Protective influence of experimentally formed salivary pellicle on enamel erosion. An in vitro study

The purpose of this study was to evaluate dental erosion in 0.1 and 1.0% citric acid in vitro by several different methods and to assess the protective potential of experimentally formed salivary pellicle (24 h in vitro). Bovine enamel slabs were embedded in epoxy resin and polished. Erosion was performed in citric acid for 1, 5 or 10 min and recorded as microhardness loss, as changes of surface roughness (R(a), R(t) and R(zDIN)) and as calcium release. Additionally, erosive alterations were observed with scanning electron microscopy. Significant microhardness loss on non-pellicle-covered specimens was measured after 1-min exposure to 0.1% citric acid. Microhardness loss was time- and concentration-dependent. Salivary pellicle significantly inhibited both microhardness loss, except after 10-min immersion in 1.0% citric acid, and significantly reduced the increase of surface roughness. There were, however, no significant differences in calcium release between pellicle-covered and non-covered enamel. The results support the general conclusion that salivary pellicle effectively protects enamel surface against short-term erosion in organic acids.