A method for measuring secretions from the palatal minor salivary glands

Sialometry of upper labial minor glands: a clinical approach by the use of weighing method Schirmer's test strips paper

Objectives. To establish referential values ranges of hyposalivation and normosalivation for the salivary flow rate (SFR) of upper labial (LS) and palatal (PS) mucosa using Schirmer's test strips paper and as a second goal to determine the values ranges of the SFR of palatal (PS) and upper labial (LS) mucosa in subjects with and without xerostomia. Methods. A cross-sectional study was conducted among subjects distributed in three groups according to their unstimulated and stimulated whole saliva. Results. 144 subjects were enrolled in groups as follows: severe hyposalivation (n = 24), mild hyposalivation (n = 78), and normosalivation (n = 42). The mean and the 95% confidence interval for the LS flow rate (μL/cm²/min) were 3.2 (2.46 to 3.94), 5.86 (4.96 to 6.75), and 9.08 (7.63 to 10.53) (P < 0.001) for each group, respectively. The PS results were 1.01 (0.68 to 1.34), 1.72 (1.31 to 2.13), and 2.44 (1.66 to 3.22) (P = 0.014). Xerostomia complainers presented lower rates of LS (5.17 (4.06 to 6.23)) than non-complainers (7.33 (6.4 to 8.27)) (P = 0.003). Conclusions. The test was reliable to provide referential values ranges for LS flow rate measurement and was shown to be valid to distinguish normosalivation from severe and mild hyposalivation and also to predict xerostomia.

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.

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.

Salivation in healthy schoolchildren

OBJECTIVE

To obtain reference data on the unstimulated salivary flow rate in healthy 6-11-year-old boys and girls, for use in the treatment of drooling in mentally and physically handicapped children.

METHODS

Under standard conditions unstimulated saliva was collected from 62 healthy children using the swab method. Flow rate was determined by calculating the increase in weight of cotton rolls placed in the mouth for 5 min. The influence of the variables age, gender and type of gland were evaluated.

RESULTS

No significant difference was found between the flow rate in boys and girls or between the children in this age window. The swab method showed good reproducibility. The right and left parotid glands had equal flow rates of 0.15 ml/min. The flow rate in the floor of the mouth secreted by the submandibular and sublingual glands was 0.32 ml/min.

CONCLUSIONS

In healthy children of 6-11 years, age and gender did not influence the salivary flow rate and therefore do not have to be taken in consideration when measuring salivary flow rate. The swab method was reliable, easy to carry out and well-tolerated by the group of schoolchildren.

Fine structure of the 7 postnatal days Calomys callosus palatine salivary glands

The aim of this study has been to determine the ultrastructural characteristics of the minor palatine salivary glands on the seventh day of development and to demonstrate wether their secretion is mucous, serous or seromucous by light, transmission and scanning electron microscopy. This study has shown that the palatine gland acinar cells are predominantly mucous with some serous units. These cells contain electron dense (serous) and low electron dense (mucous) granules in the apical portions. The cytoplasmatic organelles like mitochondria, Golgi apparatus and rough endoplasmic reticulum are localized in a supranuclear portion. We could also observe the flattened myoepithelial cells surrounding the basal part of the acini with myofilaments, Golgi apparatus and mitochondria. Desmosomal junctions and membrane interdigitations are present between the acinar and the myoepithelial cells. A basal lamina, divided in two layers, an electron dense and an electron lucent is present between the glandular stroma which is composed of dense connective tissue and the endpieces.

Analysis of residual saliva and minor salivary gland secretions

Residual saliva and minor salivary gland secretions are important for the maintenance of oral mucosal wetness. Salivary proteins and glycoproteins are the major components of the oral mucosal film, which functions as a moisture retainer and a protective barrier. Here, the correlations between the amounts of residual saliva and minor salivary gland secretions and their protein concentrations were investigated in 30 normal healthy individuals. The thickness of the mucosal film was measured at six mucosal surfaces and minor salivary gland secretion rate was measured at two mucosal surfaces. The thickness of residual saliva was determined by placing filter-paper strips against the mucosa at each site for 5 s and then measuring the volume electronically with a Periotron 8000 micro-moisture meter. The unstimulated rate of minor salivary gland secretion was measured for 30 s by the same method. Unstimulated whole salivary flow rate was measured with the spitting method. The total protein concentration of all salivary samples was measured by bicinchoninic acid assay. Before the experiment, the intra-/inter-examiner reliability of the method using the Periotron and the filter-paper strips was investigated. With a range of 0.4256-0.8846, the intraclass correlation coefficient, measured within and between examiners, was indicative of good reliability. The oral mucosal site with the thinnest coat of residual saliva was the anterior hard palate. Mucosal wetness on the hard palate and buccal mucosa showed significant positive correlations with the unstimulated whole salivary flow rate and significant negative correlations with the total protein concentration of residual saliva. Mucosal wetness on the upper and lower labial mucosa also showed significant negative correlations with the total protein concentration of residual saliva. Mucosal wetness on the soft palate was correlated with the minor salivary gland secretion rate (r=0.477, P<0.01). Among the minor salivary glands, the secretion rate of soft palate glands in females showed a significant correlation with the unstimulated whole salivary flow rate (r=0.563, P<0.05) and a significant negative correlation with its total protein concentration (r=-0.525, P<0.05). These data suggested that oral mucosal wetness and minor salivary gland secretions could be influenced by various factors differently according to mucosal sites.

Studies on human minor salivary gland secretions using the Periotron method

Secretions from minor salivary glands were estimated in 127 individuals by the Periotron method of measuring fluid output from different mucosal sites, and outputs were related to different variables. Large intra- and interindividual variations in secretions (expressed as microliter/cm2 per min) were observed, with means of 0.9 for the palatal, 4.8 for the labial and 16.0 for the buccal mucosal sites. Age had no influence on the secretion rate, but women had 10-20% lower values from all three sites than men (p < 0.05). Individuals wearing upper dentures or using tobacco had 300 and 27% increased palatal secretion rates, respectively (p < 0.001, p < 0.05). In addition, those being treated with diuretics had 15% lower rates of secretion from buccal mucosal glands (p < 0.05), and those complaining of oral dryness had 21% lower fluid output from the labial mucosa (p < 0.05). These results support the use of minor salivary glands in combination with the Periotron method to study mucosal secretions and functions.

The flow rate of unstimulated human labial gland saliva

Although the minor salivary glands contribute an important fraction of the resting flow of saliva, which may be particularly relevant in xerostomia, there is currently no precise method of measuring the flow from individual glands or recording the number of active glands in a given area. These experiments were devised to test a photographic method of assaying labial gland saliva and to see whether subjects of different ages had differing flow rates and/or numbers of glands. Unstimulated saliva secretion from labial salivary glands was measured in healthy non-medicated subjects aged 20 to 55 years by a photographic method. The number of glands in a unit area, the individual gland flow rates, and the flow rates per unit area were assessed. There was a high correlation between flow rate per unit area as measured by this method and measurements from weighing filter paper before and after absorption of the saliva droplets when the latter method could be used. The mean flow rate for 22 subjects was 2.35 +/- 1.65 microL/min over the whole area photographed. Subjects with higher flow rates had both more active glands and a higher rate of secretion from individual glands. There was no correlation between either number of active glands in a unit area or of flow rate and age in the age range represented by these subjects.

Influence of age on the secretory rates of the human minor salivary glands and whole saliva

This investigation comprised two studies of healthy, unmedicated individuals. The first measured the effect of collection time on the volume of secretions of the minor salivary glands at four specified areas of the lower lip of 13 individuals before and after a mild gustatory stimulus. The second (n = 51) monitored the influence of age and gender on the secretory rates of unstimulated labial, buccal and palatal salivary glands. Also, unstimulated and stimulated flow rates of whole saliva were monitored to provide a point of reference. Volumes of minor gland secretions were measured with a Periotron unit. Results of the first study indicated a linear increase in volumes with collection time (15, 30, 45 and 60 s). Flow rates were similar among the four labial sites, approx. 1 microliter/cm2/min, and were not influenced by mild citric acid stimulation. Results of the second study indicated that flow rates differed significantly (p = 0.0001) among the anatomical sites, with similar rates on the right- and left-hand sides. Gender exerted no influence on flow from the minor salivary glands. Similarly, age exerted no influence on flow from the buccal or labial glands. However, the secretory rate for the palatal glands decreased significantly with age (r = -0.44; p < 0.005). As for unstimulated whole saliva, secretory rates were not influenced by age nor gender; rates for stimulated whole saliva increased with age (r = 0.31; p < 0.05). No association was detected between the flow rates of the whole saliva and that of the minor salivary glands.