Characteristics of an in vitro dental pellicle.

Procedures developed for in vitro pellicle formation in intact enamel proved useful for relating qualitiative characteristics of dental pellicle to a number of factors. Coronal surfaces of extracted human molars from experimental and control groups were pumiced, sterilized, and incubated for two hours at 37 C in parotid saliva and distilled water, respectively. Pellicle proteins were desorbed sequentially with water and 0.2 M sodium phosphate, with a pH of 7.0. Polyacrylamide disc electrophoresis of the desorbates yielded distinct patterns, indicating selective adsorption of proteins from saliva, varying affinity to enamel, and the presence of proteins not acquired in vitro from saliva. Certain pellicle components, including amylase and IgA, showed a relatively weak affinity for enamel and were eluted in part by water; other proteins were desorbed only by phosphate buffer. Anionic electropherograms of the phosphate desorbates showed an increase in the two most anodic proteins relative to corresponding salivary bands. An intense anodic protein and two minor bands were eluted by water or buffer from the surface of control as well as experimental teeth but not from teeth coated with sealants. Serum albumin and alkaline phosphatase were identified as components of the extra-salivary material. Further investigation of the sources and functions of the constituents of the protein layer generally considered as "acquired" dental pellicle appears warranted.