Helvetica odontologica acta最新文献

Stimulated mixed saliva and interproximal plaque were exposed to the ketohexose sorbose. The average pH of an in vitro 1%-sorbose/saliva mixture increased with time when compared with a highly significant pH-decrease of a sucrose/saliva mixture. In contrast to sucrose rinses, the telemetrically recorded pH of interproximal plaque did not drop below pH 5.5 during and subsequent to rinsing with sorbose solutions.

Simultaneous telemetry of salivary fluoride and of interproximal plaqua pH at the entrance to an interproximal space was used to investigate the effects of sucrose-containing fluoride tablets dissolving in the vicinity of the fluoride and pH sensors. The dissolving of 1.0 mg fluoride-42 mg sucrose tablets caused only slight pH depressions ranging between 6.7 and 6.0 with concurrent increases in salivary F to as high as 190 ppm. Acid formation in interproximal plaque by fluoride-free, sucrose-containing placebo tablets decreased pH to 4.2.

Mixed saliva stimulated by mastication was sampled under standardized conditions in 50 recruits before and after a 10-day period of intensified oral hygiene. The degree of gingivitis was assessed (1) with the Sulcus Bleeding Index and (2) with the spectrophotometric determination of blood iron in the saliva samples. Oral hygiene reduced (1) the SBI from 1.1+/-0.6 to 0.6+/-0.4 and (2) salivary iron from 0.6+/-0.5 to 0.3+/-0.4 mug, both differences being highly significant (PF is less than 0.001). SBI and iron data were significantly but not strongly correlated (r=51).

Unitary EMG activities in masseter muscle of decerebrate cats were recorded during repetitive stimulation (20-50 Hz) of the lingual nerve and during vibration. These two kinds of stimuli facilitated EMG activities, whereby their effects could summate. Masseteric EMG response was also obtained during jaw opening phase of the cyclic jaw movement. With the jaw cyclically moved at a widely opened position: motor units discharged even at the jaw closing phase during simultaneous lingual nerve stimulation or during vibration. Based on the results obtained, two possible pathways for lingually induced excitation of masseteric EMG can be speculated on: an excitatory pathway from the lingual nerve to the masseteric motoneurons, secondly a direct pathway to masseteric motoneurons. As facilitation of masseteric EMG was obtained with the threshold lower than that of jaw opening reflex, separate afferent fibers concerning these two reflexes should also be considered.

16 dental students rinsed daily with a placebo solution, Taurolin 2% (formaldehyde releasing antimicrobial), Vantocil 0.1% (polybiguanide), and with amine fluoride 0.025%. Depression of plaque growth assess with the Sulcular Plaque Index was 50.6, 40.2 and 21.5%, respectively.

In a first 2-day experiment, inhibitions of plaque formation by 0.05% Hibitane and Vantocil rinses were similar. In a second 7-day test, the same 2 antimicrobials again showed similar degrees of plaque depression. The Vantocil group exhibited significantly more severe tooth surface staining than the Hibitane group.

3 different enamel biopsy methods were tested on 2 maxillary permanent incisors on each of 90 schoolchildren. In methods A and B the round biopsy field was bordered by copalite varnish, while method C utilized a scotch tape border. The biopsy itself resulted from etching the enamel surface with 2N perchloric acid for 7 sec for method A, and 14 sec for methods B and C. Flouride was measured with the fluoride activity electrode. The doubled etching time caused only a 30 to 40% increase of enamel removal. Method C showed the best reproducibility.

180 fluoride biopsies were taken in 30 children from the labial surfaces of the 6 maxillary anterior teeth. The average thickness of the biopsied surface enamel was 8.35+/-0.75 mjm. Intact, not treated enamel had an average F-content of the integral of 550 ppm. 7 days after one 3-min topical application of amine fluoride on intact enamel the average F-concentration was the integral of 1150 ppm. 7 days after one amine fluoride application on enamel previously etched with pyruvic or orthophosphoric acid, the average F-content was the integral of 3400 ppm and the integral of 2800 ppm respectively.

The effects of the supplementation of equal amounts of fluoride given at different frequencies on caries inhibition and on fluoride uptake and retention by the molar surfaces were investigated in 3 rat caries tests. In the first experiment fluoride was supplemented to the drinking water, in the second it was incorporated in the cariogenic diet and in the third it was applied topically. In the first caries test fluoride was administered in the drinking water either continuously at concentrations of 20, 40 and 60 ppm F or at the double concentrations of 40, 80 and 120 ppm F every second day for 10 days prior to a cariogenic period of 21 days. At the end of the 10-day fluoride administration period the fluoride concentration in the molar surfaces (F-M) were closely correlated to the fluoride concentrations of the drinking solutions and to the intake by the animals. The molar surface disolution rates (S-M) were significantly lower in all fluoride groups than in the control groups but were not correlated to the F-M. At the end of the subsequent 21-day cariogenic period the S-M were not significantly lower in the fluoride than in the control groups. The F-M, significantly higher in the fluoride than in the control groups, were in the former groups not significantly different from each other. Irrespectively of the fluoride administration schedule, the caries incidences were equally lower in all fluoride groups than in the control groups. In the second caries test NaF and Na2PO2F were incorporated in the cariogenic diet and given to the rats at the same daily dose but at frequencies of 12, 18 and 36 times. The concentrations tested were 225, 150 and 75 ppm F. There were no significant differences between NaF and Na2PO3F in caries inhibitions, F-M and S-M. The frequency of fluoride administration had no significant effects on the parameters investigated. In the third caries test NaF and Na2PO3F were applied topically once, twice or thrice daily during a 20-day cariogenic period at concentrations of 4500, 2250 and 1500 ppm F respectively. While NaF and Na2PO3F were equally effective in inhibiting caries, NaF was more effective than Na2PO3F in enriching the F-M and in reducing S-M. Again the frequency of fluoride application had no significant effects. Because of the lack of influence of the frequency of fluoride supplementation on caries inhibition and the lack of correlation between caries reductions and F-M and S-M it was concluded from the caries tests that in the rat the interference of fluoride with the bacterial metabolism through its continous presence at the plaque-enamel interface rather than the reduction of enamel solubility and the promotion of enamel remineralization seems to be its most important cariostatic mechanism. A second series of experiments investigated the effects of the daily intragastric administration to pregnant rats of either 3.5 mg F once daily or 1...

Fluoride retention from fluoride rinses (250 ppm F), calculated from F-concentrations and volumes of expectorates, and fluoride clearance, determined in whole saliva samples collected 1, 5 and 10 minutes after rinsing, were studied in 70 adults. F-retention from a 1:1 oleylamine-cetylaminefluoride rinsing solution (15 ml. 15 sec) was 410 mjg F, from a sodium fluoride rinse 343 mug F. 563 mug F were retained from a 30-sec amine fluoride rinse. Fluoride clearance was significantly slower after cetylaminefluoride rinses than after NaF rinses. Prerinsing with sodium lauryl sulfate or cetylaminechloride annihilated the F clearance superiority of cetylaminefluoride over NaF.