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.

Optimal Drinking Water Composition for Caries Control in Populations

Apart from the well-documented effect of fluoride in drinking water on dental caries, little is known about other chemical effects. Since other ions in drinking water may also theoretically influence caries, as well as binding of fluoride in the oral environment, we hypothesized that the effect of drinking water on caries may not be limited to fluoride only. Among 22 standard chemical variables, including 15 ions and trace elements as well as gases, organic compounds, and physical measures, iterative search and testing identified that calcium and fluoride together explained 45% of the variations in the numbers of decayed, filled, and missing tooth surfaces (DMF-S) among 52,057 15-year-old schoolchildren in 249 Danish municipalities. Both ions had reducing effects on DMF-S independently of each other, and could be used in combination for the design of optimal drinking water for caries control in populations.

Oxidation of uric acid. 4. Synthesis, structure, and diabetogenic action of 5-imino-2,4,6(1H,3H,5H)-pyrimidinetrione salts and their alloxan-like covalent adducts

Three synthetic routes to salts of 5-amino-5-hydroxy-2,4,6(1H,3H,5H)-pyrimidinetrione (10) are described. The key reactions involved acid-catalyzed cleavage of 5-amino-5-ureido-2,4,6(1H,3H,5H)-pyrimidinetrione (7), conversion of uramil (8) to dehydrouramil (9) and subsequent hydration, and the condensation of alloxan (5) with ammonium salts. The carbinol ammonium salt structure 10a was unambiguously established by X-ray crystallography. New alloxan-like compounds 7, 9, and 10 were evaluated for diabetogenic activity in rats. Compound 7 was inactive, whereas compounds 9 and 10 showed the highest activity comparable to that of streptozotocin (12).