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Biomedical subjects

L Seppä

Publications and source records attributed to L Seppä.

At least 55 records · Page 3Linked to original sources
PubMed1989

Prevention of rat fissure caries by sodium fluoride varnish (Duraphat) with different fluoride concentrations.

125 Osborne-Mendel rats were weaned at 22-23 days, inoculated with Streptococcus sobrinus and fed a cariogenic diet for 40 days. The control group received no treatment; the study groups received applications of Duraphat containing 2.3, 1.1, or 0.6% fluoride or a placebo varnish on days 21-23. The placebo varnish had no effect on caries. Fissure caries was significantly reduced by the 2.3 and 1.1% fluoride varnishes, whereas the caries reduction found after treatment with the 0.6% fluoride varnish was not statistically significant. These results suggest that reducing the fluoride content of Duraphat by half does not significantly reduce its caries-preventive effect, but the progress of caries seems to be somewhat slower with the 2.3% fluoride varnish.

Animals↗
PubMed1989

Au, Cu, Sn, Zn and Ag ion release from some Cd-free gold solders.

The aim of this study was to determine the release of Au, Cu, Sn, Zn, and Ag from five commercially available Cd-free gold solders. The electropotential system in modified Fusayma solution was used. The cycle process was repeated between +/- 250 mV for 24 hours. To study the ion release, samples of solution were analysed during the process. Rapid release of Zn from most alloys was found. Cu and Ag ions were also released, but only small amounts of the latter. Au showed very good passivation up to 24 hours. The use of soldered joints should be reduced in order to minimize corrosion.

Copper↗
PubMed1989

Topical fluorides.

Fluoride is currently conceived as acting for the most part topically, reducing dissolution and enhancing remineralization of the enamel. The introduction of small amounts of fluoride into the mouth as often as possible is therefore important. Regular use of fluoride toothpastes is the most practicable way of maintaining elevated fluoride concentrations at the plaque-enamel interface. The importance of fluoride toothpastes as the basic caries preventive method requires emphasizing. For those who need additional fluoride therapy, frequent rinsing with dilute fluoride solutions or topical applications of concentrated fluoride solutions, gels or varnishes are the commonest alternatives. None of these methods is superior to any other. Thus, choice of method depends on costs, convenience, patient acceptance and safety.

Bacteria↗
PubMed1988

Frequency of initial caries lesions as predictor of future caries increment in children.

The aim of this study was to evaluate the predictive power of the frequency of initial caries lesions in selecting persons at high risk for caries. The subjects (n = 124) were 11-13 yr old at the beginning of the follow-up. Caries was registered initially and and after 5 yr. Evaluation of the predictions was based on cross-tabulations of the subjects according to their predicted caries risk and the actual 5-yr caries increment. Logistic regression analyses were used to produce the individual risk scores. In addition to the caries scores, age of the subjects was included in the prediction function. In bivariate analyses the total initial caries score at baseline correlated better with caries increment than FS and DS scores did (r = 0.40, 0.13, and 0.31, respectively). When past caries experience was used as predictor, 69% of the children were classified correctly into the low and high risk groups. Surprisingly, only two more subjects (2%) were classified correctly when initial caries score was included in the function. These results suggest that inclusion of initial caries score adds little to the predictive power of the conventional DS and FS scores.

Adolescent↗
PubMed1988

Effects of a sodium fluoride solution and a varnish with different fluoride concentrations on enamel remineralization in vitro.

To study the efficacy of sodium fluoride varnishes and a NaF solution in remineralization of enamel, 120 slabs of non-carious human enamel enamel were presoftened for 6 h and randomly divided into six groups. The slabs were stored in synthetic saliva for 9 days, except for a daily 30-min immersion in 0.1 M lactic acid-NaOH buffer. During the 9-day period, one group of the slabs received no treatment, and the rest were treated once or three times with 2.3% or 1.1% sodium fluoride varnish Duraphat, or nine times with a 0.1% NaF solution. Finally, the slabs were demineralized for 1 h, and the amount of dissolved Ca and F was determined. Microhardness of enamel was determined initially, after presoftening, after the 9-day period, and after the 1-h demineralization. All fluoride treatments prevented enamel softening almost completely during the 9 days, but the control slabs softened markedly. Fluoride varnishes were more effective than NaF solution. Three applications of 2.3% Duraphat were slightly more effective than any of the other varnish treatments, but one treatment with 2.3% varnish was not more effective than treatments with 1.1% varnish. Enamel treated three times with 1.1% varnish showed the greatest acid resistance during the 1-h demineralization. The results suggest that the efficacy of the varnish was not proportional to the fluoride concentration but rather to the number of applications. Fluoride uptake by enamel was greatest with the most concentrated varnish. Enamel solubility was not, however, directly proportional to the fluoride content of enamel.

Dental Caries↗
PubMed1988

Streptococcus mutans counts obtained by a dip-slide method in relation to caries frequency, sucrose intake and flow rate of saliva.

The level of Streptococcus mutans in saliva was determined by a dip-slide method in 841 13-year-old children in order to identify children with high caries risk. For each child, the flow rate of saliva was determined. Caries scores were obtained from Public Dental Health records. A sucrose intake score was calculated based on self-reported frequency of intake of six types of sugary products. As S. mutans counts increased, there was a significant trend of increased DMFS and DS scores. No linear correlation was observed between reported intake of sucrose and S. mutans counts, but the children with the highest counts (class 3) tended to have significantly higher sucrose intake than the rest of the children. The flow rate of saliva decreased significantly as S. mutans increased.

Adolescent↗
PubMed1988

Prevention of fissure caries in rats by dietary F supplement with and without topical application of F and Sr + F.

In our previous studies, combined dietary and topical fluoride have shown to be more effective than each alone. Moreover, supplementation of chlorhexidine-fluoride solution with Sr was beneficial for caries prevention in rats. In the present study, the caries-preventive effect of fluoride added to the diet plus F and/or Sr applications was studied in two experiments with rats. One group received dietary fluoride supplement only. In other groups, either a Sr solution, a fluoride varnish, or a Sr solution plus fluoride varnish were applied to newly erupted molars. In addition, one group received both topical applications of Sr + F and dietary fluoride. Caries development was followed longitudinally during periods of 15, 30 or 54 days. The greatest and most significant reduction of caries resulted from the combination of fluoride varnish plus dietary fluoride supplement. Treatment with Sr solution at the beginning of the experiment had no effect on caries either alone or combined with fluoride varnish. It was found that caries increased rapidly and then levelled off after the 30-days feeding period in all groups. In the treatment groups, however, caries was arrested at a considerably lower level than in the control group.

Administration, Topical↗
PubMed1985

A scanning electron microscopic study of bacterial penetration of human enamel in incipient caries.

In 23 human teeth, cracked enamel under white spot lesions without any visible loss of tooth substance was examined. Bacterial contamination from the enamel surface was prevented by brushing and consequent fixing of the remaining surface coatings before the enamel was fractured. In 7 of 23 specimens, bacterial colonies were observed under the enamel surface, sometimes as deep as the enamel-dentine junction and the dentine. In most samples the subsurface enamel appeared to be partly disintegrated. Bacteria can thus be found under surface enamel at an early stage of caries while the surface is still intact.

Adult↗
PubMed1984

A scanning electron microscopic study of early subsurface bacterial penetration of human molar-fissure enamel.

Cross-sections of occlusal fissures in clinically-sound, partly-erupted human third molars were examined using scanning electron microscopy. In several specimens, microbes had invaded enamel under an apparently intact enamel surface and formed colonies within the prism structure. Bacteria were located also between enamel prisms. In some samples, colonies were observed in dentine. Most of the organisms were rod-shaped or filamentous. The results indicate that plaque bacteria can invade enamel before initiation of caries is clinically observable.

Adult↗
PubMed1984

Exchange of fluoride between bovine enamel and the surface-related cells of the oral bacterium Streptococcus mutans.

Standard areas of intact bovine enamel surface were fluoridated with dental F-varnish for 24 h and then cleaned from varnish residues and thoroughly rinsed with distilled water. Sucrose fermentation by a plaque-like layer of Streptococcus mutans cells covering such an enamel surface was accompanied by a rapid but transient accumulation of F of enamel origin by the Strep. mutans cells and by a pH drop in the plaque to pH 4.0. The uptake of F from the surface by the control cells, utilizing their carbohydrate stores and causing a smaller pH-drop, was slow but no release of F back to the cell exterior took place within 18 h. In a second experiment, F- varnished and placebo- varnished bovine enamel granules were used as above, but they were not thoroughly washed after being varnish-treated and cleaned. Both the sucrose-fermenting and the control layer of Strep. mutans rapidly released appreciable but equal amounts of fluoride from the F-treated enamel. The accumulation of F of enamel origin by the Strep. mutans cells with or without sucrose was rapid and of almost the same magnitude. In the model with the sucrose-utilizing Strep. mutans and the F-treated enamel granules, the plaque pH-drop was less and the dissolution of the enamel Ca and P completely prevented compared to the respective changes in the sucrose-utilizing model with placebo-treated enamel granules.

Animals↗
PubMed1984

Caries prevention in rats by fluoride varnish treatment combined with addition of fluoride to dietary sugar.

Osborne-Mendel rats were fed a cariogenic diet containing 43% sucrose for 48 days. The control group received no additional treatment. The teeth of the second group received topical treatment with a sodium fluoride varnish which was applied twice onto newly-erupted molars. The third group received topical treatment with the sodium fluoride varnish combined with a NaF + Mg addition to the diet. In both treatment groups, caries was significantly reduced as compared with caries in the control group. Combined treatment was significantly more effective than was the varnish alone. In spite of the high fluoride concentration in the varnish, no changes in the oral mucosa were found at the end of the study.

Animals↗
PubMed1984

Effect of chlorhexidine-fluoride applications without and with Sr and Zn on caries, plaque, and gingiva in rats.

Molar teeth of four groups of Osborne-Mendel rats, kept on a cariogenic diet, were treated once per day for 48 days with either distilled water (solution C), a solution containing 0.05% chlorhexidine gluconate and 0.04% NaF, pH 5.8 (solution CXF), CXF plus 1000 ppm Sr (solution CXFS), or CXFS plus 1000 ppm Zn (solution CXFSZ). Caries of the hemi-sectioned lower molars was scored according to grades of severity, and the extent of the buccal plaque was estimated. Inflammatory cell infiltration, vascularity, and thickness of the oral mucosa were estimated from stained sections of the buccal oral mucosa to detect possible adverse effects of the treatments. Fissure caries lesions with involvement of the dentin were reduced by 57% (p less than 0.01) with the CXF treatment and by 68% (p less than 0.001) with the CXFS treatment. The CXFSZ treatment reduced the fissure caries least (44%, p less than 0.05), but it appreciably reduced the extent of plaque. The mucosal changes were greatest in the group receiving the CXFSZ treatment, but they were generally small and at a non-pathological level. Supplementation of the CXF solution with Sr thus appeared beneficial for caries reduction.

Animals↗
PubMed1984

Post-treatment effect of fluoride varnishes in children with a high prevalence of dental caries in a community with fluoridated water.

Children with a high prevalence of dental caries living in a community with fluoridated water had received semi-annual half-mouth applications of one of two fluoride varnishes for three years. Two years after the applications were discontinued, we studied the post-treatment effect of the varnishes. The absolute reduction in caries found during the treatment was retained, but the cariostatic effect did not continue after treatment. This finding suggests that fluoride varnish applications should not be discontinued after three years.

Adolescent↗