N. Vassilakos et al., REFLECTOMETRY - A NEW METHOD FOR QUANTITATIVE-DETERMINATIONS OF INTRAORAL FILM FORMATION, Scandinavian Journal of Dental Research, 101(5), 1993, pp. 339-343
A simple optical method - reflectometry - is described to determine th
e thickness and mass of salivary films formed on solid surfaces at ora
l exposure. Reflectometry is based on the fact that p-polarized light
is reflected with minimum intensity at an interface when the angle of
incidence equals the so-called pseudo-Brewster angle. Hydrophilic and
hydrophobized silica surfaces were used as substrates and the reflecto
meter was calibrated against a null ellipsometer. A linear relation wa
s found between the square of the ellipsometrically measured thickness
of silicon oxides on silicon substrates and the reflectometrically re
gistered intensity of the reflected light at these surfaces. Thirty vo
lunteers participated in the study of the thickness of films formed on
the test substrates at oral exposure. The test silica surfaces were p
ositioned in the vestibular sulcus of each test subject for periods of
1, 5, 15, 30, 60, and 120 min. The results show that films formed on
hydrophobic surfaces leveled-off to a thickness value of 140 angstrom
after 60 min. Films formed on hydrophilic surfaces, however, reached a
plateau value of approximately 100 angstrom after only 300 min. Refle
ctometry seems to be an accurate and valid, yet inexpensive and quick
method for quantitative investigations and thickness measurements of e
arly salivary pellicles in large subject groups.