal saliva only showed a weak inhibitory effect on human fibrin and except albumin, none of the investigated proteins were found in measurable amounts. In postoperative saliva the concentration of recorded proteins varied among patients from 39 % to lower than 4 % of normal plasma concentrations. This contamination caused total neutralization of fibrinolytic activity during 6 hours, except in one patient. After 20 h the primary inhibitory effect decreased around 30 % on human fibrin. The ratio (Cs/Cp) of α2-plasmin inhibitor postoperative was significantly lower (P < 0.01) than the ratio of other proteinase inhibitors. The control samples contained negligible amounts of α1-antitrypsin and a2-macroglobulin in a few patients and showed a weak inhibitory effect on human fibrin. No inhibitors of fibrinolysis in saliva with physiological importance were discovered. The generation of plasmin in saliva after the operation is completely controlled by the high inhibitor capacity from plasma. However, the mixing of blood and saliva activates the fibrinolytic system and, as the supplement of fibrinolytic inhibitors from the ulcer in the postoperative period is insignificant, increased local fibrinolysis can develop. © 1978, Munksgaard International Publishers Ltd.. All rights reserved.
