Dowen Birkhed

Sugar Content, Acidity and Effect on Plaque pH of Fruit Juices, Fruit Drinks, Carbonated Beverages and Sport Drinks

The concentration of fructose, glucose and sucrose, the pH and the titratable amount of acid were analyzed in the following groups of soft drinks (8–11 samples per group): (1) fruit juices, (2) fruit

Acid production from Lycasin®, maltitol, sorbitol and xylitol by oral streptococci and lactobacilli

The acid production from maltitol was compared with the acid production from hydrogenated starch hydrolysate (Lycasin), sorbitol and xylitol by a number of oral strains and reference strains of Streptococcus mutans, S. sanguis, S. salivarius, S. mitior, S. milleri, S. faecalis, S. faecium, S. avium, Lactobacillus casei and L. salivarius. The polyols were added to a final concentration of 1.0% to two different basal media. Incubation was performed at 37 degrees C for 7 days after which the pH was recorded. Maltitol was fermented only by the lactobacilli (about two thirds of the strains). Lycasin was fermented by all strains of S. faecalis, more than 90% of the lactobacilli, about half of the S. sanguis strains, about one third of the S. mutans strains, and by a few other streptococcal strains. Acid production from sorbitol was observed among more than 80% of the S. mutans strains and the S. faecalis strains and most of the lactobacilli strains. Sorbitol-fermenting strains of S. sanguis and of S. mitior, all isolated from sorbitol-consumers, were observed. No other sorbitol-fermenting streptococci were found. Only the reference strains L. salivarius subsp. salivarius ATCC 11741 and S. avium ATCC 14025 fermented xylitol.

Structure of extracellular water-soluble polysaccharides synthesized from sucrose by oral strains of Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguis and Actinomyces viscosus.

Abstract Extracellular water-soluble polysaccharides produced from sucrose by various strains of oral streptococci and one strain of Actinomyces viscosus were isolated and analysed. Methylation analysis and characterization of the cleavage products by gas-liquid chromatogra-phy-mass spectrometry were the principal methods used. Streptococcus salivarius ATCC 9759, ATCC 13419 and NCTC 8618 and A. viscosus ATCC 15987 synthesized fructans of the levan-type with (2 → 6)-linked β-fructofuranoside residues, branched in the 1-position (15–17 per cent) and of high molecular weight (2.7 × 106 − 21.6 × 106). Strep. mutans strain JC2, however, produced a fructan, 12.4 × 106, of the inulin-type with (1 → 2)-linked β-fructofuranoside residues and with some branching in the 6-position (6 per cent). All glucans isolated from Strep. mutans strains JC2, FA1 and Ingbritt and Strep. sanguis strain 903 were of the dextran-type, predominantly (1 → 6)-linked, or to a lesser extent (1 → 3)-linked (9–12 per cent) with branching in the 3- and 6-position (19–23 per cent). Both high (12.4 × 106) and low molecular weight glucans (129,000–136,000) were found.

Salivary glucose clearance, dry mouth and pH changes in dental plaque in man.

The aim was to study the effect of different salivary secretion rates on glucose clearance in saliva and on pH changes in dental plaque in man. Eighteen dental students, 21-33 yr old, participated. Dry mouth was induced by injecting methylscopolamine-nitrate submucosally in the labial sulcus. When dry mouth was established, two variables were measured at 1 h intervals, while the salivary flow was recovering: (1) secretion rate of resting and paraffin wax-stimulated whole saliva, and (2) glucose clearance in saliva after ingestion of a glucose tablet. pH changes in dental plaque were studied in 9 of the 18 subjects after a mouth rinse with 10% glucose at two separate occasions, once before and once after an injection of methylscopolamine-nitrate. Higher glucose concentration levels in saliva were found at low than at normal salivary secretion rate. After logarithmic transformation of the salivary glucose concentration values, a biphasic elimination pattern could be seen, with a steeper initial phase followed by a slower one. A critical value for the secretion rate with respect to the salivary glucose clearance time was found to be 0.14 ml/min for resting and 0.62 ml/min for stimulated whole saliva (mean values). The pH changes in dental plaque after the mouth rinse with glucose at extremely low secretion rate were significantly more pronounced than at normal flow rate. Thus, salivary secretion rate affects both the glucose clearance in saliva and the pH changes in dental plaque in man.

Effect of Professional Flossing with Chlorhexidine Gel on Approximal Caries in 12- to 15-Year-Old Schoolchildren

The aim of the investigation was to evaluate the effect of chlorhexidine gel treatment on caries development of approximal tooth surfaces and on salivary counts of Streptococcus mutans. 220 12-year-old schoolchildren, divided into three groups, participated: (1) chlorhexidine gel group (n = 72), (2) placebo gel group (n = 77), and (3) control group (n = 71). The study was carried out double blind with respect to the two gel groups. Group 1 was treated 4 times/year with 1% chlorhexidine gel and group 2 with a placebo gel. Approximately 1 ml of gel was applied interdentally by means of a flat dental floss. The control group did not receive any gel treatment or flossing. Number of S. mutans in the saliva was estimated on five occasions during the study with the spatula method. After 3 years, the mean approximal caries increment, expressed as new DFS, was 2.50 in the chlorhexidine gel group and 4.30 in the placebo gel group (p less than 0.05). The corresponding figure in the control group was 5.25 (p less than 0.001 when compared to group 1). 44% of the children in the chlorhexidine gel group and 32% in the placebo gel group did not develop any new approximal caries lesion during the 3-year observation period compared to 18% in the control group (group 1-3 p less than 0.001; group 2-3 p less than 0.05). The number of new approximal fillings (FS) was 0.24 in the chlorhexidine gel group, 0.75 in the placebo gel group and 0.82 in the control group (group 1-3 p less than 0.01; group 2-3 p less than 0.05). There was no statistically significant difference between the groups with respect to numbers of S. mutans in saliva. However, there were more individuals with low numbers of S. mutans in the chlorhexidine gel group at the final examination compared to the baseline level (p less than 0.05).

Effects of Partial Sugar Restriction for 6 Weeks on Numbers of Streptococcus mutans in Saliva and Interdental Plaque in Man

Twenty 17-year-old schoolchildren were selected for the study because of high salivary counts of Streptococcus mutans ( > 106 CFU/ml) and a frequent intake of sugars between meals. After a baseline determination of the numbers of S. mutans and lactobacilli in saliva, and of S. mutans in interdental plaque, the subjects were asked to avoid sugar-containing between-meal products, e. g. sweets, chewing gum, soft drinks and confectionery, and to eat a maximum of 4–5 meals/day. After 6 weeks of sugar restriction, the participants were allowed to return to their former food habits and were then followed for a further 6-week period. Seven subjects, also with high salivary counts of S. mutans and a frequent sugar consumption, served as control group. The results showed a statistically significant decrease of mean salivary S. mutans counts from 1.5 × 106 to 0.3 × 106 CFU/ml (p 4 to 0.2 × 104 CFU/ml (p S. mutans were reduced from 52 to 32% (p S. mutans and lactobacillus values almost reached the baseline level again. No obvious changes were found in the control group for any of the studied variables. To conclude, the 6-week period with sugar restriction reduced the number of S. mutans both in saliva and in interproximal spaces. Also the lactobacillus counts in saliva decreased.

Effects of 3 months frequent consumption of hydrogenated starch hydrolysate (Lycasin®), maltitol, sorbitol and xylitol on human dental plaque

Lozenges containing hydrogenated starch hydrolysate (Lycasin), maltitol, sorbitol or xylitol were consumed 4 times daily during 3 months by 4 groups of persons (in all 85 subjects). In the maltitol-, sorbitol- and xylitol-group the plque wet weights were of the same magnitude before and after the test period. In the Lycasin-group, a higher value was found after than before the 3-month period (p less than 0.01). The acid production in suspensions of dental plaque material from Lycasin, maltitol and sorbitol expressed as per cent of that from glucose was approximately the same before and after the test period. From xylitol no acid production could be demonstrated either before or after the 3-month period. There were no statistically significant differences between the plaque pH-changes induced by rinsing with 50% solutions of Lycasin, maltitol, sorbitol or xylitol before and after the test period. However, there was a tendency (p less than 0.05) towards lower pH-values induced by the maltitrol and sorbitol rinse after the 3-month period compared with before. No difference in the relative numbers of facultative anaerobic streptococci. Streptococcus mutans or facultative anaerobic lactobacilli before and after the test period was found.

Sorbitol Adaptation of Dental Plaque in People with Low and Normal Salivary-secretion Rates

Caries-related bacteriological and biochemical factors were studied in 12 persons with low and 11 persons with normal salivary-secretion rates before and after a four-week period of frequent mouthrinses with 10% sorbitol solution (adaptation period). After the adaptation period, an increase in total numbers of sorbitol-fermenting bacteria and mutans streptococci was found in plaque samples from both groups. The pH drop in dental plaque in situ after a mouthrinse with sorbitol was more pronounced after the adaptation period, especially in the group with the low salivary-secretion rate. Increased acid production in plaque from sorbitol was also observed in the two groups in vitro. The composition of the fermentation end-products was affected by the sorbitol exposure. It is suggested that in subjects with diminished natural protection against caries development, such as patients with low salivary-secretion rate, a cariogenic potential of sorbitol should be considered when this polyol is included in products that might be used frequently.

Gas-liquid chromatographic analysis of amino acids in pellicle formed on tooth surface and plastic film in vivo

Abstract The amino acid composition of 2-h-old pellicle formed in vivo on tooth enamel and on plastic film (polyvinylchloride/polyvinylacetate) applied on tooth surfaces was studied. For comparison, saliva samples were analysed. On 5 consecutive mornings, the plastic film was applied on the buccal surfaces of 12 teeth in each of 4 subjects. After 2 h, the films were removed and material from the buccal surfaces of the 12 contralateral teeth was scraped off with a curette and pooled with material collected in the same way in the afternoon. A sample of whole unstimulated saliva was collected in the afternoon. After acid hydrolysis, N-trifluoro-acetyl-n-butyl derivatives of the amino acids were analysed by gas-liquid chromatography. The amount of protein in the pellicle samples (20–300 μg in the hydrolysates) allowed analysis to be performed well above the detection limit of the method. Thirteen amino acids were separated; the predominant ones in the film samples were in order: glutamic acid, glycine, aspartic acid, leucine and serine, and in the tooth samples: glutamic acid, glycine, serine, aspartic acid, leucine. Between film and tooth samples, statistically significant differences were observed in the amounts of glycine, isoleucine, serine and lysine. In the saliva samples, the predominant amino acids were in order: glutamic acid, glycine, proline, aspartic acid and leucine. Tyrosine and phenylalanine were in small amounts in all samples.

Acid production from sorbitol in human dental plaque

Acid production from glucose and sorbitol in dental plaque suspensions and the pH changes in dental plaque in vivo after mouth rinses with 10 per cent solutions of glucose and sorbitol were studied before and after 4–6 weeks of frequent daily mouth rinses with sorbitol in 18 subjects. The mean acid production from sorbitol, in per cent of that from glucose, increased about 21 per cent (p < 0.001) and mean initial (resting) plaque pH values were approximately 0.2 units higher (p < 0.01) after the sorbitol adaptation period. The pH-decreases from sorbitol were significantly more pronounced after the 6-week adaptation period (p < 0.01). Acid production activity from sorbitol and the pH-decreases after mouth rinses with sorbitol were considerably smaller than the corresponding values found with glucose before as well as after the adaptation period.