Introduction. To determine the primary events of gingival microvascular complex damage caused by inflammation (28 days) on an acidotic model of periodontitis in 36 white mongrel rats, and to clarify regulatory factors of the structural recovery after metabolic correction (14 days). Materials and methods. Expression and severity of gingival inflammation were visually analyzed with an ANOVA test. The gingival tissue specimens were examined (x 4000-6000) after 42 days with a transmission electron microscope JEM-100 CX II (JEOL, Japan). Results and discussion. Vacuolation of the endothelial cells' cytoplasm, thickening and loosening of the basal lamina, narrowing of the microvascular lumen, aggregation of the red blood cells and dilation of perivascular space were characteristic features of inflammatory derangement. A significantly lower severity of gingival inflammation (p < 0.05), thin condensed basal lamina …