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The potential use of different vehicles for delivering fluoride to prevent dental caries has been discussed recently in Mauritius. Water fluoridation was found not to be feasible, and extending the fluoride tablet program would not be easy. Thus, sugar fluoridation as one possibility was considered. For these purposes, the average fluoride and sugar intake was estimated in Mauritius. The results are based on two studies-a Survey on Diet, Health and Lifestyle of Youth in Mauritius (1990) and the Mauritius Diet and Health Survey. Information was collected by trained interviewers using food-frequency and 24-hour-recall questionnaires. The daily total sugar intake, manufactured and natural, was found to be 62 g per day in young people and 50 g per day in adults. In the younger groups, daily frequencies of raw sugar, sweets, and biscuit (cookie) consumption were 1.5, 0.2, and 0.2 times a day, respectively. For adults, the mean daily frequency of consuming sugar-containing foods was 2.6 (SD = 1.3). The daily sucrose intake was rather high, representing about 10% of the daily energy intake. The fluoride levels of foods were calculated by use of Finnish and other available fluoride tables. The mean fluoride intakes per day were 0.64, 0.72, and 0.62 mg per day for 8-17-year-, 18-24-year-, and 30-64-year-old groups, respectively. The median fluoride intake for the oldest group was 0.62 mg/day. The estimated fluoride intake from food did not correspond with the proposed level for the prevention of caries (Murray, 1986) except for the 18-24-year-olds, where it might have been just above the lower recommended limit. However, further data based on analysis of the fluoride contents of Mauritian food samples, especially of whole daily diet, are needed.

In order to study the effects of different glass ionomers on the metabolism of Streptococcus mutans, test slabs of freshly mixed conventional glass ionomer (Fuji), silver glass ionomer (Ketac-Silver), composite (Silux), and 2-week-old Fuji were fitted into the bottom of a test tube. A plaque-like layer of S. mutans strain Ingbritt was centrifuged onto the test slabs, and the samples were incubated for 20 h in 1.7% (w/v) sucrose solution. For freshly mixed Fuji and Ketac-Silver, the pH fall was significantly smaller than for old Fuji and composite. These materials also released the largest amount of fluoride into the fluid phase. Incubation with glass ionomer materials led to an increase in the cellular concentration of fluoride in bacteria, but intracellular fluoride did not correlate with the fall in pH. The lowest pH was associated with the lowest cellular magnesium content. Ketac-Silver released large amounts of calcium in the fluid phase, and the cellular calcium content was doubled in this group. The results show that freshly mixed glass ionomers affect acid production and electrolyte metabolism of S. mutans in vitro. The effect of conventional glass ionomer, however, seems to disappear after a few weeks. The effects of calcium and silver released by cermet glass ionomer deserve further study.

Monitoring of the tissue graft during and after the grafting operation is useful in reducing the risk for tissue ischemia, which may lead to even graft loss. Possible complications should be detected as early as possible in order to minimize the re-operation. Three models representing muscle tissue were created in FEMLAB: an isotropic model and two anisotropic models, the latter ones having the electrodes either perpendicular or parallel to the muscle fibres. Eleven tetrapolar measurement configurations having varying inter-electrode distances were modelled in each model to study their measurement sensitivity distributions. The results showed effects of anisotropy on both the measured impedance and the associated sensitivity distributions. For example, regions of negative sensitivity or depth for maximum sensitivity were dependant on whether the electrodes were placed perpendicular or parallel to the muscle fibres. The results point out also how to estimate the tissue anisotropy and how to measure impedance changes deeper in the tissue volume. The impedance method seems to be suitable for monitoring the muscle graft healing. However, more work is needed for reliable interpretations between the measured impedance and physiological changes.

Recent findings indicated that a low fluoride supplement, especially with a low magnesium supplement in the basically low magnesium diet of genetically hypercholesterolaemic male RICO rats, may prevent the generation of atherosclerotic serum lipid profile. In the present study, several plasma lipids/lipoproteins were measured in the same strain of rats after a later growth phase. The control group C was fed an adequate diet with 45 per cent sucrose plus some cholesterol while the dietary fluoride was very low (1.1 mg F/kg of diet). In diet of group D, the Mg content was reduced to about one seventh of Mg of group C, i.e. to 122 mg/kg. Diet of group E was as that of group D with F content elevated to 17.2 mg/kg. Diet of group G was as that of group E with Mg content elevated to 220 mg/kg. The feeding period was terminated at 12 h deprivation of food and following exsanquination. Total plasma cholesterol in group C was 4.5 mmol/L. The central factor in causing reduction in growth rate and several plasma lipids and their lipoprotein subfractions appeared to be the magnesium deficiency. However, the greatest significant reductions in plasma cholesterol, plasma free cholesterol, plasma and VLDL esterified cholesterol and also HDL cholesterol, HDL esterified cholesterol and plasma triglycerides from those levels of the control group C were found in group G (fluoride and magnesium supplements). Supplementation of fluoride alone in group E reduced only plasma and VLDL esterified cholesterol. In the present male RICO rats, low dietary F and Mg supplements, separately, and especially together, may participate in the regulation of the outcome of atherosclerosis via affecting several plasma lipid risk factors known to associate with the development of atherosclerosis.

To combat dental caries, a chemical has been sought that possesses stronger antimicrobial properties than fluoride in support of its physicochemical tooth-protecting properties. These searches have led to several agents, of which chlorhexidine (CH) appears most effective. To reduce local side effects of the well-known 0.2% CH mouthwash, a 0.05% CH gluconate + 0.04% NaF solution, pH 5.9, has been developed. Use of this combination over a 2-year period resulted in a 53% reduction in caries increment and a 75% reduction in gingival bleeding, i.e. a clear duality of prevention of oral disease (Luoma et al. 1978). Staining of teeth was minimal and easily removable in about one third of the subjects. To lessen the contribution of patients, chlorhexidine gels, without but more especially with fluoride have been professionally administered. Reductions in salivary mutans streptococci after short periods of gel applications have been found to persist longer than reductions after brief periods of mouthwashing. Reductions of approximal caries increment by about 50% in children, and root surface caries in adults have been obtained through use of CH gels. The effect on root surface caries in adults was equal to that obtained through use of local fluoride applications. Dental CH varnish seems promising, especially because a very short contact time with a tooth may be sufficient to reduce mutans streptococci. No simultaneous effects against caries and gingivitis of CH gels or varnishes has been reported. Comparisons of CH solutions, gels and varnishes, with or without fluoride, in relation to their potentials for preventing oral disease in subjects at risk remain to be accomplished.

In order to study the amount of fluoride originating from glass ionomer, a test appliance was constructed and set on upper molars of sixteen volunteers using glass ionomer. The control appliance was set on the contralateral tooth using composite. Six weeks after the setting of appliances, plaque samples were taken and analysed. Mean amounts of protein corresponding to the amounts of plaque were equal in the test and the control groups. The mean fluoride/protein ratio in plaque was 80 times higher in the glass ionomer group than in the composite group. With this sampling method it is possible to collect sufficient amounts of plaque for quantification of plaque fluoride.

The main clinical and theoretical studies on caries etiology and prevention and on general health published by the author and his coworkers since the beginning of the 1960s are briefly reviewed. Among the caries prevention methods published by previous authors, the Finnish trials on fissure sealing and fluoride varnishing showed distinct preventive effects. On the basis of these and later supporting findings, these methods were rapidly and widely adopted in the dental health care of Finnish children and adolescents. A chlorhexidine-fluoride mouthrinsing solution, developed by the author, exhibited simultaneous reduction of both caries and gingivitis among high -risk children and this preparation or chlorhexidine-fluoride gels have been widely prescribed for risk subjects, especially those with a caries risk. Despite the good caries prevention results obtained through fluoridation of sugar products and in respective model studies, this procedure has not been passed for commercial use in Finland. The translocation of phosphorus, potassium and fluoride between microbes of dental plaque origin and their environment, including the respective elements of enamel origin, were presented as a partial explanation for the role of phosphates and fluoride in caries etiology and/or prevention. Animal experiments elucidated the killing mechanism of a high single fluoride intake and its prevention by magnesium with explanatory changes in cardiac calcium. On the other hand, experiments on prolonged intakes of low dietary fluoride by rats confirmed earlier findings on the potential of fluoride in preventing calcium salt imbalances in internal organs. This was accomplished with a fluoride intake sufficient for caries reduction. The ability of two strains of the mutans streptococci and a Lactobacillus to invade enamel and dentine and to destory these structures from the inside before the cavitation phase of caries was demonstrated with gnotobiotic rats. The marked caries reduction among Finnish children and adolescents within the past 20 years appears to be due to a number of factors.

The LD50 for fluoride was elevated from less than 60 mg F/kg body weight to 172 mg F/kg when magnesium (as MgCl2), equivalent to 3 times that of F, was administered by gavage 30 min after the F dose. A dose of 30 mg F/kg elevated the mean steady state of F in serum nearly 1.5-fold and in femoral bone nearly 2-fold when administered with or without the subsequent Mg dose and observed 24 h after the electrolyte dosages. Also, in 24-hour urine the mean F excretion was highest in the F and FMg groups. The total F excretion (fecal + urinary) was elevated 8- and 10-fold when fluoride was administered with or without magnesium, as compared to control levels. Magnesium administration with fluoride did not significantly modify the above mean values of the group given fluoride alone. This suggests that interference with the absorption of fluoride was not the primary protective function of magnesium against the acute toxicity of fluoride. Additional experiments, conducted to further clarify the toxic mechanism of fluoride and the protective mechanism of magnesium, resulted in the following findings: An intraperitoneal dose of 20 mg F/kg elevated fluoride concentration in serum in 1 h about 20 times compared to the controls. Magnesium injected simultaneously with fluoride did not modify the effect of fluoride alone. No significant changes were found in the concentrations of K, Mg, Na or Ca of the lung, skeletal muscle, kidney or liver after these injections except for some trend of elevation of Ca in the heart. However, after a dose of 30 mg F/kg i.p., the heart Ca/Mg mole ratio was elevated within 1 h from 0.037 to 0.194, while all of these rats died within 1 h after the injections. When magnesium, equivalent to 3 times the amount of fluoride was injected, this mole ratio was only 0.095, and all rats in this group survived over 1 h. These results suggest that the lethality of fluoride may be dominantly mediated by the elevated Ca (Ca/Mg ratio) in the heart muscle and that this is correctable by Mg.

A total of 164 schoolchildren, aged 11–15 years with high DMF scores was divided into 4 groups. Subjects of the CXF group brushed their teeth after school lunch and rinsed their mouths with a solution containing 0.05% chlorhexidine gluconate + 0.044% NaF in succinic acid/NaOH buffer, pH 5.9. The F group had 0.044% NaF in the buffer. The PI group used a placebo solution and the C group served as the basic control. Respective nonabrasive toothpaste preparations were used in the evenings and twice a day during weekends and the holidays. After 2 years, the mean DMFS increments in the C, Pl, F and CXF groups were 6.3, 5.1, 4.3 and 2.9, respectively. The percentage of subjects with bleeding vestibular gingival units examined in different groups had changed from initial to final value as follows: C, 40–63; PI, 50–49; F, 71–47 and CXF, 63–14.

The study was conducted to observe in rats the possible modification of ectopic calcification by magnesium-orthophosphate-fluoride combinations, used as additives of diet for reduction of the cariogenicity of the sucrose. In rats, fed low magnesium diets, extra dietary orthophosphate (2%) considerably elevated the calcification of kidneys. Further additions of magnesium and fluoride partially reduced this adverse effect of phosphate. While the calcium content of the aorta in rats, fed low magnesium-high phosphate diet, was considerably elevated, the further addition of magnesium (40 ppm) partially reduced the calcifying effect of phosphate in aorta. Fluoride (15 ppm) together with magnesium (40 ppm) completely reduced it. The appearance of renal calculi caused by a low magnesium diet or by extra phosphate were similar according to light and electron microscopy except for the larger size in the latter case and occasional extratubular calculi found in groups with high phosphate-low magnesium and high phosphate with added magnesium diets.

Washed cells of the FA-1 and K-1 strains of Streptococcus mutans were incubated in buffered solutions, pH 5.9, that were initially either saturated or slightly undersaturated by add

A layer of cells from buffered Strep. mutans suspension (pH 5.8), with or without sucrose, was centrifuged on bovine enamel surfaces. Fluoride was added to a part of the samples (final F 25 parts 10 6 ). Control and test samples were incubated at 37°C for 18 h. The pH of the fermenting plaque dropped to 4.15. When F was present, the final pH was 4.45. Microhardness of the enamel surface was reduced by the presence of sucrose but less in the presence of F. Enamel Ca was liberated during fermentation, but only into the fluid and less in the presence of F. The weight ratio of Ca and P released by sugar fermentation was 3.14 and 1.91 when F was present. The F content of enamel surface was only slightly increased ( 130 parts 10 6 ) by the F in distilled water alone. Subsurface enamel gained more F ( 280 parts 10 6 ). When artificial plaque was present, addition of F increased the F content of enamel surface by 450 parts 10 6 and F of subsurface by 210 parts 10 6 . The addition of F increased the enamel F content to the greatest extent under the fermenting plaque, 680 parts 10 6 in surface and 400 parts 10 6 in subsurface enamel, compared to the values of the enamel under non-fermenting plaque.

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.

Four per cent of the sucrose component of a cariogenic diet of the 580 type was replaced by a combination of Na2HPO4 + NaH2PO4 + KH2PO4

The average pH change from the control value 6.72 for 19 subjects was -0.59 during ingestion of experimental sucrose tablets and -0.84 after ingestion. There was a significant positive correlation between the magnitude of the pH decreases and the amount of plaque. There was no correlation between the magnitude of the pH changes and the DMFS index.

Non-growing cells of the K-1 strain of Streptococcus mutans, subjected to the influences of certain alcohols, chlorhexidine, fluoride or combinations of these factors, released varying amounts of both potassium and phosphate on incubation at pH 5.8. The combinations caused greater leakages of both potassium and phosphate than did each factor when used singly. Propanol enhanced the influence of both chlorhexidine and fluoride on the cellular potassium and phosphate content or accumulation. After pretreatment with one or more of these substances, the cells were less able to produce acid during fermentation of sucrose, especially when propanol was used in the pretreatment. The reduction of enamel solubility that was obtained through a pretreatment with sodium fluoride was not altered by propanol and chlorhexidine when used in the pretreatment together with the fluoride.

— The purpose of this study was to test the retention as well as the caries reduction potential of a fissure sealant under Finnish dietary conditions. The 150 children who served as subjects were selected on the basis of having at least one pair of sound permanent molars. Two hundred first molars, 43 premolars and 119 primary molars were sealed, while the respective tooth from the other side of the jaw was left untreated and used as the control. The findings after 6 months revealed that all 362 sealants persisted. Among the sealants of the first permanent molars, 99% were in excellent condition. All sealants of the permanent premolars and of the primary molars were excellent. Among the permanent control molars 43 (22%) showed carious fissures while among the sealed permanent molars, only 3 (1.5%) had carious fissures. This gives a 93% reduction of the fissure caries. Both the control and the sealed premolars were all sound. None of the sealed primary molars were decayed compared to 7.6% decayed on the control side.

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.

Mentally handicapped children, aged 5--15 years and living in institutions, received fluoride supplement in several sugar products of their diet; in candies, marmalades, jams, fruit juices and in sweet desserts corresponding to 10 mg F as NaF per kg of the sugar (sucrose or glucose) of each product. To two of the four daily candies was also added a NaHCO3 + KH2PO4 mixture (mole ratio 9.8/l, resp.) to substitute for 2.5% of the sugar of the candy. The control children received the respective products without the additives. After stepwise exclusions of subjects for various reasons, e.g. for the absence of permanent teeth, low initial caries activity, strong medication, Down's syndrome, etc., the mean DMFS-increment in the remaining 43 control subjects was 4.5 and in the 41 test subjects 2.6 lesions/100 surfaces at risk, i.e. 42% reduction. Caries arrestment had occurred in these test subjects after the first year, while in the respective controls it was continuously increasing. Among numerous oral and body parameters studied, only surface enamel fluoride in primary teeth was increased by the fluoride supplements and urinary phosphate and calcium excretion decreased.

To study the influence of drinking water composition on the risk of myocardial infarction, the following study was conducted: The cases (C), men 30-64 years of age, had been discharged with a first acute myocardial infarction (AMI) from Kotka Central Hospital. The hospital controls (HC), matched for age and type of community, were selected for each case among surgical patients. Population controls (PC), matched for age and municipality, were drawn for each case from the population register. Subjects submitted a sample of their drinking water and a filled-in questionnaire. After exclusions, a series of 50 C-HC and 50 C-PC pairs was finally constructed. The point estimate of relative risk (RR) for the association between low F (less than or equal to 0.1 ppm) and increased risk of AMI was 3.0 in the C-HC series. In the C-PC comparison, RR was 4.4 RR for low Mg (less than or equal to 1.2 ppm) was 2.0 in the C-HC comparison and 4.7 in the C-PC comparison. The results are consistent with the hypothesis that both a low F and a low Mg intake are conducive to atherosclerosis leading to AMI.

Magnesium chloride, administered by gavage to fasting young rats, 30 min prior to sodium fluoride, elevated the LD50 for fluoride from 76 to 104 mg/kg body wt. The LD50 was elevated to greater than 180 mg/kg when magnesium was given in a dose equivalent to 2 or 3 times that of fluoride. In two experiments, a dose of 50 mg F/kg caused a mean 14- and 19-fold increase above the level of the control animals in the renal calcium content. The nephrocalcinotic effect of fluoride was nearly completely prevented by administering magnesium in a dose which is 3-fold the equivalent of the fluoride dose 30 min prior to fluoride.

To elucidate further our previous findings on the corrective effects of dietary magnesium, phosphate and fluoride additives on the disturbed calcium phosphate balance of the body, including caries, the experimentation was continued by varying the basal diet and the concentration of the additives. Addition of orthophosphate alone to a magnesium-deficient cariogenic diet strongly reduced fissure caries. This was accompanied by an appreciably reduced rate of growth. Phosphate addition per se also promoted both renal and aortic accumulation of calcium as well as accumulation of dental calculus. These undesirable effects of phosphate could be reduced or prevented by further addition of magnesium or fluoride or preferably by both simultaneously. All three additives together reduced fissure caries significantly. During low or medium basal dietary intake of magnesium, the fluoride, when fed with phosphate, reduced caries significantly too, but this could not fully correct phosphate-induced renal calcium accumulation. The additional presence of magnesium was necessary for the full correction of the renal calcium content. Aortic calcium was increased by phosphate in magnesium-deficient rats but it was corrected by fluoride. Phosphate-induced dental calculus accumulation was reduced by fluoride and magnesium together on a high-magnesium basal diet. The results suggests a possibility of preventing the mineral disequilibrium of the body, i. e. demineralization of hard tissues and mineralization of soft tissues through some simple alterations in food composition.

Magnesium, orthophosphate and fluoride salts were added singly or in combinations to high-sucrose cariogenic diets in rats. Both the orthophosphate and fluoride, when added singly, reduced the incidence of caries. However, the greatest caries reductions (maximum 94 per cent) were obtained by combinations of all three additives. Dental calculus formation was increased by phosphate and slightly reduced by fluoride singly. The enhancement of calculus formation, caused by phosphate, tended to be reduced by further addition of the other factors, magnesium and fluoride.

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.

The caries-conducive streptococcus K-1, suspended in buffer, pH 5.8, under non-fermenting conditions, caused the release of more phosphate from the enamel than did the buffer alone. When rat tooth crowns, labelled with 32 P, were incubated with a suspension of non-fermenting streptococci in buffer, the uptake of 32 P of tooth origin by the organisms was more in the presence of potassium than in the presence of sodium. A factor capable of releasing enamel phosphorus, was eluted from the non-fermenting bacteria with strong chloride solutions. The factor was active in the presence of potassium ions. The release of enamel phosphate occurred again after precipitation of the eluted factor with acetone and buffer, pH 6.2, and the redissolution of the precipitate in water. This preparation also showed acid phosphatase activity against p -nitrophenyl phosphate with a peak activity at about pH 5.8. Both the eluted and uneluted cells showed acid phosphatase activity against the above substrate with the peak value at a more acid pH than that of the eluted preparation. The eluted cells also showed alkaline phosphatase activity against p -nitrophenyl phosphate.

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.

The caries-conducive strain FA-1 of Streptococcus mutans removed more glucose than sucrose during anaerobic incubation, mainly at pH 5.8, in a medium that did not promote growth. The addition of fluoride reduced the sugar disappearance but this reduction was partly alleviated by extra potassium. The uptake of potassium by the cells was also greater in the presence of glucose than sucrose. Potassium was extruded from both fermenting and non-fermenting cells on addition of about 50 ppm fluoride. This was accompanied by a rapid uptake of fluoride by fermenting cells followed by an immediate release back into the fluid phase. Simultaneously, the concentration of intracellular sugar was higher in the presence of glucose than of sucrose. The intracellular sugar increased during the initial disappearance of the external sugar but diminished during the period of reduced sugar utilisation. Fluoride or potassium modified the intracellular sugar changes only slightly or negligibly. Acid production from the cells was greater from glucose than sucrose and both were slightly enhanced by potassium. Acid production was completely inhibited by about 50 ppm fluoride concentration. The results suggest a close association of potassium transport of this streptococcus to sugar uptake and metabolism. The inhibition by fluoride of sugar uptake and metabolism seems to be largely due to its interferring action of the cation translocation and vice versa.