Comparative assessment on the capability of two bleeding indexes to measure the concentration of thromboxane B2 in periodontal tissues. The aim of the study was to compare two bleeding indexes, the Gingival Bleeding Index (GBI) and the Gingival Bleeding Time Index (BTI) in evaluating the intensity of inflammation in deep periodontal tissues measured by the level of thromboxane B2 in the tissues themselves. Results showed that both bleeding indexes were closely correlated to tissue inflammation but that of the two, BTI is more significantly correlated. On the basis of these findings, the authors hope to see the application of bleeding indexes in clinical and research studies which can offer a graduated assessment of bleeding, thus increasing the specificity of this important diagnostic sign.