The effect of saliva on the amount of KOH-soluble fluoride formed on a sound enamelsurface after application of amine fluoride solution of varying fluoride concentrations (1, 0.5 and 0.25% F) and pH (5.3, 4.5 and 4.0) was examined in an in vitro study. The saliva pretreatment increased the amount of KOH-soluble fluoride at the highest pH value. For any given fluoride concentration, the presence of saliva did not influence the amount of KOH-soluble fluoride. These data suggest that saliva could enhance the amount of KOH-soluble fluoride if the topical fluoride preparations are not highly acid.

The aim of this in vitro study was to examine whether the concentration of amine fluoride solution influences the uptake of fluoride by enamel after topical treatment. Four slabs were prepared from each of 31 impacted third molars and selected at random so that one slab from each tooth was present in each group. One group of slabs served as an untreated control (D). The slabs of the other three groups were shaken for 3 min in an amine fluoride solution on 3 successive days: group A (1% F), group B (0.5% F) and group C (0.25% F). The amounts of KOH-soluble fluoride produced with 1 and 0.5% amine fluoride solution did not differ significantly and were superior to 0.25% amine fluoride solution. A statistically significant increase in structurally bound fluoride was observed in groups A, B and C compared with control group D. The difference in the amounts of structurally bound fluoride was significant only between 1 and 0.25% F concentrations. These data suggest that the fluoride content in an amine fluoride solution (1%) can be decreased by half without reducing its ability to form alkali-soluble or structurally bound fluoride. The results of this study are consistent with those of previous clinical studies.

The effects of standard topical amine fluoride solution (1% F) and a low-fluoride solution (0.5% F) with two different frequencies of application (5 and 10 times a year) on 2 years dental caries increment were compared in a double-blind clinical trial involving 199 kindergarten children. The results suggest that increased frequency of application of a low fluoride topical solution (10 times a year) may provide caries protection in preschool children with relatively high caries activity.

A double-blind 3-year clinical trial was conducted in a nonfluoridated water community in which 354 schoolchildren aged 9–10 years were assigned randomly to three groups (A, B and C) and subjected to a treatment with 1 of 3 different concentrations of amine fluoride solution every 2 months. Clinical examinations were conducted at baseline and after 1, 2, and 3 years. For group A (positive control) receiving topical applications of amine fluoride solution (1%), the 3-year DMFT and DMFS increments were 4.0+ (SD) 2.7 and 8.5 ± 5.6, respectively. For group B (0.5% F), the DMFT and DMFS increments were 4.4 ± 3.0 and 8.4 ± 5.7, respectively; these differences being statistically not significant. The mean caries increments in group C (0.25% F) were 5.1 ± 2.9 for DMFT and 10.0+5.5 for DMFS. The differences in incremental caries scores between group C and groups A or B were statistically significant (p < 0.05). Thus, the amine fluoride solution, in which the fluoride content was reduced by half, provided similar caries reductions in schoolchildren as did a standard amine fluoride solution with 1.0% F.

Sm,-Pharmacological examinations of cocaine and desipramine have shown similarities in some of their properties. The essential characteristic common to both drugs is that both inhibit the uptake of noradrenaline and simultaneously potentiate its effect. Yet there are differences in the activity of the two drugs, for while cocaine inhibits the uptake of noradrenaline to a lesser degree than desipramine (Iversen, 1965) it increases more powerfully the activity of exogenously applied noradrenaline. Taking into consideration these common properties we have examined whether any parallelism exists in the effect of two drugs upon bronchospasm in guinea-pigs. We consider this technique appropriate since adrenergic substances block more or less intensively the bronchial spasm provoked by some spasmogens. The investigation of the influence on the bronchospasm was by plethysmography combined with artificial respiration while the thoracic muscles were relaxed by intravenous injection of suxamethonium in doses of 0.1-0.2 mg/kg (GjuriS, 1965). The animals were anaesthetized with urethane 1.5 g/kg S.C.The effect of cocaine and desipramine was tested in bronchial spasm provoked by 5-hydroxytryptamine (5-m), beginning the experiments at the time when the registered reaction to the spasmogen was 50 % of the initial values (5-HT was given in doses 10-20 g/kg, i.v.). Cocaine, which resembles desipramine in some ways, differs completely in its influence on bronchospasm under these conditions. Thus cocaine in doses of 0.09,0.2 and 5 mg/kg, i.v. increased bronchospasm by 3 1,73 and 93% respectively. On the other hand desipramine inhibited bronchospasm in doses of 1, 5 and 10 mg /kg, i.v. by 11, 48 and 98% respectively. In contrast to our experiments, Foster (1964) found that cocaine potentiated the relaxant effect provoked by transmural stimulation of the trachea at doses less than 25 pg/ml. The two experiments differ in essential ways ; we induced bronchospasm with 5-m in the intact animal whereas Foster stimulated the isolated trachea electrically. The nervous pathways involved may differ.