The benefits of a school-based plaque removal program are presented. Children in grades 5-8 were inclined in a study which was designed to determine the effect on oral hygiene, gingival inflammation and dental caries of removing dental plaque through supervised daily flossing and toothbrushing in school. A fluoride-free dentifrice was used. Controls did not receive instruction in plaque removal procedures nor did they engage in plaque removal activities at school. For three school years the students in the treatment group practiced daily plaque removal, supervised by trained personnel. All participants were examined initially for plaque (PHP), gingival inflammation (DHC) and dental caries (DMFS). Girls in the treatment group showed a significant reduction (28%) in mean plaque scores and, for girls and boys, the mean changes in gingivitis scores were significantly reduced (40% and 17%, respectively). Adjusted mean incremental DMF surface scores were 13% lower in the treatment group than in the control group. The difference between groups was not statistically significant and was accounted for entirely by the findings in mesial and distal surfaces (26%). This difference approached statistical significance (P=0.07).

After two school years of a supervised daily plaque-removal program in school, children in the treatment group showed a significant reduction in plaque and gingival inflammation scores compared with children in the control group. However, differences between groups in terms of plaque and gingivitis scores virtually disappeared during the summer vacation. The increment of dental caries was lower in the treatment group than in the control group, but the reduction, which averaged about 20 percent, was not statistically significant either for teeth or for surfaces. Although the 24-month findings of the present study indicate some degree of success in reducing plaque and gingivitis and a marginal effect in reducing the incidence of dental caries among children who engaged in daily, supervised plaque-removal in school, obvious drawbacks limit the value of this regimen.

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A series of alpha,alpha'-bis[3-(N,N-dialkylcarbamoyl)piperidino]-p- xylenes were synthesized and tested for their inhibitory activity on ADP-induced aggregation of human platelets. A parabolic curve was obtained when log 1/C (activity) was plotted against log P (octanol/water partition coefficient). Using this as a model, a new analogue, alpha,alpha'-bis-[3-(N-methyl-N-butylcarbamoyl)piperidino]-p-xylen e (3g), was synthesized with a predicted IC50 of 25 microM. When this compound was subsequently evaluated, the IC50 was 22.1 +/- 5.5 microM, demonstrating the applicability of this model. The amide oxygen of the carbamoyl substituent appeared necessary for activity. Thus, for example, when the amide carbonyl group of 3a (IC50 = 44.5 microM) was reduced to CH2, the resulting compound 4 had a dramatically reduced activity, IC50 = 1565 microM. Compound 3a was resolved into (+) and (-) enantiomers and a meso (0) diastereomer using fractional crystallization, diastereomeric tartrate formation, and chiral HPLC. Compared to (-)-3a, the (+) isomer was 15 times more potent when ADP was the agonist and 19 times more active when collagen was used as the agonist. Molecular modeling of R,R- and S,S-3a using the SYBYL program was used to examine their interactions with phosphatidylinositol (PI). There was a better fit between PI and the R,R-3a with the energy of interaction being 17.6 kcal/mol less than that of the S,S-3a/PI complex. Although the absolute stereochemistry of individual enantiomers is not known, this study shows that R,R-3a interacts more favorably with PI than does S,S-3a and that (+)-3a is a more potent inhibitor of human platelet aggregation than (-)-3a. It is postulated that because of their lipophilicity, these compounds penetrate the platelet membrane and are then protonated at the pH of the cytosol. The protonated N then neutralizes the anionic charge on the membrane phosphoinositides, thereby rendering them less susceptible to hydrolysis by phospholipase C. Thus, the determinant parameters for optimum antiplatelet activity in 3-carbamoylpiperidines are (1) the amide carbonyl, (2) appropriate stereochemistry of the 3-substituent and (3) a log P value of about 4.5.

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