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A cross-sectional clinical study showed that the prevalence of caries among Indonesian soldiers was low, compared with that found in corresponding Western populations. Also, the progression of caries was very slow, and caries was limited almost exclusively to the occlusal surfaces of the teeth. Among officers, the prevalence of caries was lower than it was among other ranks of the same age. The low general prevalence of caries among Indonesian soldiers may be related to diet. Rice was the major source of carbohydrate for the soldiers, and their sucrose consumption was 10 kg per person per year. Their drinking water contained a low concentration of fluoride (0.1 ppm). In spite of massive accumulations of calculus, the periodontal health of young soldiers (less than 26 yr) was also good. Among those in higher age groups, however, periodontal health had deteriorated, but even in a group aged 40-46 yr, no teeth had been lost as a result of periodontal disease. Among officers, periodontal health was better than it was amongst other ranks of corresponding age. The officers had been accustomed to brushing their teeth regularly, whereas the other ranks had not. It thus appears that toothbrushing may help to preserve periodontal health, even when large amounts of calculus are present on the teeth and there is no opportunity for it to be removed regularly by a dentist.

The retention of alkali soluble (CaF2) and alkali insoluble (fluorapatite) fluoride in sound enamel and demineralized enamel 2 wk after application of Duraphat was investigated in a group of orthodontic patients from whom pairs of homolog premolars were to be extracted. Demineralization of the enamel was induced during a 4-wk period prior to application of fluoride by applying orthodontic bands to the premolars. The bands also remained attached to the teeth during and after application of fluoride (2 wk) to maintain a cariogenic environment. Three consecutive enamel layers (approximately 5 microns) were subsequently etched off. A significant uptake of fluoride in the first and second layer of sound enamel and in all the three enamel layers of demineralized enamel was found. More fluoride was found in demineralized enamel and a higher proportion of this fluoride was found to be in an alkali insoluble form compared with the fluoride in sound enamel. The SEM study showed a rough enamel surface after three consecutive acid etchings. The etching pattern differed within the etched area. It was suggested that the variation in etching pattern might be due to differences in orientation of the crystallites and the original surface morphology.

This study aimed to assess the in vitro antimicrobial effect and in vivo plaque-inhibiting capacity of chlorhexidine (CH) combined with the nonionic detergent Triton X-100. Synergistic inhibition was observed by the combination of Triton X-100 and CH on in vitro growth of S. sobrinus OMZ 176 and of S. sanguis 10556. In the clinical experiments, 10 subjects rinsed twice daily with 10 ml aqueous solutions of 11.6 mM Triton X-100, and 0.55 mM CH, and with a combination of the two agents. All mechanical oral hygiene was suspended during the test periods. Sucrose enhanced plaque accumulations were recorded after 4 days of rinsing. The combination of CH-Triton X-100 decreased plaque accumulations significantly compared to placebo, but was less effective than CH alone (P less than 0.05). Thus no beneficial clinical effect was gained by combining the nonionic agent Triton X-100 with the cationic agent CH. The results also clearly demonstrate that addition which increase the antibacterial activity of CH do not necessarily coincide with improved in vivo antiplaque efficacy.

Evidence is presented which shows that Strep. mitior and Strep. mutans (which are unable to metabolize xylitol) take yp xylitol and transfer it to xylitol phosphate. Dental plaque also takes up xylitol. In this case a xylitol/protein complex is formed in addition to xylitol phosphate and also some labelled components yet to be identified. It is suggested that accumulation of xylitol phosphate inside the cells may "poison" the bacteria and possibly explain the caries therapeutic effect of xylitol observed in some laboratories.

Teeth have previously been shown not to be of any major importance when quantitatively measuring the retention of chlorhexidine in the oral cavity. Only a few studies have examined the significance of the binding of chlorhexidine to the tongue in relation to its plaque inhibiting effect. The present study was therefore carried out to further examine these possible chlorhexidine receptor sites in the oral cavity in relation to its known antibacterial effect at the teeth surface. Two daily applications of chlorhexidine on the teeth in the right side of the maxilla, against a contralateral water control, both in combination with a sucrose challenge six times daily, showed no significant reduction of plaque formation when compared to an application of sucrose used alone. Two daily applications of chlorhexidine on the tongue, again combined with sucrose challenge, also showed no significant plaque inhibiting effect. The results obtained indicate that neither the teeth nor the tongue seem to be of major importance as receptor sites for chlorhexidine in the oral cavity as related to its observed clinical effect.

Hydroxyapatite treated with fluoride containing both alkali soluble fluoride (CaF2) and alkali stable fluoride (FAp) was shown to take up less albumin than hydroxyapatite but more lysozyme. The affinity of the adsorption of albumin to fluoride treated apatite was increased, whereas no difference was demonstrated in the affinity of lysozyme. Tooth surfaces in vivo contain both calcium fluoride and fluoroapatite. Protein adsorption to mixed phases may thus have clinical significance.

Xylitol has previously been shown to inhibit acid production in vitro when glucose is used as energy source, and the present studies were carried out to investigate whether this effect was valid in vivo. A solution containing both xylitol and glucose was applied on sucrose-induced 4-day-old plaque in vivo. The xylitol added to the glucose solution inhibited the acid production in the plaque, measured as a drop in pH, compared to using glucose alone. A further reduction in acidogenicity was obtained when xylitol was used as a rinse for 1 hr continuously prior to the glucose challenge.

The effect of SnF2-treatment of dentin surfaces was investigated by means of scanning electron microscopy (SEM) and electron microprobe analysis. Human dentin was treated with aqueous SnF2 solutions of concentrations varying from 1 to 10%. The treatment periods lasted for 1, 5, 10, or 60 min. Both tin and fluoride were identified on the surfaces. The concentration varied depending on the extensiveness of the treatment. Immersion in 1 M KOH for 15 h removed both tin and fluoride from the surfaces. This reaction was not observed after immersion in H2O for the same time period. Examination of the SnF2-treated dentin surfaces showed a dense layer of globular particles and in addition some larger particles. The dentinal tubules were totally covered even after the treatment with the lowest concentration of SnF2. Deposition of tin- and fluoride-containing globules on dentin surfaces may be of clinical interest. This layer may have importance both for the caries resistance of dentin and for hypersensitivity reactions.

Extrinsic discoloration of teeth following a large consumption of tannin-containing beverages or a prolonged use of chlorhexidine mouthrinses is a well known observation. Tannins as well as chlorhexidine are denaturing agents. Based on preliminary studies revealing the presence of iron in chlorhexidine discolored pellicle material, the ability of iron to stain the integument after pretreatment with the two denaturants was studied in a human model. The denaturing effect of an acidic environment was also included. Enamel slabs fixed to acrylic appliances were carried in the oral cavity and alternately exposed to the test solutions in different sequences in vitro. Pretreatment with chlorhexidine or tannic acid led to marked discoloration upon iron application during 5-d tests, whereas the compounds individually had no such effect. A large content of the metal was found in the stained material. Stannous fluoride appeared to reduce the formation of the pigments, and strong oxidation completely bleached the established color. Possible mechanisms underlying the phenomena observed are discussed.

Demineralization of enamel was induced by applying orthodontic bands in 15 patients having two of their premolars extracted for orthodontic reasons. After a 4-wk caries induction period, eight patients were instructed to rinse their teeth once daily with a neutral 0.05% NaF solution, whereas seven patients received a single treatment with a neutral 2% NaF solution. The bands were reattached to the teeth during the fluoride treatment period and the teeth were extracted after two more weeks. Three consecutive enamel layers were etched off, and a significant uptake of fluoride in all three layers were found in both treatment groups. A larger part of the deposited fluoride was retained in an alkali insoluble form (i.e. fluorapatite) compared with previous studies of sound enamel. It is suggested that the chemical conditions in the cariogenic milieu were favorable for transformation of the fluoride into a stable apatite structure.

The supernatant of centrifuged whole saliva was incubated with radiolabeled sucrose to measure polysaccharide production by cell free transferases and to examine whether water-insoluble polysaccharides were produced. Amounts of polysaccharides were considered to reflect the level of cell free transferases in saliva. Plating samples on blood agar, MS and MSB plates gave salivary counts of total CFU, total streptococci, S. salivarius and S. mutans. The capability of the cell free portion of saliva to produce polymers was confirmed and it appeared that the cell free transferases were able to produce water-insoluble polysaccharides. Significant correlations were found between the total and the insoluble polysaccharides from 14C-G'-sucrose and total CFU, total streptococci, S. salivarius and S. mutans, respectively. Heavily S. mutans infected subjects seemed to produce particularly large amounts of water-insoluble polysaccharides from 14C-G'-sucrose. The apparently water-insoluble 14C-F'-polysaccharides correlated significantly to the number of S. salivarius. It was thus concluded that the constitution of the oral microflora and particularly the levels of S. mutans and S. salivarius were of importance for the level of cell free transferase activity.

In a previous study we demonstrated that gingival health could be maintained in a group of highly motivated nurses using a dentifrice containing a zinc salt and triclosan. We have now investigated the effect of the experimental dentifrice on a group of less motivated men. One hundred and three male students were given oral hygiene instruction (OHI) and their teeth were professionally cleaned. For each individual, both the instruction and cleaning were completed in a single 15-min period. Two balanced groups were formed, based on the prestudy plaque levels and gingival bleeding. One group used the experimental dentifrice for 12 months, while the other used a control. Results were assessed after 6 months, and after 12 months. As a result of the OHI, plaque and gingival bleeding were reduced at the end of the prestudy period. This improvement was not maintained by the control group even for 6 months. In contrast, the test group exhibited significantly lower plaque levels and higher standard of gingival health throughout the 12 months. Reassessment of available participants 6 months after the study showed that gingival health in both groups had returned to its prestudy condition. The lower observed standard of gingival health in the test group after ceasing to use the experimental dentifrice further supports the conclusion that this dentifrice can contribute to an oral care program.

The in vivo effect of some cations on the amount of lipoteichoic acid (LTA) formed in plaque was investigated in two studies. In the first part five students followed six mouthrinsing programs, each of which lasted 4 d. Rinsing was performed for 1 min every second hour with a test solution (0.05% stannous fluoride (SNF2); 0.05% chlorhexidine gluconate; 0.3% lanthanum chloride (LaCl3) and 0.05% sodium fluoride (NaF), followed 5 min later with a rinse of a 15% sucrose solution. Sucrose alone and xylitol rinses were used as controls. The second part involved a group of 10 students rinsing for 1 week four times daily with a sucrose solution, and for another week four times daily with the same source sucrose solution and in addition, three times daily with a 0.05% SnF2 solution. The individual plaque samples were collected after each rinse program, made into a suspension and then divided for protein analysis, carbohydrate analysis and estimation of LTA by phenol extraction and indirect hemagglutination against a specific antiserum. The total amount of plaque formed and the LTA content were reduced in sucrose plaque by the chlorhexidine and SnF2 rinse programs, or when xylitol replaced sucrose as the main sugar source. There was no significant effect with LaCl3 or NaF. The rinse produced changes in the clinical appearance of the plaque.

Mouthrinses with SnF2 in 11 subjects significantly reduced (P less than 0.01) the total colony forming units (CFU) count and the numbers of Streptococcus mutans and Streptococcus sanguis in plaque. The numbers of S. mutans and S. sanguis were significantly more reduced than was the total CFU count. After rinsing with SnF2S. sanguis was present in 97% and S. mutans in only 42% of plaque samples from tooth surfaces where they were detected after rinsing with water. SnF2 also significantly reduced (P less than 0.01) the number of S. mutans in saliva. Mouthrinses with NaF did not markedly affect the number of S. mutans either in plaque or in saliva.

Addition of 5% xylitol to growing cultures of Streptococcus mutans OMZ 176 reduced the amount of extractable glycerol-phosphate polymers in these cells compared to S. mutans cultures grown in medium with 5% glucose added. The glycerol-phosphate polymers were extracted from the cells by hot phenol-water-extraction, and separated by column chromatography. Lipoteichoic acid (LTA) was identified by indirect haemagglutination tests and lipid analysis. The amount of LTA extracted from the cells or present in the medium was not significantly different. It is suggested that the accumulation of intracellular xylitol-phosphate observed in a previous study causes an effect similar to glucose starvation, which is known to affect the composition of the cell wall.

The sulphated rabbit salivary glycoprotein had a high affinity for hydroxyapatite in vitro and could be eluted by phosphate buffer, pH 6.8. Such substances may have an enamel-protecting effect by providing an organic matrix for repair and remineralization of the tooth surface.

IgA, IgG, albumin, lysozyme, alpha-amylase and glucosyltransferase were identified in the saliva coat which forms on hydroxyapatite exposed to whole saliva. It is suggested that these proteins may be involved in binding microorganisms to saliva coated hydroxyapatite in model studies.

The present study showed that the pancreas of two monkey species contained sulphated blood-group substance. Such strongly anionic molecules are known to bind calcium, and their solutions form gels in the presence of cations. It is suggested that such a mechanism may be involved in cystic fibrosis.

Fluoride acquisition during topical fluoride treatment was studied after different time intervals, at different concentrations and at different pH. The effects of pretreating the enamel with Ca++, and of pre-etching were also tested. Four experimental groups of repeated measures design were established. Chemical assessments were made of the amounts of fluoride formed on (as alkali soluble fluoride, i.e., calcium fluoride) and in enamel (as firmly bound fluoride). The depositions on enamel were also demonstrated by SEM. The amounts of alkali soluble fluoride on enamel increased with time, concentration, pH-decrease and calcium availability. The time of exposure seemed to be the major factor. The amounts of fluoride deposited on enamel outranged by far (greater than 70%) the amounts of fluoride acquired in the enamel. The formation of alkali soluble fluoride on enamel is probably limited by the availability of calcium ions. It is suggested that the fluoride on enamel may protect the enamel surface and serve as a reservoir of fluoride.

Some aspects of the cariogenicity of sucrose are discussed, in particular the data indicating that glucosyltransferase (GTF) mediates the well known stickiness of sucrose exposed S. mutans and plaque in vivo. The non-sucrose dependent colonization of teeth, which has been studied extensively, is judged to be of less importance because S. mutans is only pathogenic in combination with sucrose. Strong evidence from several laboratories show that free GTF is present in saliva and that it adsorbs to the pellicle and is able to form glucan in the adsorbed state. Glucan-glucan interaction between 1-3 linked glucans gives a strong sucrose dependent interaction between glucan chains originating from the GTF adsorbed to the pellicle and from GTF on the bacterial surface.

The present study showed that S. mutans and S. sanguis behaved like negatively-charged particles in their interaction with hydroxyapatite in vitro. Phosphate in the system inhibited bacterial uptake by apatite, whereas calcium increased the uptake. A layer of acidic protein inhibited the uptake of bacteria by hydroxyapatite. The opposite was true when a basic protein was first adsorbed to the apatite. A saliva film on the apatite decreased the uptake of bacteria, supporting the view that acidic proteins are selectively adsorbed by hydroxyapatite from saliva. The results indicate clearly that electrostatic forces may be involved in bacterial interaction with tooth surface.

Experiments in a standardized rabbit model indicate that the yellow-golden stain formed on tooth surfaces during the use of SnF2 may consist of stannic sulfide. The nature of the stain, the presence of sulfur in the samples and the effect of an oxidizing agent on the stain support this view. It is suggested that the low pH of SnF2 caused denaturation of pellicle protein with exposure of sulfhydryl groups, which later form stannic sulfides through reactions with the stannous ions present in the preparations.

The aim of the present study was to compare the resistance of fluoroapatite (shark enamel) and hydroxyapatite (human enamel) against a high caries challenge in a human in vivo model. Two samples of shark enamel and human enamel were each placed in removable appliances in six children and carried for 1 month and a plaque retentive device was placed over each enamel sample. The results showed that the mean total mineral loss (delta Z) was 1680 vol% micron in human enamel and 965 vol% micron in shark enamel. The corresponding mean values for lesion depth were 90 micron and 36 micron, respectively. It is concluded that even shark enamel containing 30,000 ppm F has a limited resistance against caries attacks.

The experiments showed that a part of the fluoride which was taken up by hydroxyapatite or teeth at low concentrations of fluoride at neutral pH was soluble in alkali (IN KOH, 24 h) and was thus not fluoroapatite. Calcium fluoride could not form under the present conditions because the solubility of this compound was not exceeded. It is suggested that the alkali soluble fluoride is adsorbed to calcium ions bound as counterions in the hydration layer of the hydroxyapatite or the enamel. This is consistent with previous findings in this laboratory, showing that fluoride displaced acidic proteins adsorbed to calcium receptors on the hydroxyapatite surface in the same way as other anions displace proteins. It could also be shown that polyanions and polycations adsorbed to hydroxyapatite surfaces by ionic exchange, displacing phosphate or phosphate and calcium respectively in the process. A model is suggested which differs slightly from that proposed by Bernardi.

The effect of xylitol, NaF, or ZnCl2 on the ultrastructure of Streptococcus sobrinus OMZ 176 was studied. The bacteria were grown statically in air for 8 h in brain-heart infusion broth supplemented with 33 mM Xylitol, 2.5 mM NaF, 0.5 mM ZnCl2, separately or in combination. The bacteria were washed briefly and prepared for scanning and transmission electron microscopy. All three agents and their combinations induced distinct ultrastructural alterations. The alterations were related to various aspects of cell morphology and varied in nature and extent among the agents. The most pronounced ultrastructural alterations were seen in bacteria grown in the presence of zinc ions. At the concentrations used, fluoride appeared to induce the least effect.

This study showed that pyrophosphate (PP) desorbed an acidic protein (albumin) from hydroxyapatite (HA) more effectively than phosphate and that HA pretreated with PP took up markedly less protein than untreated HA. The protein which adsorbed to PP-treated HA was more loosely bound than that adsorbed to untreated HA. In vivo experiments showed that pellicle formed more slowly on PP-treated etched enamel than on untreated controls. The possible clinical implications of these findings are discussed.