Gingival inflammatory symptoms are aggravated during pregnancy. In vitro studies suggest a hormonal influence on the
plasminogen activator inhibitor type 2 (PAI-2), and a disturbed balance of the fibrinolytic system could help to explain pregnancy
gingivitis. Gingival crevicular fluid (GCF) was sampled in 14 women in pregnant and post-pregnant states. The gingival condition was assessed by the gingival index of Løe & Silness (GI) and the amount of bacterial plaque by the plaque index of Silness & Løe (PI). The ratio of sites with
gingivitis to sites with bacterial plaque was calculated (G/P-ratio).
Antigen levels of
tissue plasminogen activator (t-PA),
urokinase-type plasminogen activator (
u-PA),
plasminogen activator inhibitors type 1 (PAI-1) and
PAI-2 in GCF were determined with ELISAs and
17 beta-oestradiol and
progesterone in serum with radioimmunoassays. For each individual the differences (delta) in
hormone levels and PAs and PAIs between pregnancy and post-pregnancy were calculated. Based on differences in G/P-ratio between pregnancy and post-pregnancy, subgrouping was done into a high-reacting and a low-reacting group. For the total group, the mean G/P-ratio was 2.0 during and 1.2 after pregnancy (p = 0.064). A statistically significant correlation between delta
progesterone and delta
PAI-2 was noted: the higher delta
progesterone, the lower delta
PAI-2. No other significant correlations between
hormone levels and components of the fibrinolytic system were found. For the total group of women, the concentrations of
PAI-2,
PAI-1 and t-PA were significantly higher during than after pregnancy. The individuals in the high-reacting group, however, showed a lower or unchanged production of
PAI-2 during pregnancy, while those in the low-reacting group showed a greatly increased production. The lower inhibitory capacity in terms of a low production of
PAI-2 during pregnancy in women with a higher inflammatory reaction indicates that the components of the fibrinolytic system may be involved in the development of pregnancy
gingivitis and implies that
PAI-2 serves as an inhibitor of importance for tissue proteolysis. The present finding contributes to the explanation of pregnancy
gingivitis.