Atomic force microscopy study of salivary pellicles formed on enamel and glass in vivo

Abstract

This study was performed to evaluate the use of atomic force microscopy (AFM) in examining the surface of the adsorbed layer of salivary proteins (salivary pellicle) formed in vivo on dental enamel and glass surfaces. Enamel and glass test pieces were attached to the buccal surfaces of the upper first molar teeth in two adults using removable intraoral splints. The splints were carried intraorally over periods ranging from 10 min to1 h. Using the contact mode of AFM, pellicle structures could be recognised on intraorally exposed specimens compared to nonexposed enamel and glass surfaces. The surface of the adsorbed salivary pellicle was characterised by a dense globular appearance. The diameter of the globulelike protein aggregates adsorbed onto enamel and glass varied between 80 and 200 nm and 80 and 150 nm, respectively. The structure of the adsorbed protein layer was clearly visible on glass surfaces, even though minor differences in the protein layer between glass and enamel specimens were observed. This study indicates that AFM is a powerful tool for high-resolution examination of the salivary pellicle surface structure in its native (hydrated) state. AFM avoids artefacts due to fixing, dehydration and sputter-coating which occur with scanning electron microscopic analyses.