Individual variations in protective effects of experimentally formed salivary pellicles

Salivary proteins protect teeth against acid-induced softening and demineralization by forming a pellicle. However, little is known about individual, gender and ethnic variations in this effect. Therefore, we aimed to determine differences in protective effects of experimentally formed pellicles from 10 healthy young Scandinavians (3 women and 7 men) and 10 healthy young non-Scandinavians (4 women and 6 men) including Arabic, Persian, Pakistan, Indian, and Chinese subjects. Bovine enamel blocks, which were precoated with parotid and submandibular salivary proteins for 12 h, were exposed to an acidic solution with surface microhardness (SMH) determinations before and after. No change in SMH equalled 100% protection, whereas SMH corresponding to no protein coating equalled 0%. The results showed that experimentally formed pellicles from non-Scandinavians protected enamel better than pellicles from Scandinavians (p < 0.001). Within groups protective effects of pellicles formed from parotid and submandibular saliva were equal and subjects with high protection from parotid saliva pellicles also had high protection from submandibular saliva pellicles (r = 0.78; p < 0.001). Within groups considerable differences were obtained among individuals ranging from 25 to 51% protection. However, SDS-PAGE and HPLC did not reveal any systematic relation between saliva protein composition and protective effects, although slightly more of the SN-isoform of S-type cystatin was found in pooled parotid saliva from those non-Scandinavian subjects showing highest protection. We conclude that individual variations in experimental pellicle protection against erosive challenges exist and that such variations appear not to be due to differences in a single protein component.