In Vivo Capillary Loop Hemoglobin Spectroscopy in Labial, Sublingual, and Periodontal Tissues

Reproducible estimates of hemoglobin absorption spectra from human capillaroscopy images of arterioles, capillaries, and venules in sublingual and labial mucosa in vivo and venules in the tissues lining the periodontal pocket.

By reducing the size of both the imaging lens and the light guide to a maximum 1 mm diameter and opposing them with a gap of 600 μm we have been able to transmit light through the loop of tissues which moves into the gap between the lens and light guide when these are placed in contact with the labial and sublingual oral mucosa. This allows in vivo transillumination of the microvessels supplying the mucosa.

Images from five volunteers showed similar patterns and the ratio of optical densities at 410 nm and 430 nm had a range from 2.5 at 90-100% saturation to 0.5 at zero % saturation. Measured optical density ratios ranged from 0.5 to 1.6 ± 0.1 in the afferent arm of the capillary loops and 0.5 to 1.1 ± 0.1 in the efferent arm of the capillary loops.

In vivo spectroscopic hemoglobin optical density ratios in oral mucosal microvessels show a qualitatively consistent result within the expected in vitro parameters.