Fermentation of sugars and sugar alcohols by plaque Lactobacillus strains.

OBJECTIVE: The objective was to analyse the ability of Lactobacillus strains isolated from supragingival plaque of subjects with hyposalivation and from healthy controls to ferment sugars and sugar alcohols. MATERIAL AND METHODS: Fifty strains isolated from interproximal plaque from subjects with radiation-induced hyposalivation (25 strains), subjects with primary Sjögren's syndrome (16 strains) and from subjects with normal salivary secretion rate (9 strains) were tested. Growth and pH were determined after 24 and 48 h of anaerobic incubation in vials containing basal media with 1 % of glucose, fructose, sucrose, mannitol, sorbitol or xylitol. RESULTS: No differences between strains isolated from hyposalivated subjects and controls were detected. All strains lowered the pH to <5.0 from fructose and the majority of the strains from glucose and sucrose. A pH of <5.5 was seen for 52 % of the strains using mannitol, 50 % using sorbitol and 36 % using xylitol. The ability to produce acids from sugars and sugar alcohols was highest among strains of Lactobacillus rhamnosus, Lactobacillus casei and Lactobacillus paracasei and lowest among Lactobacillus fermentum strains. CONCLUSION: A large number of Lactobacillus strains are able to ferment not only sugars but also the sugar substitutes mannitol, sorbitol and xylitol to pH levels critical for enamel demineralisation. CLINICAL RELEVANCE: Our findings suggest that products containing mannitol, sorbitol and/or xylitol may contribute to the acidogenic potential of the dental plaque and especially in hyposalivated subjects with high numbers of lactobacilli.

An update on minor salivary gland secretions.

In this article, the literature on minor salivary gland secretion rates, composition, and function is reviewed. Measurements of the minor salivary gland secretion rates and composition are complicated, and the secretions display large biological variability. Despite this, some characteristics of these secretions have been found repeatedly in independent investigations. Minor gland saliva varies between different oral sites. Buccal saliva flow is higher than labial saliva flow, which in turn is usually higher than the palatal gland secretion rate. It is generally agreed that minor gland saliva is important for the whole saliva composition, and especially for the secretory immunoglobulin A and mucins. The secretion from these glands seems also important for subjective feelings of dry mouth and general wellbeing. Further research is essential for understanding the role of these secretions for oral, as well as for general, health.

Lactobacillus species in supragingival plaque in subjects with hyposalivation.

UNLABELLED: The aim of the study was to analyse the frequency of different Lactobacillus species in relation to the pH-lowering potential of the plaque. METHODS: Ten subjects with radiation-induced hyposalivation (RT group) and 10 subjects with primary Sjögren's syndrome (pSS group) and matched controls with normal salivary secretion were included. Lactobacillus species were selected from their growth on Rogosa agar and identified by PCR and restriction fragment length polymorphism using HaeIII and HpaII restriction enzymes. RESULTS: Lactobacilli were isolated from 14 subjects (6 RT, 3 pSS, 5 controls). The most prevalent species were Lactobacillus fermentum (7 subjects), Lactobacillus casei (7 subjects) and Lactobacillus rhamnosus (6 subjects). L. fermentum and L. casei were the most prevalent species in anterior sites and L. rhamnosus and L. fermentum in posterior sites. In anterior sites, hyposalivated subjects with high Lactobacillus counts had an increased plaque acidogenicity compared to those with low counts. In posterior sites, subjects with high Lactobacillus counts had a lower final pH compared with those with low counts. CONCLUSION: There were large intra- and inter-individual variations in frequencies of Lactobacillus species and Lactobacillus counts, but no specific species could be related to plaque acidogenicity.

Feeling of dry mouth in relation to whole and minor gland saliva secretion rate.

Previous reports indicate an association between whole saliva secretion rate and xerostomia, but the association is not always found in individuals complaining of dry mouth. In the present study, we hypothesised that the minor salivary gland secretions could affect subjective feelings of oral dryness in individuals with normal or low whole saliva secretion rate. 142 individuals, aged 18-82 years, participated in the study. Feelings of oral dryness were assessed separately for day- and nighttime by visual analogue scales. Resting and stimulated whole saliva flow rates were measured by conventional methods, and minor palatal, buccal and labial saliva secretion rates by the Periotron method. Twenty-three percent of the women and 15% of the men reported feelings of dry mouth during day and night. The results showed statistically significant lower resting and stimulated whole and minor labial gland saliva secretion rates in subjects reporting oral dryness during both day and night compared with non-complainers. In groups of individuals with normal simulated whole saliva secretion, those who complained from dry mouth both day and night had statistically significant lower labial secretion rate compared with those who had no complaints. Although not statistically significant, this difference was seen also in the groups with fewer individuals who had low whole saliva flow. In summary, our findings suggested that the labial gland saliva might affect subjective feelings of dry mouth both in individuals with normal and subnormal whole saliva flow.

Minor salivary gland secretion rates and immunoglobulin A in adults and the elderly.

Previously published data are conflicting about the effect of various factors on secretions from minor salivary glands. The aim of the present study was to investigate the secretion rate from palatal, buccal, and labial glands, and to analyze the immunoglobulin A (IgA) concentrations in relation to age, gender, circulatory disease, diabetes, medication, smoking, and pregnancy. Resting and stimulated whole-saliva secretion rates, as well as IgA concentration in stimulated whole saliva, were also examined. One-hundred and forty two individuals (96 women and 46 men), 18-82 yr of age, participated. The results did not suggest any effect of aging on the secretion capacity of minor salivary glands, but the IgA concentration seemed to increase with age. Women had lower buccal and labial saliva secretion rates, and lower levels of IgA in buccal saliva, than men. For whole saliva, resting, but not stimulated, saliva secretion rates were reduced with age, and the secretion rate of stimulated whole saliva was lower in women than in men. The IgA concentration in buccal saliva showed a positive correlation with IgA in stimulated whole saliva, and the IgA concentration decreased with increased flow rate in both salivas.

Minor salivary gland secretion in children and adults.

The minor salivary glands are of great importance in the physiology and pathology of the oral cavity. So far, studies of the minor glands have concentrated on adults. In the present study, minor salivary gland secretion was studied in the buccal and labial mucosa of 3-year-old children, adolescents and young adults. In addition, the number of glands per surface area was assessed in the labial mucosa. A total of 90 individuals were included, 30 in each age-group. Saliva was collected on filter paper discs and the salivary secretion rate was measured using a Periotron 8000. The number of secreting labial glands was assessed on PAS-stained filter paper discs under a microscope. Salivary secretion in the buccal mucosa was found to be age-related, with a statistically significant lower rate of secretion (P=0.003) in the 3-year-olds (mean 7.7 microl x cm(-2) x min(-1)) compared with the young adults (11.9 microl x cm(-2) x min(-1)). No significant differences between the sexes were noted. For the labial glands, no age- or sex-related differences were found. In all age-groups, salivary secretion was significantly higher in the buccal than in the labial mucosal area. A statistically significant difference in number of secreting glands was found between all age-groups, with a decreasing number of glands per surface unit with age. The number of glands was significantly lower in males compared with females in the group of adults. The lower rate of buccal salivary secretion in the young children may imply that the oral mucosa is more vulnerable to external injury and that caries protection on the buccal molar surfaces is lower. Previous studies indicate that adults with a reduced rate of minor salivary gland secretion are more susceptible to caries.