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Biomedical subjects

J Ekstrand

Publications and source records attributed to J Ekstrand.

At least 109 records · Page 6Linked to original sources
PubMed1987

Physiological factors influencing salivary clearance of sugar and fluoride.

The salivary clearance of sugar and fluoride is influenced by several physiological factors not yet fully investigated or understood. There are reasons to believe that these factors influence both the acid production by sugar fermentation in the dental plaque and the cariostatic action of fluoride on the enamel surface and its immediate environment. This paper presents theoretical and experimental considerations of physiological factors which influence the kinetics of sugar and fluoride in the oral cavity.

Fluorides↗
PubMed1987

Pharmacokinetic aspects of topical fluorides.

Pharmacokinetic studies have revealed quantitative information about the bioavailability, rate of absorption, distribution, and clearance of fluoride following the use of fluoride-containing dentifrices, gels, varnishes, and solutions. It is concluded that following the use of topical fluoride products, variable amounts of fluoride are swallowed and absorbed into the systemic circulation--amounts which may be sufficient to produce acute or chronic side-effects. Pharmacokinetic data should, therefore, form part of the basis for the optimal and safe use of fluoride products. In addition, there is a need for future research to determine the kinetics of fluoride in the oral fluids after the application of topical fluoride agents and to determine the associated changes in the composition of the mineral components of the oral fluids.

Acidulated Phosphate Fluoride↗
PubMed1986

Occupational fluoride exposure and plasma fluoride levels in man.

The individual fluoride exposure and the corresponding body fluid levels were studied in 41 workers in an aluminum plant in Sweden. During the shift (8 h) personal air samplings were performed and plasma fluoride levels determined. Pre- and post-shift urine fluoride excretion were also measured. The average total fluoride exposure was 0.91 mg/m3 of which 34% was gaseous fluoride (mean value 0.31 mg/m3). The mean fluoride plasma level before the shift was 23 ng/ml (1.2 microM/l) and increased on average to 48 ng/ml (range 14-151 ng/ml) at the end of the shift. The plasma levels found were in no case remarkably high. There was a high correlation between fluoride renal clearance and urinary flow (r = 0.481; n = 38; P = 0.00232). A high fluid intake during the shift will thus increase the capacity of the kidney to excrete fluoride and decrease the levels of fluoride in the body. There was a significant correlation between the amount of gaseous fluoride and the area under the plasma concentration-time curve (r = 0.459; n = 40; P = 0.0029) and also the amount of fluoride excreted (r = 0.530; n = 40; P = 0.0004). When fluoride exposure and body burden are to be studied on an individual basis these two parameters give better quantitative information and are to be recommended instead of urine fluoride concentration measurements. The prevention of fluoride inhalation by using a safety-mask during the shift was also demonstrated. The workers who used a safety-mask during the whole shift reduced the inhalation of fluoride to 30 to 40% compared to those who did not use any mask.

Adult↗
PubMed1986

Isokinetic torque levels for knee extensors and knee flexors in soccer players.

The knee extensor and knee flexor strengths were measured isokinetically (30 degrees, 180 degrees/s) and isometrically with a Cybex II device in three groups of male soccer players (national team players, n = 13; division I, n = 15; division IV, n = 180) and a group of nonsoccer players (n = 32). There were difference in strength between soccer players and nonsoccer players and between players from different divisions. Correction for body surface area did not affect the results. The knee flexor/knee extensor ratio (H/Q ratio) was significantly higher for soccer players than for nonsoccer players. The fast-speed/slow-speed ratio for knee extensors was higher for nonsoccer players and for national team players than for players from divisions I and IV.

Biomechanical Phenomena↗
PubMed1986

Overuse and distorsion soccer injuries related to the player's estimated maximal aerobic work capacity.

Fourty senior male soccer players were selected for this study. Before the season, each subject performed an exercise test, and the maximal capacity of oxygen uptake was estimated according to Astrand and Rhyming. The exercise test was repeated in 25 subjects 6 months later. The subjects were then ranked according to their estimated maximal capacity of oxygen uptake (estimated VO2 max) at the first test and allocated into one of three groups of similar size. During the season, all new injuries were examined and registered by an orthopaedic surgeon, and the subjects were allocated into one of three groups (overuse injuries, distorsion injuries, and other injuries). There were significantly more overuse injuries among subjects with high estimated VO2 max, and the incidence of distorsion injuries tended to be lower among subjects with high estimated VO2 max. No correlation was found regarding the total incidence of injuries and estimated VO2 max. No significant difference in estimated VO2 max was registered between the tests before and after the season.

Athletic Injuries↗
PubMed1986

Occurrence of athletic injuries in voluntary participants in a 1-year extensive newspaper exercise campaign.

In 1977 the newspaper Ostgötacorrespondenten (Corren) started a 1-year campaign for better health. The campaign was called "Piggare med Corren" (get fit with the Corren) and included antismoking, dietary, and exercise components. It was given widespread publicity in the newspaper. The purpose of the study was to examine the extent of self-reported exercise injuries in volunteers who diligently participated in a newspaper campaign. Information was collected from questionnaires sent to the most persistent participants after the campaign; 60% answered the questionnaire. An analysis of the dropouts showed that they had not started to exercise to the same extent as the others. Only 5% said that they had not exercised before the campaign; 6.7% reported that they were injured in connection with their exercising during the campaign in such a way that they had to interrupt their exercise. Thirty-seven persons had called a doctor and 19 persons were reported sick during for an average of 1 month because of the exercise injuries. There were significantly more regular exercisers who had been highly active before the campaign among those who had been injured compared with those who were not injured.

Adult↗
PubMed1986

High doses of fluoride do not affect cyclic AMP levels in human and rat plasma or urine.

The effect of fluoride ingestion on plasma and urinary cyclic AMP levels was studied in healthy volunteers, children undergoing prophylactic fluoride treatment and in rats. In the first series of experiments fluoride ingestion led to a 20-fold increase in plasma fluoride concentration, which was unrelated to changes in plasma cyclic AMP. The only significant effect on plasma cyclic AMP occurred prior to fluoride, an effect attributed to stress. In the second series performed in children increases in urinary F- of up to 200-fold were associated with slight but nonsignificant changes in cyclic AMP excretion. In rat experiments the blood sampling procedure was associated with a rise in plasma cyclic AMP. When this was prevented by pretreatment with propranolol (3 mg/kg), the effect of fluoride (50 ppm in the drinking water) was tested. A fall in urine production was not associated with any change in cyclic AMP excretion or in nephrogenic cyclic AMP. It is concluded that if fluoride alters cyclic AMP in rats and man the effect is small and easily masked by other factors such as catecholamine release following stress.

Adult↗
PubMed1985

Strength and creep of dental amalgam: the effects of deviation from recommended preparation procedure.

The effects of deviations from recommended preparation procedures on the compressive strength, modulus of elasticity, plastic deformation, toughness, and creep of four commercial amalgam alloys have been investigated. Deviations included changes in trituration time, mercury/alloy ratio, and condensation pressure. With regard to both compressive strength and creep, there were great differences in the susceptibility of different amalgam alloys to variations in manipulation. One conventional alloy showed almost no variation in compressive strength as a result of the deviations from the recommended preparation procedure. This material also showed much greater plastic deformation and fracture toughness than the other materials, making it less brittle and probably more resistant to bending forces. Dispersalloy exhibited both increased and decreased strength as a result of the deviations, while ANA 2000 and Revalloy only showed decreased strength. Some of the alterations for ANA 2000 and Revalloy resulted in a decrease in strength below an acceptable clinical level. Regarding the modulus of elasticity, only the conventional alloys were affected by the alterations in the preparation procedure. However, for the plastic deformation, the results were reversed; only the high-copper alloys were affected. The toughness of the specimens was decreased for all the alloys with the exception of one, which was insensitive to changes in the preparation procedure as far as compressive strength was concerned. One of the high-copper alloys showed the least change in creep relative to deviations in preparation procedures. Lowered condensation pressure increased the creep value for all the amalgams; and for the conventional alloys a lowered mercury/alloy ratio also resulted in increased creep.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗
PubMed1985

Influence of variations in preparation of dental amalgam on dimensional stability and porosities.

The susceptibility of amalgam to deviations in the preparation procedure produced an overall trend for both the setting dimensional stability and the number of porosities. The dimensional stability of ANA 2000 was the least affected by the deviations, while ANA 68 exhibited low susceptibility to the deviations when porosities are concerned. Lowered condensation pressure usually increased both the setting expansion and the number of porosities, and vice versa. Dispersalloy exhibited an increased number of porosities with both higher and lower condensation pressure. Except for ANA 2000, undertrituration caused increased expansion and porosities, while overtrituration resulted in increased contraction but minor effects on porosities. Lower mercury/alloy ratio increased the setting expansion and the number of porosities, while the response to a higher ratio was relatively small with the exception of a markedly increased setting expansion for ANA 68.

Chemical Phenomena↗
PubMed1985

Exercises for knee flexors and extensors in uninjured soccer players: effects of two different programs.

The effects of two 4-week training programs on knee flexor and extensor strength were measured isokinetically (angular velocity 30 degrees, 180 degrees/s) and isometrically in division IV soccer players. Group A followed a team training program and group B an individual weight training program. Group C served as controls. Muscle strength was not increased by soccer training alone, but was increased by the individual training program, which resulted in significantly better knee extensor strength than did the team training program.

Adult↗
PubMed1985

Plasma fluoride and bromide concentrations during occupational exposure to enflurane or halothane.

The plasma fluoride and bromide concentrations were studied in operating theatre personnel. When enflurane was used, the increase in plasma fluoride concentration could not be distinguished from normal individual variations, but the plasma bromide concentration increased significantly when halothane was used. Seven patients were exposed to enflurane in a concentration of 200 parts per million for 4 h. A significant increase in the plasma concentration of fluoride was observed. The peak concentrations of fluoride occurred during exposure and the increase lasted less than 12 h. The increase in fluoride concentration was larger at this trace concentration than reported after anaesthetic concentrations. Cerebrospinal fluid (CSF) fluoride concentration was also studied; a smaller and delayed increase was found in CSF compared to plasma.

Air Pollutants, Occupational↗
PubMed1985

Fluoride release from a fluoride-containing amalgam in vivo.

Six test subjects using a low fluoride diet collected saliva samples each morning for 1 wk to determine the normal fluoride concentration. During the following 8 wk an acrylic plate, containing amalgam "fillings" corresponding to 6 MOD amalgams in premolars, was worn each night. Saliva samples were collected every morning and analyzed with a fluoride-ion electrode. Normal fluoride values ranged from 1.22 microM to 0.57 microM. The first days after insertion of the plates the fluoride concentration ranged from 91.06 microM to 12.26 microM in the subjects. The following 25-30 days there was an exponential decline of the fluoride concentration in saliva with a half-life of 6 to 7 days. The fluoride level was significantly higher (P less than 0.01) than basal levels in all subjects during this period. The following 20-25 days the fluoride level decreased more slowly, approaching the basal level. One subject had a significantly higher fluoride level for all 8 wk. Since the saliva fluoride concentrations registered seem to be sufficient to enhance remineralization, it is concluded that restorations with this material may have a favorable effect not only on secondary caries, but on any initial demineralization in the mouth.

Dental Amalgam↗
PubMed1985

Effect of repeated intake of a sugar free fluoride-containing chewing gum on acidogenicity and microbial composition of dental plaque.

In a double blind cross-over study, 20 subjects were given either a sugar free chewing gum containing 0.25 mg fluoride or the same chewing gum without fluoride, eight times a day for 7 days. The pH of 3-day-old plaque was determined before and after each experimental period following a 30-s mouth-rinse with 10 ml 15% sucrose. The pH-decrease was significantly less pronounced after using the fluoride gum than after the placebo gum (P less than 0.001). In a second study, 20 subjects participated in a similar study. In this experiment the acid production activity from sucrose in dental plaque in vitro was determined with the aid of a titration method. In addition, the dental plaque wet weight and the total number of cultivable organisms, Streptococcus mutans and lactobacilli, expressed as the number of colonies per mg plaque, were determined. No significant effect was found on any of these parameters after using the fluoride gum compared to the placebo gum. Thus, the results indicate that slightly elevated levels of fluoride in saliva during daytime, achieved by repeated intake of fluoride gums for 7 days, are sufficient to influence the acidogenicity of dental plaque in vivo.

Chewing Gum↗
PubMed1985

Plasma fluoride levels in man following intake of SnF2 in solution or toothpaste.

The degree and rate of fluoride absorption in five volunteers were studied after ingestion of SnF2 and NaF solutions or SnF2 toothpaste. The fluoride concentration in plasma was followed for eight hours. The relative bio-availability of fluoride was calculated and was similar for both the NaF and SnF2 solutions, although the latter solution showed a somewhat faster absorption rate. The bio-availability of fluoride from the SnF2 dentifrice was 85%.

Absorption↗