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Biomedical subjects

L G Petersson

Publications and source records attributed to L G Petersson.

69 records · Page 4Linked to original sources
PubMed1977

SIMS study of element concentration profiles in enamel and dentin.

The ion probe technique has been employed for the determination of the concentrations of P, F, Cl, C, Na, K, Mg, Sr, Al, and Si at different depths in human tooth. The applicability of the method depends selectively on the element's position in the periodic table, but may be regarded as good for a wide range of microelements of dental interest.

Dental Enamel↗
PubMed1976

Fluorine gradients in outermost surface enamel after various forms of topical application of fluorides in vivo.

Fluorine gradients were analysed in sound facial enamel of 58 pairs of homologous contralateral premolar teeth. A macroscopic stepwise acid etching technique was used to determine the F-concentration to the depths of 40-200 microns. Usually three successive enamel layers (10, 10, and 20 microns) from enamel surface and inwards were removed. Eight pairs of teeth (control group) which had not been subjected to any form of fluoride treatment in the study, were used to assess the difference between teeth extracted at three-week-interval. The F-gradients were almost identical, with only small differences between the teeth. F-concentrations usually decreased from about 900 ppm within the first 10 microns to about 200 ppm at a depth of 40-50 microns. In ten experimental groups (5 pairs of teeth in each group) the F-uptake was studied after various forms of topical application. Contralateral teeth served as control teeth. The highest F-uptake was observed when a fluoride varnish, Duraphat (5% NaF) was applied three times at one weeks' interval. The F-concentrations were about 2000, 900 and 550 ppm, respectively, in the first, second and third enamel layer. The increase in F-concentration in the first enamel layers analysed was significant, but not in the deepest. When testing the effect of paintings procedures with 2% NaF (pH = 7 and 5); 8% SnF2; 5% Na2PO3F; 2% APF-gel (Flura-Gel) in a similar way, a moderate F-uptake was found (100-450 ppm). The uptake of F was limited to the first 10 microns of the enamel. Only 2% NaF (pH = 5) And the APF-gel gave a significant F-uptake within the first layer. Daily mouthwashing procedures during 21 days resulted in insignificant uptake of F when 0.025% and 0.05% NaF solutions were used. Not even rinsing with 0.025% NaF solution for more than 100 days and rinsing with 0.2% NaF solution once a week for three weeks resulted in any significant uptake. The results showed that the F-uptake in vivo from conventional topical application is small and limited to the first few microns of the enamel surface. However, by prolonging the exposure of the enamel surfaces to fluorides in varnishes with high F-concentrations it appears possible to highly raise the F-concentration of the enamel surface and in deeper layers.

Adolescent↗
PubMed1975

Caries preventive effect of a fluoride-containing varnish (Duraphat) after 1 year's study.

The caries prophylactic effect of semi-annual applications of a fluoride-containing varnish (Duraphat) was tested in 121 15-year-old children. The children were divided into a test (60 subjects). The teeth of the children in the test group were coated with fluoride varnish at the beginning of the experimental period and again 6 months later. A clinical and radiographic examination of all children was performed immediately prior to the first application of varnish and 1 year later. The mean caries increment was 0.9 new DMFS in the test group and 4.0 in the control group. The difference was statistically significant at the 0.1% level. The caries prophylactic effect on different tooth surfaces was statistically significant both on proximal and on occlusal surfaces at the 0.1% level. Analyzing the material with respect to the caries prophylactic effect against the background of caries prevalence at the start of the investigation showed a better effect in the group of children with low and medium initial DMFS values.

Adolescent↗
PubMed1975

In vivo fluorine uptake in human enamel following treatment with a varnish containing sodium fluoride.

Fluorine concentrations were determined in three successive enamel layers (approximately 10, 10 and 25 microns in width) of 21 pairs of contralateral teeth, by etching with perchloric acid. The F-concentrations in five untreated pairs of teeth were measured and compared (Group I). A decrease in the F-content from about 1100 ppm in the outer layer to 400 ppm at 40 microns from the enamel surface was found. The differences in F-concentrations between contralateral teeth extracted from the same mouth were small and not statistically significant. In five teeth (Group II) th F-uptake was determined one day after a single topical application of a varnish which contained 5% NaF (Duraphat), and compared with the corresponding control contralateral teeth. A significantly increased concentration of F was observed in all analysed enamel layers of the treated teeth: 3270 +/- 128 (1048 +/- 145), 1520 +/- 97 (596 +/- 61), 567 +/- 52 (296 +/- 14) ppm. Values within brackets denote concentrations in control teeth. In another five teeth (Group III) the fluorine concentration was determined one week after a single application of Duraphat. A significant increase in the F-concentrations in three enamel layers of the test-teeth was found as compared to the control-teeth: 1732 +/- 156 (884 +/- 101), 904 +/- 82 (464 +/- 79) and 524 +/- 88 (296 +/- 24) ppm F. The test-teeth in this group contained less fluorine in the outermost enamel than did the teeth in group II. The difference was significant for the outer two layers. Approximately the same concentration of fluorine was found in test-teeth analysed five weeks after treatment as observed at one week, using same varnish (Group IV). The respective values were: 1795 +/- 410 (907 +/- 216), 749 +/- 135 (369 +/- 90), 382 +/- 88 (166 +/- 40) ppm. The F-increase was significant for all enamel layers analysed.

Adolescent↗
PubMed1975

On topical application of fluorides and its inhibiting effect on caries.

The observations of interest made in this investigation may be summarized as follows: 1. Conventional fluoride application by mouthrinsing with neutral NaF solution (0.025% daily for three weeks or three months; or 0.05% solution daily; or 0.2% solution weekly for three weeks) is found to result in only moderate and insignificant uptake of F in facial enamel surfaces. The gain is in the order of a hundred ppm within 10 to 15 microns' depth (as determined by an acid etching technique) and a few hundred ppm at 0.02 to 0.05 microns (according to pilot ion probe analysis). 2. Painting, at one week's interval for three weeks with 2% NaF (pH=5) solution and application of an APF-gel (Flura-Kerr 1.23% F) results in the significant uptake of a few hundred ppm F within the first 10 microns of the enamel. Painting with 2% NaF (pH=7), with 8% SnF2, or with 5% Na2PO3F solutions does not yield a significant gain in F in the first 10 microns of the facial enamel, as determined by the etching technique under similar conditions. 3. A varnish (Duraphat) containing 5% NaF (applied three times at weekly intervals) is found to deposit considerable amounts of fluorine in outer facial enamel. Within the first 10 microns gains of more than 1000 ppm F are detected by the etching technique. Uptakes of the order about 500 ppm F are seen even at depths beyond 10 microns; penetration of F is detected down to about 100 microns' depth. Ion probe experiments show a F gain of more than 2000 ppm at a depth of about 0.3 microns. 4. In teeth extracted one day after a single application of NaF varnish, the retained fluorine is higher than in teeth retained in oral environment for one or five weeks after application. This suggests that loss of F occurs particularly during the first days after treatment. 5. The varnish, when applied every six months in permanent dentition of 15 year old children, is cariostatic on all tooth surfaces. 6. The secondary ion microanalyzer ("ion probe") is a useful instrument for the study of fluorine concentrations in dental hard tissue, and provides a special approach to the outermost regions of enamel. 7. The ion probe renders quantitative F determinations in dental hard tissue; a calibration method is available when the positive secondary ion ratios CaF+/Ca+ or F+/Ca++ are recorded versus Ca++/Ca+.

Adolescent↗
PubMedDate not supplied

Prediction of caries in pre-school children in relation to fluoride exposure.

The levels of salivary mutans streptococci and caries experience were used as predictors for caries incidence in 3 groups of pre-school children from areas with different levels of natural and topical fluoride exposure. Altogether 1022 children, 4-5 years of age at baseline, were examined according to the WHO-criteria and followed for 2 years. The low fluoride group (n = 374) had a low fluoride level in the piped water and no topical fluoride applications; the F-varnish group (n = 442) had low water fluoride but semiannual topical applications of a fluoride varnish; the optimal fluoride group (n = 206) had an optimal level of fluoride in the drinking water and semiannual F-varnish applications. The number of salivary mutans streptococci was estimated and scored at baseline with the Strip mutans chair-side method. The sampling procedure was repeated in 337 children of the low fluoride group 3 weeks after baseline. In comparison with the low fluoride group, caries incidence was 30% and 60% lower in the F-varnish and the optimal fluoride group respectively. The caries predictive ability decreased with increasing fluoride exposure. The sum of sensitivity and specificity decreased from 151% (65% + 86%) in the low fluoride group to 131% (40% + 91%) in the optimal fluoride group. The positive predictive value was highest (62%) in the low fluoride group. Repeated salivary samplings at baseline did not improve the caries predictive power. The results suggest that the overall fluoride exposure should be taken into account when caries risk assessment strategies for preschool children are developed and implemented.

Child, Preschool↗
PubMedDate not supplied

Effect of quarterly treatments with a chlorhexidine and a fluoride varnish on approximal caries in caries-susceptible teenagers: a 3-year clinical study.

The aim of this study was to compare the effect of two different dental varnishes on approximal caries incidence in teenagers with proven caries susceptibility during a 3-year period. Two hundred 13- to 14-year-old subjects exhibiting at least two approximal enamel caries lesions were selected to take part in the study. One hundred and eighty subjects participated after informed consent and were randomly assigned to two equally sized groups. One group was treated with a fluoride varnish (FV, Fluor Protector) containing 0.1% F every 3rd month and the participants of the other group were treated in the same mode with a chlorhexidine varnish (CV, Cervitec((R))) containing 1% chlorhexidine and 1% thymol. In total, each subject was treated 12 times during the experimental period. Approximal caries including enamel lesions (DMFS(appr)) were recorded from four bitewing radiographs exposed at the start and end of the study. The mean (+/-SD) caries prevalence at baseline was 2.2+/-3.4 in the FV group and 2.5+/-4.0 in the CV group. After 3 years, the average approximal caries incidence was 2.7+/-3.1 and 3.1+/-3.5 in the FV and CV groups, respectively. The differences at baseline and after 3 years were not statistically significant. In conclusion, treatments every 3rd month with either a fluoride- or a chlorhexidine/thymol-containing varnish showed a promising effect with low approximal caries incidence and progression in teenagers with proven caries susceptibility.

Adolescent↗
PubMedDate not supplied

Fluoride concentrations in saliva and dental plaque in young children after intake of fluoridated milk.

This study determined fluoride (F) concentrations in whole saliva and dental plaque after intake of fluoridated milk using a randomised crossover experimental design. Eighteen healthy children (6-8 years) were subjected to each of four different 3-day drinking regimens: (a) 200 ml F-free tap water; (b) 200 ml tap water with 1.0 mg F; (c) 200 ml standard milk, and (d) 200 ml standard milk with 1.0 mg F. A washout period of 7 days was organised between the different drinking regimens. All children used F-free toothpaste prior to and during the trial and were instructed to avoid F-rich food and drinks. F concentration in unstimulated whole saliva was determined at baseline and after 15 and 120 min and in plaque samples at baseline and after 2 h. The mean baseline values ranged from 0.01 to 0.02 mg F/l in saliva and between 10.4 and 14.2 mg F/l in dental plaque. A statistically significant (p < 0.05) increase of F was disclosed in saliva 15 min after drinking F-containing milk and water (0.052 and 0.058 mg F/l, respectively). After 2 h, the salivary F(-) concentrations were back to baseline values. In the plaque, however, a statistically significant (p < 0.01) twofold increase was found at 2 h after the intake of fluoridated milk and water, respectively. The results indicate that consumption of fluoridated milk contributes to a F storing process with significantly elevated F concentrations in dental plaque up to 2 h after intake. Further studies are required to determine the 'therapeutic concentration' of F in dental plaque after intake of fluoridated milk.

Animals↗
PubMedDate not supplied

Ion probe study of fluorine gradients in outermost layers of human enamel.

F concentrations in the outermost layers of human tooth enamel were studied with the aid of a secondary ion microanalyzer. Concentration profiles were recorded in continuous sputtering analysis from the surface down to a depth of about 0.3 micrometer. Samples previously subjected to topical fluoride treatment were compared with reference specimens. In some samples, the results were compared with those obtained at greater depths by macroscopic etching analysis.

Acid Etching, Dental↗