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Biomedical subjects

H Luoma

Publications and source records attributed to H Luoma.

At least 37 records · Page 2Linked to original sources
PubMed1988

Erosive effect of a sport drink mixture with and without addition of fluoride and magnesium on the molar teeth of rats.

A sport drink mixture (pH 3.2), either as such or supplemented with 15 ppm F or 38.5 ppm Mg or both, was given to Osborne-Mendel rats as the only liquid for 42 days. The erosion was scored on the lingual surfaces of the first mandibular molar teeth. Sport drink caused marked erosion, but in the groups where fluoride, alone or with magnesium, was added to the drink, the erosion damages were less severe. Magnesium alone had no clear effect on erosion. Dental plaque, induced by a powdered diet containing 15% sucrose, seemed to modify the erosion process by covering a part of the enamel and thus protecting these areas from the direct effect of acidic drink.

Animals↗
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↗
PubMed1988

The role of magnesium in the aetiology and prevention of caries: some new findings and implications.

While some epidemiological studies seem to indicate that a high intake of magnesium should be associated with a low prevalence of dental caries, the results of experimental studies are mainly equivocal. Magnesium is probably not bound to the apatite lattice of dental enamel or dentine, or it is bound to a small degree only. It is mainly located in the hydration layer of the apatite crystallites. In the dental caries process it is preferentially dissolved together with the carbonate of the mineral phase. It is not known to what extent feasible dietary changes can modify tooth magnesium content during pre-eruptive tooth development. Animal experiments indicate that the elevation of dietary magnesium alone after tooth eruption has no definite capacity to modify the occurrence of dental caries. When fed in combination with small fluoride supplements in the diet magnesium and fluoride may support each other in preventing various calcium salt imbalances such as dental caries, arteriosclerosis and nephrocalcinosis. Although some recent in vitro findings indicate that extra magnesium in the fluid environment of cariogenic streptococci may protect them against the inhibitory action of fluoride, such magnesium changes do not seem possible in the human mouth under present or envisaged dietary conditions.

Bacteria↗
PubMed1987

Excretion, serum, bone and kidney levels of F in rats after a high single dose of F and Mg + F.

The aim of this study was to clarify the mechanisms by which Mg protects the organism against the acute toxic effects of F. A single dose of F (30 mg F/kg as NaF) was given to young rats by gastric gavage with or without a prior dose of Mg (as MgCl2) equivalent to the F dose given (groups MgF and F, respectively). Feces and urine, serum, femoral bone and kidney were sampled 24 h after the doses were administered. Mg given 30 min before fluoride did not modify elevation of the F content in serum or in femoral bone when each was measured 24 h after the F dose. Except for fecal excretion of F, Mg did not significantly influence F excretion. However, the mean renal content of calcium, which was highly elevated by F alone, was markedly less in the MgF group. The renal content of Mg was at almost the same level in the MgF group as in the controls. The antidotal effect of Mg against F toxicity cannot primarily be due to interference with the absorption of F. Prevention of the nephrocalcinotic effect of F by Mg appears to be a mechanism for reducing the acute toxic effects of F, but our results suggest that other tissue and intracellular mechanisms may be more decisive.

Animals↗
PubMed1986

Effects of calcium, fluoride and magnesium supplementations on tissue mineralization in calcium- and magnesium-deficient rats.

There is considerable uncertainty about the interrelated effects of calcium (Ca), magnesium (Mg) and fluoride (F) on hypocalcification of the skeleton and Ca accumulation in vital soft tissues. This paper describes experiments with rats fed a diet deficient in Ca and Mg, the latter deficiency being accentuated by a low potassium content. For different groups the drinking water was supplemented with Ca, Mg, F, Ca + F or Mg + F; Ca and F were supplied as chemically compatible compounds. At the end of the 54-d experiment, plasma Ca was strongly reduced in the Ca-deficient groups. Plasma Mg was reduced particularly in the test groups supplied with Ca, without any influence of F supply or varying plasma F. Ca accumulation was much more pronounced in the kidneys than in the heart or aorta, but was mitigated by both Mg and F supplementation. Bone mineralization disturbance due to the dietary imbalance was preventable only by Ca or Ca + F supplementation, and was less in alveolar bone than in femur. However, the Ca supplement was associated with the highest aorta and heart Ca contents, and Ca + F was associated with marked renal Ca accumulation; adequate Mg supply may be essential with Ca + F administration against osteoporosis.

Animals↗
PubMed1986

Effect of a sport drink mixture with and without addition of fluoride and magnesium on plaque formation, dental caries and general health of rats.

A sport drink mixture (pH 3.2) containing 6% sucrose was given to Osborne-Mendel rats for 42 days. In some experimental groups the drink was supplemented with 15 ppm F, 38.5 ppm Mg or both F and Mg. The rats were fed a slightly cariogenic powdered diet containing 15% sucrose. Sport drink mixture increased significantly the accumulation of plaque but, compared with a group that drank distilled water, did not affect caries. Addition of fluoride to the sport drink mixture, alone or with magnesium, significantly reduced caries and tended to decrease plaque; addition of magnesium had no clear effect on plaque or caries. In spite of the fact that the rats had a sport drink mixture as the only drink for 6 wk, there were no untoward effects on growth, in histological studies of the inner organs, or in Ca, Mg, Na and K contents of kidney, heart and aorta.

Animals↗
PubMed1985

Salivary Streptococcus mutans count and gingivitis in children after rinsing with a chlorhexidine-fluoride solution with and without strontium.

Thirty schoolchildren, 9-12 yr old with high DMF score, rinsed their mouths twice a day for 3 days with a chlorhexidine-fluoride (CXF) solution or a chlorhexidine-fluoride-strontium (CXFSr) solution. Streptococcus mutans counts (CFU) were made from saliva incubated on MSB agar and the gingival bleeding was recorded both before and after the rinsing period. S. mutans count decreased significantly immediately after the rinsing with each of the solutions (from 650 X 10(3) to 170 X 10(3) CFU/ml by CXF and from 500 to 170 X 10(3) CFU/ml by CXFSr). Within about 18 days after the rinsing with each solution the salivary S. mutans counts returned to the original level. Gingival Bleeding Index (GBI) was significantly reduced by half through the CXF rinsing while the slight reduction by CXFSr was nonsignificant. Both of these changes were temporary. The results suggest that short rinsing periods with the CXF solution may be more advisable than daily rinses as a contribution to the maintenance of oral health in subjects or groups in need of such a prophylaxis. The weaker effect found with the CXFSr solution suggests that the cariostatic effect recently found in rats with the same solution may be due to other mechanisms than reduction of the oral S. mutans count.

Child↗
PubMed1985

Fluoride in sugar.

Results of caries model studies in vitro and in animals suggest that the tooth-protective potential of fluoride may be best utilized if fluoride is brought to the local caries milieu at the moment of each caries attack. Two clinical trials performed so far indicate that a reduction in caries increment of about 40 per cent can be obtained within 3 years through small (0.5-1.0 mg) daily intakes of fluoride when it is incorporated in highly cariogenic sucrose products or in tablets having a sucrose base. When incorporated in sucrose products, fluoride caused a complete arrest of caries during the third year. There was substantial accumulation of the supplemental fluoride in surface and subsurface enamel beneath the plaque fermenting the F-supplemented sucrose. This may be one of the preventive mechanisms involved. In plaque fluid, the supplemental fluoride, together with fluoride released from the plaque material and by the action of acid on the surface enamel of high fluoride content, may strongly reduce further enamel dissolution and promote its remineralization. Further metabolism of the plaque bacteria including their acid production may also be inhibited. Among the many advantages of using this principle are that: the supplemental fluoride in sugar automatically seeks the caries risk subjects who use sugary products; the amount of fluoride needed per kg of sugar may remain low and thus the risk of excessive intake of fluoride may also be low; the technical process is low in cost and easily performed; and the products are easily distributed nationwide. Furthermore, non-fluoridated sugary products may still be distributed to those who may continue to prefer them.

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

Microbial invasion and subsurface colonization of rat enamel in early fissure caries observed by scanning electron microscopy.

In order to find out whether microbes can be detected in the incipient rat caries lesions underneath the visibly intact enamel surface, the maxilla of OM-rats, fed a cariogenic diet, were fixed and partially bisected sagittally with a thin saw. The individual teeth were finally split with a knife to get a crack surface from the fissure region. Selected tooth halves showing slight carious changes at the dentin-enamel junction were prepared for SEM and examined. In many preparations, colonies of organisms were found firmly attached to the crack surface. Single, predominantly coccus-like organisms and a few rods could be seen mostly located in the interprismatic furrows at varying depth throughout the enamel. Some lacuna-like hollows, with or without the occupant organisms, could be seen carved in the prism structure. The enamel side of the DEJ in the lesion area could be completely covered by the microbes. In samples representing arrested caries, amorphous precipitates were found at the interprismatic substance of the DEJ region.

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↗