Haemoglobin concentration and oxygen saturation in dog gingiva with experimentally induced periodontitis

The index of haemoglobin concentration (Hb index) and apparent oxygen saturation (apparent SO2) were determined by a new, non-invasive method, tissue reflectance spectrophotometry. The Hb index was positively correlated with the haemoglobin concentration. The relationship between the apparent SO2 and oxygen partial pressure was a sigmoid curve resembling the haemoglobin oxygen dissociation curve. The Hb index and the apparent SO2 were monitored continuously by tissue reflectance spectrophotometry during the induction of experimental periodontitis with silk ligatures. The Hb index increased rapidly during the first 7 days after ligation and then decreased gradually during the remaining period. The apparent SO2 decreased during the first 7 days but gradually rose during the final 9 weeks. The maximum level of the deoxyhaemoglobin concentration after ligation was elevated about two times over that found before ligation, whereas the increase in oxyhaemoglobin concentration was relatively small. These results suggest that the oxygen supply to inflamed gingiva may increase to some extent, but not sufficiently to compensate for the increased oxygen consumption.