Comparative clinical wettability of teeth and intraoral mucosa

The observed reduced adhesiveness of human intraoral mucosa, as compared with adjacent teeth, was determined for 14 healthy humans to correlate with differing measured intraoral contact angles for a variety of otherwise non-interacting test liquids on these two equally water-wettable surfaces under clinical conditions. Measurements were made on the front maxillary tooth surfaces and the-inner lower lip mucosal surfaces of the same subjects, either immediately upon first exposure of the oral tissues or after 30-60 s drying in ambient air. Lower critical surface tensions were found for wet mucosal surfaces (25.4 mN/m) than for wet tooth surfaces (31.2 mN/m). Exposure to air for up to 1 min increased the mucosal critical surface tensions by only 2 mN/m, and had even less influence on the measured properties of tooth surfaces. These data suggest that the observed 'bioabhesive' surface quality of oral mucosa, retaining negligible plaque, is associated with its critical surface tension in the zone near 25 mN/m, as found earlier for the natural fouling-resistant surfaces of dolphins and killer whales.