Biomedical subjects

F Lagerlöf

Publications and source records attributed to F Lagerlöf.

At least 19 recordsLinked to original sources

PubMed2004

Influence of the time of measurement of unstimulated human whole saliva on the diagnosis of hyposalivation.

OBJECTIVE: An unstimulated whole saliva flow rate (UWSFR) of less than 0.1 mL/min is often related to symptoms of dry mouth. It is also used as a diagnostic criterion for Sjogren's syndrome, and for assessment of hyposalivation as a caries risk factor. The main hypothesis was that the circadian rhythm of salivary flow affects this diagnosis if saliva is collected at different morning time-points. DESIGN: UWSFR was tested at 7:30 and 11:30 a.m. in 108 individuals, age 15-46 years (mean 33+/-9). The participants were allocated to one of three groups (very low< or =0. 1/min, low 0.1-0.2 mL/min and normal>0.2 mL/min) based on the UWSFR at 7:30 a.m. Different aspects of the perception of oral dryness were rated using Visual Analog Scales. RESULTS: All three groups displayed a statistically significant increase in UWSFR at 11:30 a.m. compared with 7:30 a.m., all of similar magnitude (0.08-0.09 mL/min). In the group with very low UWSFR, 70% at 11:30 a.m. exceeded the 0.1 mL/min limit. There were significant difference in perception of oral dryness between the normal group and both the low and the very low groups. Only the subjects in the groups with a low or very low UWSFR perceived an increase in oral wetness at 11:30 a.m. CONCLUSIONS: It was concluded that the time of measurement strongly influences the diagnosis of hyposalivation. To control the influence of variations in the time of saliva collection, we suggest that unstimulated whole saliva tests are performed at a fixed time-point or in a limited time interval early in the morning.

Adolescent↗

PubMed1998

[Saliva: natural protection against caries].

Salivary secretions protects the teeth and the oral mucosa. The physiology and biochemistry of saliva are discussed in detail. Following functions of saliva such as mechanical protection of teeth and mucosa; antimicrobial properties of saliva, regulation of pH and the role of saliva in de- and remineralisation of dental enamel are reviewed. Salivary gland dysfunction (etiology and treatment) emphasises the item of caries prevention.

Anti-Infective Agents↗

PubMed1996

Effect of citric acid clearance on the saturation with respect to hydroxyapatite in saliva.

Citric acid contained in beverages and foods is one of the main causes of enamel erosion. It was hypothesized that the clearance of citric acid from saliva would influence the degree of salivary saturation with respect to hydroxyapatite (OHAp). Ten subjects rinsed with 2% citric acid, pH 2.1, for 5s. Before and at 1,2, 5, 10 and 15 min after the rinse, a small saliva sample was collected. The sample pH, ionic strength and the concentrations of ionized calcium, inorganic phosphate and citric acid were determined. The pH of the saliva decreased from 7.21 + or - 0.40 (mean + or - SD) at time zero to a minimum of 6.46 + or - 0.88 at 1 min after the rinse. It was back to baseline value after 15 min. The saliva was supersaturated with respect to OHAp at time zero. After the rinse with the citric acid the saturation level shifted to undersaturation in all individuals except one. At 1 and 2 min after the rinse the saliva was, on average, undersaturated. After 5 min the average saturation level was back to supersaturation. The individual differences were large. The correlations between the rate of clearance of citric acid during the 1 minute and the minimum degree of saturation with respect to OHAp at 1,2 and 5 min after the rinse were significant (r 0.84, r 0.76 and r 0.79, respectively). In conclusion, rinsing with citric acid will cause a decrease in the saturation level with respect to OHAp in a highly individual pattern.

Adult↗

PubMed1995

Salivary clearance of citric acid after an oral rinse.

OBJECTIVES: Citric acid clearance from the oral cavity may be an important factor in the erosion of dental enamel. The aim of the present study was to investigate the clearance pattern of citric acid in normal subjects. METHODS: After determination of the unstimulated salivary flow rate and the residual volume of saliva after normal swallowing, 12 subjects rinsed with 95.2 mmol l-1 citric acid for 5 s. At 1, 2, 5, 10 and 15 min after the rinse a small saliva sample was collected and the concentration of citric acid was determined enzymatically. For each subject three separate experiments on different occasions were performed with a citric acid solution of pH 2.1 and one experiment with a solution of pH 4.5. RESULTS: The salivary citric acid concentration declined biphasically: rapidly during the first 2 min, then more slowly. The elimination rate over the first minute was on average 87.7 mmol l-1 min-1 at pH 2.1 compared with 85.0 mmol l-1 min-1 at pH 4.5. The difference between individuals estimated from the areas under the clearance curve was strongly significant (P < 0.001). No significant relation was found neither between salivary flow rate and clearance, nor between residual volume after swallowing and clearance. CONCLUSION: The clearance pattern of citric acid is an individual property.

Adult↗

PubMed1995

Site specificity of citric acid retention after an oral rinse.

Erosion of the buccal incisor enamel, most frequent in the upper jaw, has been associated with excessive oral exposure to citric acid-containing foodstuffs. The aim of the study was to determine the retention of citric acid at different sites in the mouth after a standardized exposure. Thirty-four normal subjects rinsed with 95.2 mmol/l (2%) citric acid, pH 2.1, for 5 s. At 1 min 55 s after the rinse a preweighed cotton pellet was used to collect saliva samples from upper labial incisor surfaces (UB), lower labial incisor surfaces (LB) and sublingually (SL). The citric acid concentration was determined enzymatically. The concentrations were (mean +/- SD): 32.12 +/- 19.50, 11.90 +/- 8.60 and 1.52 +/- 1.90 mmol/l in the saliva collected from the UB, LB and SL sites, respectively. Analysis of variance revealed that the citric acid concentration in the upper incisor site differed significantly from that of the lower incisor site (p < 0.001) and the sublingual site (p < 0.001), and that the lower incisor site differed significantly from the sublingual site (p < 0.001). The individuals differed significantly with respect to citric acid retention (p < 0.05). A significant correlation was found between UB and LB sites (r = 0.61, p < 0.05).

Adult↗

PubMed1994

Oral retention of glucose at pharmacologically reduced salivary flow in man.

The aim was to study the influence of mouthrinses with glucose, at concentrations ranging from 1 to 50%, on oral retention at two different locations in the oral cavity. Salivary secretion was reduced in 10 subjects by injection of methylscopolamine nitrate submucosally. The volunteers were randomly assigned to rinse with 10 ml of either 1%, 10%, or 50% glucose solution for 30 s, after which measurements of glucose concentration and parotid salivary secretion rate were performed during a 10-min period. The results showed higher salivary glucose levels vestibularly than sublingually. The difference in glucose retention between the two locations increased when the salivary flow rate recovered. The relationship between secretion rate and area under the curve for glucose measured sublingually, but not in the vestibule, was bilinear.

Adult↗

PubMed1994

Intra- and inter-individual differences in salivary sucrose clearance over time.

Salivary clearance of sugars influences acid production of dental plaque. The aim of the present study was to follow the clearance of sucrose over time. Ten subjects participated in five or six experiments each during a period of 20 months. The subjects rinsed with a 20% sucrose solution. Before the rinse and after 2, 5, 10 and 30 min a saliva sample was collected. The salivary sucrose concentration was determined by an enzymatic technique. As a measure of the clearance of sucrose in saliva, the area under the concentration versus time curve (AUC) was used. Analysis of variance revealed no differences with time in the intra-individual AUC. However, the differences in AUC among individuals were highly significant (p < 0.001). The results show that the clearance pattern of sucrose may be an individual property which is constant over long time periods.

Acids↗

PubMed1994

Caries-protective factors in saliva.

Saliva influences caries attack mainly by its rate of flow and by its content of fluoride. The salivary flow rate influences to a high degree the rate of oral and salivary clearance of bacterial substrates included in foods and snacks. This influence is site-dependent. The basal salivary fluoride concentration is low, about 1 mumol/L, independent of salivary flow rate, and not influenced by diurnal variation. After an exposure of the oral cavity to fluoride, the increased fluoride level is decreased by a process influenced mainly by the salivary flow rate and the volumes of saliva in the mouth before and after swallowing. Other less important caries-protective factors in saliva include its buffer ability, its content of calcium, inorganic phosphate, pH-increasing substances, and anti-microbial agents.

Cariostatic Agents↗

PubMed1993

Influence of constant fluoride levels in solution on root hard tissue de- and remineralization measured by 125I absorptiometry.

To study the effect of fluoride on de- and remineralization of root hard tissue, an automatic pH-cycling caries model, simulating Stephan curves, was used for 21 days. From each of 13 unexposed human roots, four cementum/dentin blocks were prepared. Four experiments were carried out: one block from each tooth as subjected to pH cycling without and with fluoride at the concentrations of 0.02 ppm (1.0 mumol/l), 0.20 ppm (10.5 mumol/l) and 2.00 ppm (105.3 mumol/l) in the de- and remineralizing solutions, respectively. Mineral change in the specimens was monitored by 125I absorptiometry. When no fluoride was added to the solutions the change in transmission (delta T) increased continuously over 21 days, indicating loss of mineral. In the 0.02-ppm F experiment, there was a marked decrease in delta T, but almost no change in the 0.20-ppm F experiment. pH cycling with 2.00 ppm F in the solutions resulted in a gain of mineral in or most likely on the surface of the cementum/dentin blocks, indicated by a continuously decreasing delta T. The fluoride level in the solution significantly influenced the change in the mineral content of the specimens. Microradiographs of the sectioned blocks showed radiodense surface zones, varying degrees of subsurface demineralization and signs of remineralization or mineral deposition.

Absorptiometry, Photon↗

PubMed1993

Effect of intermittent delivery of fluoride to solution on root hard-tissue de- and remineralization measured by 125I absorptiometry.

The effect of intermittent fluoride levels on root hard-tissue de- and remineralization was studied once daily for 21 days in a pH-cycling caries model with simulated fluoride clearance curves. Four root hard-tissue blocks, from each of 12 human teeth, were cut out parallel to the cementum surface. During a daily 15-hour period, the blocks were subjected 12 times to pH changes similar to those which occur in plaque after a carbohydrate intake. The fluoride was delivered immediately before a daily nine-hour remineralization period. Four experiments were independently carried out: One block from each tooth was subjected to pH-cycling without and with fluoride delivery, simulating a rinse with 0.025, 0.2, and 1.0% sodium fluoride (NaF), respectively. The mineral change in the blocks was monitored by 125I absorptiometry and expressed as the change in transmission (delta T). The surface between the data points (delta T values) and the x axis (time points) was used as a summary measure, i.e., the area under the curve (AUC). When no fluoride was delivered, the delta T increased over 21 days, indicating loss of mineral. The AUC was, on average, 5.85 +/- 0.68 (mean +/- S.E.) %.day. In the 0.025% NaF-rinse experiment, there was a marked reduction in mineral loss, indicated by an average AUC of 1.66 +/- 0.59%.day. In both the 0.2 and 1.0% NaF-rinse experiments, a decrease in delta T, indicating gain of mineral, was observed from day 2. Negative delta T values occurred after 7 and 3 days, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1992

Salivary clearance of sugar before and after insertion of fixed orthodontic appliances.

This study was conducted for the purpose of establishing the possible influence of orthodontic therapy with fixed appliances on salivary clearance of sugar. Fifteen consecutive patients between the ages 12 and 17 years took part in the investigation. Unstimulated salivary flow rate, residual volume of saliva in the mouth after swallowing (RESID), and salivary clearance of sugar was determined on two occasions, before treatment commenced and after a minimum of 3 weeks of appliance wear. Analysis of the data showed that both RESID and salivary flow rate exhibited significantly increased levels during orthodontic therapy. The insertion of fixed appliances did not seem to have any effect on the rate of salivary clearance of sugar. It was assumed that this finding could be a consequence of the combined effects of the changes in salivary flow rate and RESID.

Adolescent↗

PubMed1992

Integrated currents between amalgams and a gold alloy in saline solutions and natural saliva with different chloride content.

The effect of different sodium chloride concentrations on the integrated currents (charge transfers) between dental amalgams and a gold alloy was studied in a bimetallic cell containing saliva or saline solutions. The integrated currents were only to a minor degree affected by increasing chloride concentrations for the high copper amalgams both in saliva and saline solutions. The integrated currents in the experiments involving conventional amalgam were several times higher than those for high copper amalgams. In saline solutions a charge transfer maximum was found at 0.2 M chloride. In saliva an increase of the charge transfer was found with increasing chloride content.

Chlorides↗

PubMed1992

Increased release of tissue plasminogen activator and its inhibitor in human parotid saliva upon stimulation.

Parotid saliva from 12 healthy volunteers was collected prior to and after 5 and 25 min of stimulation at a constant flow rate of 0.25 or 1.0 ml min-1. In the salivary samples the concentrations of tPA (tissue-type plasminogen activator), PAI-1 (plasminogen activator inhibitor type-1), albumin and total protein were determined and the activity of amylase, tPA and PAI assessed. Presence of both tPA and PAI-1 antigen was demonstrated in all samples, and in unstimulated saliva the ratio between the activator and its inhibitor was 1:7. Upon stimulation we found a significantly increased concentration of PAI-1, a less pronounced increase in tPA concentration, unchanged amylase and total protein levels and significantly decreased albumin concentration. tPA activity was significantly reduced after prolonged stimulation which had no effect on PAI activity. In stimulated saliva a significant positive correlation between concentration of tPA and PAI-1 was demonstrated. Stimulation with citric acid had no effect on output of albumin which is passively filtered from blood, whereas the increase in flow rate corresponded to the significantly increased secretion rate of total protein and amylase which is secreted by gland cells. The secretion pattern of tPA and PAI-1 differed significantly from that of albumin in showing markedly increased output rate during the stimulation period, and the relative increase in output of PAI-1 was significantly higher than that of amylase and total protein. Thus, the results from this study suggest an active release of both tPA and its main inhibitor PAI-1 into saliva.

Adult↗

PubMed1991

Ionselective minielectrode determination of ionic and total calcium concentrations in mixed saliva.

A minielectrode suitable for determination of ionized and total calcium in small volumes (5 microliters or less) of biological fluids without loss of carbon dioxide from the sample, was evaluated. The relative standard deviation ranged from 4.5-7.1%, and analytical recovery from 97-101%. Interference by hydrogen, sodium and magnesium was negligible. Small differences in ionic strength between standards and samples caused only minor analytical errors. Freezing the sample prior to analysis significantly affected the readings for ionized calcium concentration. Compared to determination by atomic absorption spectrophotometry, there was no statistical difference in the total calcium concentration of mixed saliva determined by the electrode at approximately pH 4 after addition of a known volume of hydrogen chloride. This minielectrode method evaluated allows accurate calcium analysis of fluids such as secretion from minor salivary glands or the fluid in the dental integument, with subsequent recovery of the sample for further analysis.

Calcium↗

PubMed1991

Relationship between total and ionized calcium concentrations in human whole saliva and dental plaque fluid.

Ionized and total calcium were determined with an ion-selective electrode in unstimulated whole saliva and in simultaneously collected plaque fluid. The mean ionic and total concentrations in saliva from 20 subjects were 0.53 and 1.03 mmol/l respectively, and in plaque fluid 0.64 and 1.20 mmol/l. The total calcium concentration in saliva was closely related to the total calcium concentration in plaque fluid (r = 0.95, p less than 0.001) as was the ionized calcium concentration in saliva to that of plaque fluid (r = 0.84, p less than 0.001).

Adult↗

PubMed1990

The effect of salivary clearance of sucrose and fluoride on human dental plaque acidogenicity.

Ten subjects rinsed with a 20% (0.58 M) sucrose solution with or without 0.2% NaF (905 parts/10(6) F-) added in two separate experiments. Saliva and plaque were collected before rinsing and after 2, 5, 10 and 30 min. Sucrose and fluoride concentrations in saliva and acid anion and fluoride concentrations in plaque were analysed. There was a statistically significant and positive correlation between the concentration of sucrose in the saliva 2 min after the rinse and the subsequent concentrations of lactate in plaque at 10 and 30 min after the rinse with sucrose alone but not in the presence of fluoride. Salivary fluoride concentrations during 2-30 min after the sucrose rinse were significantly correlated with plaque fluoride concentrations during the same time. The addition of fluoride to the sucrose rinse significantly inhibited lactate production.

Acetates↗

PubMed1990

Computer simulation of oral fluoride clearance.

The presence of fluoride in saliva and dental plaque is important for prevention of dental caries. The elimination of fluoride from the oral cavity after introduction of a fluoride containing agent is a complicated physiological process. This process was simulated with a Pascal program running under MS-DOS on IBM-compatible microcomputers. The program calculated the fluoride concentration in saliva as a function of time from several input parameters, the most important being the amount of fluoride, salivary stimulation due to the fluoride vehicle, resting salivary flow rate and volume factors. Furthermore, factors such as excretion of fluoride in the saliva following fluoride absorption in the intestinal tract were modeled. The fluoride concentration in dental plaque due to diffusion was also calculated. Output was directed to files which could be processed by a graphics interface. The results of the computations were very similar to findings in vivo.

Algorithms↗

PubMed1990

Effect of fluoride addition on ionized calcium in salivary sediment and in saliva containing various amounts of solid calcium fluoride.

The aim of the present study was to estimate the fluoride concentrations necessary for the precipitation of calcium fluoride or calcium fluoride-like substances in saliva and salivary sediment, in the presence of various amounts of chemically pure calcium fluoride. Fluoride was added in increments to whole saliva to which solid calcium fluoride had been added. The ionized calcium concentration was determined immediately after centrifugation. In salivary sediments and saliva with no calcium fluoride added the ionized calcium concentration was nearly independent of the fluoride concentration added below 10 and 20 mmol/l, respectively, and at fluoride concentration above 15 and 25 mmol/l, respectively, nearly no ionic calcium was detected. In the presence of calcium fluoride the ionized calcium concentration decreased rapidly with increasing concentrations of fluoride. The more calcium fluoride added, the lower the ionized calcium concentration at a certain fluoride level. The results suggested that in the in vivo-situation, caries preventive measures based on frequent oral exposure to low concentrations of fluoride may provide calcium fluoride or calcium fluoride-like substances, which will serve as a reservoir for fluoride.

Calcium↗