Insoluble zinc, cupric and tin pyrophosphates inhibit the formation of volatile sulphur compounds.

Oral malodour is mainly a result of the production of volatile sulphur compounds (VSC). The present study was concerned with investigating the anti-VSC effect of insoluble pyrophosphates (PP) of zinc, copper(II) and tin(II). The hypothesis to be tested was that the sulphide anions produced when VSC are solubilized in water have a higher affinity for the respective metal ions than the PP anion. The anti-VSC effects of insoluble PP were compared with the corresponding soluble metal salts using three in vitro methods: saliva putrefaction; dialysis of a suspension of PP and saliva against water; and analysis of water containing hydrogen sulphide and methyl mercaptan gases, and gases in the headspace. The levels of VSC were analysed by gas chromatography in the first and third methods, and released metal ions were analysed by atomic absorption spectroscopy in the second. The results showed that: the insoluble metal PP inhibited VSC formation in saliva by 99-100%; under dialysis, only minute amounts of metal ions are released from the combination of PP and saliva; and the PP lost their metal cations in water containing dissolved gases and inhibited VSC formation. Hence, the results support the experimental hypothesis. Sulphide ions are obviously very strong ligands for these metal ions.

Effects of metal salts on the oral production of volatile sulfur-containing compounds (VSC).

BACKGROUND/AIM: Halitosis, mainly caused by bacteria located on the posterior dorsum of the tongue and in periodontal pockets, is due to formation of volatile sulfur compounds (VSC). The hypothesis to be tested was that the affinity of a metal for sulfur determines its anti-VSC activity. METHOD: Clinical tests were carried out on 12 subjects who rinsed with cysteine to induce halitosis (baseline) before rinsing with 7.34 mM ZnCl2, SnF2 and CuCl2. Mouth air VSC analyses were repeated following cysteine rinses at 1 h, 2 h and 3 h using a gas chromatograph. In vitro experiments tested toxic metals Hg2+, Pb2+ and Cd2+. 10-microl aliquots of metal salts were added to 1-ml aliquots of human whole saliva from 30 subjects. Samples were incubated overnight at 37oC and saliva headspace was analyzed for VSC in a gas chromatograph. CLINICAL RESULTS: Cu2+>Sn2+>Zn2+ (supports hypothesis). Zn2+ had significantly less anti-VSC effect compared with Cu2+ and Sn2+ at 1, 2 and 3 h. In vitro results indicated that Hg2+, Cu2+ and Cd2+ had close to 100% anti-VSC effect, and that Pb2+ was less effective and Cd2+ more effective than expected in inhibiting VSC. CONCLUSIONS: Apart from Hg2+ and Cu2+, the metals had a significantly greater effect on H2S than on CH3SH. Cu2+ and Hg2+ have well-known antibacterial activity and may presumably also operate by this mechanism.

On the transformation of sulfur-containing amino acids and peptides to volatile sulfur compounds (VSC) in the human mouth.

Halitosis is most often caused by oral conditions. Volatile sulfur compounds (VSC), constituting the major components of oral malodor, are produced by anaerobic, gram-negative bacteria retained mainly in periodontal pockets or on the tongue dorsum. Sulfur-containing amino acids serve as substrate for these bacteria. VSC have also been found to have unfavorable effect on the tissue. The aim of this study was to examine whether normal, healthy individuals with no history of halitosis were able to produce VSC from cysteine, when applied as a mouthrinse. A further aim of the study was to investigate and compare the potential of other sulfur-containing amino acids and peptides as substrates for oral VSC production and to localize the odor-production sites. A portable sulfide monitor was used for VSC registration. Results showed that all test subjects produced high oral concentrations of VSC upon rinses with cysteine, which thus seems to be a major substrate for VSC production. The other sulfur-containing substrates had much less effect. It was found that the tongue was the major site for VSC production, and that saliva per se caused low VSC production.

The effect of some metal ions on volatile sulfur-containing compounds originating from the oral cavity.

Halitosis originates mainly from the oral cavity, and the volatile sulfur-containing compounds (VSC) are the major contributors of the unpleasant odor. Anaerobic G- bacteria use sulfur-containing amino acids in their production of VSC. Zinc has been shown to inhibit production of odiferous VSC, and the mechanism proposed has been that zinc, with its affinity for sulfur, oxidizes thiol groups and thereby inhibits the precursors of VSC. The aim of the study was to investigate whether, and to what extent, other metal ions with affinity for sulfur exert the same effect and whether a correlation exists between the sulfur affinity and VSC-inhibiting activity of these metals. VSC levels were measured on the 'morning breath' of 10 test subjects, using a portable sulfide monitor. The mouthrinses tested were aqueous solutions of zinc chloride, zinc citrate, stannous fluoride, cuprous gluconate, ferrous gluconate, and silver acetate, and they contained equimolar amounts of metals (1.47 mmol/I). The results showed that the ranking of Zn++ and Sn++ differed in the clinical test compared with sulfur affinity, and likewise with Ag+ and Fe++. It may therefore be concluded that there is no positive correlation between the inhibiting effect of metal ions on VSC and their affinity for sulfur.

The effect of zinc-containing chewing gum on volatile sulfur-containing compounds in the oral cavity.

Volatile sulfur-containing compounds (VSC) are known to constitute the major component of halitosis. Aqueous solutions of zinc salts have been shown to reduce the levels of VSC produced orally. The aim of the present study was to examine whether zinc could be made available in the oral cavity and inhibit VSC production when delivered by a chewing gum. VSC measurements were carried out on the 'morning breath' of 11 test subjects and re-examined after the use of test solutions containing 0.02% zinc chloride, 0.2% chlorhexidine, or water or the use of chewing gums containing 2 mg, 0.5 mg, or 0 mg zinc acetate. The results showed that similar amounts of zinc in mouthrinses or chewing gum had the same effect, with a reduction of the oral VSC of 45%. Chewing gum thus seems to be a viable alternative for delivering zinc to reduce VSC levels in the oral cavity.

[Bad breath from the oral cavity]. / Dårlig ånde fra munnhulen.

Halitosis, or bad breath, is a clinical problem for many people. In the majority of cases the problem has been shown to originate in the oral cavity. All conditions that favour the retention of anaerobic, mainly gram-negative, bacteria will predispose for the development of bad breath. In addition to periodontal pockets, the most important retention site is the dorsum of the tongue with its numerous papillae. The bacteria metabolize sulphur-containing amino acids to yield the volatile sulphur-containing compounds hydrogen sulphide and methylmercaptane. These substances have an offensive odour in very low concentrations. The sulphur compounds may also damage the surrounding tissue directly, and thereby contribute to the initiation and development of periodontal disease. During the night and between meals the conditions are optimal for odour production. The importance of regular meals is therefore emphasized. To supplement conventional oral hygienic measures the patients are advised to brush their tongue. The use of oral care products which contain metal ions, especially zinc, will inhibit odour formation because of the affinity of the metal ion to sulphur. It is also possible to measure the level of volatile sulphur-containing compounds in the air in the mouth directly by means of a portable sulphide monitor. Dentists and physicians are both advised to discuss the problem of halitosis with their patients, since this should be regarded as an important aspect of the patient's health.

Are sodium lauryl sulfate-containing toothpastes suitable vehicles for xylitol?

The hypothesis to be tested in this study was that toothpastes containing sodium lauryl sulfate (SLS) is unsuitable vehicles for xylitol. The bacteriostatic (and cariostatic) effect of xylitol is assumed to be caused by intracellular accumulation of xylitol-5-P in plaque bacteria. Experiments were designed to investigate whether presence of SLS would affect the uptake of xylitol by interacting with the bacterial membranes and thus inhibit xylitol-5-P formation. It was shown in an in vitro study that even very low concentrations of the strong anionic detergent SLS inhibited uptake of xylitol and xylitol-5-phosphate formation by dental plaque totally. The mild nonionic detergent ethoxylated stearyl alcohol (30x EO) had no such effect. In vivo experiments with toothpastes containing xylitol and either the strong or the mild detergent, showed that xylitol in toothpaste with SLS was not available for the plaque bacteria and gave no adaptation to xylitol, whereas in the presence of 30x EO it was available, and a xylitol adaptation was observed. Glucose metabolism, which was also studied for the plaque samples, was not significantly affected by presence of any of the 2 detergents, indicating that the amounts of xylitol in toothpastes were presumably too low to give clinical significant effects, even when mild detergents are used.

Xylitol fermentation by human dental plaque.

The aim of the present study was to examine xylitol metabolism by dental plaque collected immediately after the use of xylitol gum. Plaque was collected from 12 individuals immediately before and after xylitol exposure. The effect on xylitol metabolism by dental plaque of a 3 d discontinuation of the xylitol exposure was also examined. Xylitol metabolism by the plaque suspensions was initiated by adding [14C]xylitol and analyzed by HPLC. The results showed increased xylitol metabolism after 11 wk of chewing xylitol-containing gum. The ability to metabolize xylitol was rapidly reduced after the discontinuation of the xylitol exposure. It is suggested that an induction of enzymes in one or more of the species of plaque bacteria may have caused this effect. Glucose metabolism, which also was studied in the plaque samples, was decreased after xylitol exposure, but increased again 3 d after cessation of the xylitol exposure. It is suggested that the reduced glycolysis was caused by accumulation of intracellular xylitol-5-phosphate in some plaque bacteria during the xylitol exposure.

Xylitol 5-P formation by dental plaque after 12 weeks' exposure to a xylitol/sorbitol containing chewing gum.

Five subjects used xylitol-containing chewing gum for 12 wk. Dental plaque was collected before and after the exposure to xylitol. The plaque samples were examined for their capacity to form xylitol 5-P by incubation with 14C labeled xylitol, extraction and separation on HPLC. It was found that the capacity of the plaque to form xylitol 5-P was not reduced during the xylitol exposure in any of the subjects. No other xylitol-derived metabolites were observed. The inhibitory capacity of xylitol thus appears to be maintained after 12 wk exposure to xylitol.

[Xylitol, mechanisms of action and uses]. / Om xylitol, dets virkningsmekanismer og anvendelse.

Xylitol is recommended as a sugar substitute and is claimed not only to be non-cariogenic, but also to exhibit an anti-caries effect. An interesting aspect of xylitol is that it has a certain bacteriostatic effect. Xylitol is taken up by many strains of Strep mutans and Strep sanguis even if these organisms are unable to metabolize xylitol. It enters the bacteria by the phospho-transferase system. Xylitol-phosphate inhibits the glycolysis probably at the phosphofructokinase level, and is also de-phosphorylated and expelled through a "futile cycle". The combination xylitol and sorbitol is particularly interesting, since xylitol inhibits the metabolization of sorbitol by Strep mutans and sorbitol also appears to potentiate the bacteriostatic effect of xylitol. Furthermore the combination is favourable from an economical point of view since sorbitol is less expensive than xylitol. Xylitol induces diarrhea if consumed in considerable amounts and is thus only suitable in products like chewing gum and tablets.

The effect of xylitol on plaque metabolism.

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.

Effect of xylitol on dental plaque in vivo during carbohydrate challenge.

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.

Effect of chlorhexidine and lanthanum on plaque formation.

The present study included rinses with aqueous solutions of lanthanum prior to and after traditional chlorhexidine mouthrinses. Lanthanum has an extremely high affinity for phosphate, and the experiments were designed to examine the role of this anion as a receptor site for chlorhexidine in the oral cavity. The results indicate that from 1/3 to 1/2 of the chlorhexidine retained in the oral cavity may be bound to phosphate groups.

Further studies on the growth inhibition of some oral bacteria by xylitol.

The growth in Brain Heart Infusion medium containing glucose or sucrose of Streptococcus mutans strain OMZ 176, two strains of Strep. sanguis (ATCC 10556 and No. 39) and Actinomyces viscosus type ATCC 27044 was inhibited by xylitol but not by D-arabitol or ribitol. When fructose was substituted for glucose, xylitol had no growth-inhibiting effect. It was also shown that the bacteria produced less acid in the presence of xylitol, as measured by the pH of the cultures or by neutralization with alkali.

Comparison between plaque inhibiting effect of chlorhexidine and aqueous solutions of copper- and silver-ions.

Rinsing experiments with chlorhexidine, copper and silver solutions were performed in a group of volunteers. The plaque was measured after rinsing with the test solutions for 4 d and no mechanical oral hygiene allowed. Chlorhexidine and copper, both 1.1 mM solutions, gave reduced plaque scores, chlorhexidine being slightly more effective than copper, but the difference was not statistically significant. A 1.1 mM solution of silver nitrate also showed a plaque inhibiting effect, statistically significant from the placebo, but the effect was also significantly less than when chlorhexidine or copper were used. Copper ions may be of clinical interest because this is an essential metal in human nutrition with low toxicity.

Plaque inhibiting effect of combinations of chlorhexidine and the metal ions zinc and tin. A preliminary report.

Rinsing experiments with combinations of chlorhexidine, zinc- and stannous ions were performed in a group of students. Chlorhexidine and zinc (0.2% and 0.3% respectively) gave a plaque inhibiting effect slightly better than chlorhexidine alone, whereas chlorhexidine and stannous ions in the same concentrations showed a reduced effect, presumably due to the low pH of the solution. Pre-rinses with metal ions caused a marked reduction in the effect of chlorhexidine, whereas chlorhexidine first and metal ions afterwards gave approximately the same effect as chlorhexidine alone. The results indicate that the metal ions and chlorhexidine have the same receptor sites in the oral cavity, chlorhexidine exhibiting the stronger affinity when the ions were applied together.

Relationship of the sarcoplasmic reticulum to fibril and triadic junction development in skeletal muscle fibers of fetal monkeys and humans.

Examinations of stages of fibril development in muscle fibers of seven Rhesus monkey and six human fetuses reveal SR tubules encircling the Z lines at all stages of fibril development. The encircling SR tubules are continuous with the SR network of tubules which is found surrounding fibrils at all stages of development observed. The SR tubules encircling the Z lines show connections (electron-opaque strands) with the Z lines. The developing triadic junction shows a progressive increase in complexity of structures within the junction. First, membranes of T and SR become apposed with no visible structure between them- Second, tenuous connections are found traversing the space between apposed membranes. Third, well developed bridges are seen traversing the space. And finally, an intermediate density midway between the apposed membranes and parallel to them is found in favorable sections. Junctions between T tubule membranes were also observed and the structures in these junctions are somewhat similar to those found in junctions between T and SR membranes. The change in orientation of triads from predominantly longitudinal to predominantly transverse is complete in the 18-week monkey fetus and incomplete in the latest stage (28-week) of fetal development observed in humans.