Measurement and comparison of the residual saliva on various oral mucosal and dentition surfaces in humans

Determinants of Microscale pH in In Situ-Grown Dental Biofilms

Dental biofilm pH is the most important determinant of virulence for the development of caries lesions. Confocal microscopy-based pH ratiometry allows monitoring biofilm pH with high spatial resolution. Experiments performed on simplified biofilm models under static conditions identified steep pH gradients as well as localized acidogenic foci that promote enamel demineralization. The present work used pH ratiometry to perform a comprehensive analysis of the effect of whole saliva flow on the microscale pH in complex, in situ-grown 48-h and 96-h biofilms (n = 54) from 9 healthy participants. pH was monitored in 12 areas at the biofilm bottom and top, and saliva flow with film thicknesses corresponding to those in the oral cavity was provided by an additively manufactured microfluidic flow cell. Biofilm pH was correlated to the bacterial composition, as determined by 16S rRNA gene sequencing. Biofilm acidogenicity varied considerably between participants and individual biofilms but also between different areas inside one biofilm, with pH gradients of up to 2 units. pH drops were more pronounced in 96-h than in 48-h biofilms (P = 0.0121) and virtually unaffected by unstimulated saliva flow (0.8 mm/min). Stimulated flow (8 mm/min) raised average biofilm pH to near-neutral values but it did not equilibrate vertical and horizontal pH gradients in the biofilms. pH was significantly lower at the biofilm base than at the top (P < 0.0001) and lower downstream than upstream (P = 0.0046), due to an accumulation of acids along the flow path. pH drops were positively correlated with biofilm thickness and negatively with the thickness of the saliva film covering the biofilm. Bacterial community composition was significantly different between biofilms with strong and weak pH responses but not their species richness. The present experimental study demonstrates that stimulated saliva flow, saliva film thickness, biofilm age, biofilm thickness, and bacterial composition are important modulators of microscale pH in dental biofilms.

Oral biosciences: The annual review 2022

BACKGROUND

The Journal of Oral Biosciences is devoted to advancing and disseminating fundamental knowledge concerning every aspect of oral biosciences.

HIGHLIGHT

This review features review articles in the fields of "Bone Cell Biology," "Tooth Development & Regeneration," "Tooth Bleaching," "Adipokines," "Milk Thistle," "Epithelial-Mesenchymal Transition," "Periodontitis," "Diagnosis," "Salivary Glands," "Tooth Root," "Exosome," "New Perspectives of Tooth Identification," "Dental Pulp," and "Saliva" in addition to the review articles by the winner of the "Lion Dental Research Award" ("Plastic changes in nociceptive pathways contributing to persistent orofacial pain") presented by the Japanese Association for Oral Biology.

CONCLUSION

The review articles in the Journal of Oral Biosciences have inspired its readers to broaden their knowledge about various aspects of oral biosciences. The current editorial review introduces these exciting review articles.

Salivary film thickness and MUC5B levels at various intra-oral surfaces

OBJECTIVES

In this study, we investigated the salivary film thickness and the MUC5B levels at various intra-oral locations in healthy volunteers, with a focus on the palate. Besides, measurements of the palatal surface area were included to explore the possible relationships between the palatal surface area and the palatal salivary film and MUC5B levels.

MATERIALS AND METHODS

The salivary film thickness was determined using filter strips, which were pressed to the mucosal surfaces of five different intra-oral locations; conductance was then analysed using a Periotron. After elution of the strips, the MUC5B levels at various intra-oral locations were determined using ELISA. The palatal surface area was measured using an intra-oral scanner. The surface area was subsequently calculated using the software.

RESULTS

The anterior tongue had the thickest salivary film and also the highest levels of MUC5B, while the anterior palate had the thinnest salivary film and lowest MUC5B levels. There was no association between the palatal surface area and the salivary film thickness of the palate.

CONCLUSION

The salivary film and MUC5B levels are unequally distributed over the intra-oral regions of the soft tissues. The lack of association between the palatal surface area and the salivary film thickness indicates that a larger surface area is not associated with a relative thinner palatal salivary film.

CLINICAL RELEVANCE

The results of the current study increase our understanding of saliva distribution in the oral cavity and could be used as reference values for future studies.

Correlations of palatal surface area with anthropometric dimensions of the head and face

Purpose

Saliva distribution over the palatal surface plays an important role in the perception of dry mouth. It is envisaged that non-invasive estimation of the palatal surface area by anthropometric measurements of the head and face can be useful in the assessment of oral dryness. For this purpose, the relationship between the palatal surface area and anthropometric measurements of the head and face was investigated.

Methods

The palatal surface was measured in 51 healthy volunteers using an intra-oral scanner. The distances between anthropometric landmarks of the head and face were determined using an anatomical sliding caliper. Correlations between the palatal surface area and the anthropometric landmarks were investigated.

Results

The median palatal surface area for the total study population was found to be 2120.6 mm². Virtually, all anthropometric measurements showed significant differences between females and males. Various head and face measurements had a significant correlation with the palatal surface area. However, these correlations disappeared when the participants were stratified based on their sex, with the exception of mandibular length and palatal width in females.

Conclusion

The surface area of the palate correlates with nearly all anthropometric measurements of the head and face included in this study. Yet, the clinical applicability seems limited to females.

Using the modified Schirmer test for dry mouth assessment: A cross-sectional study

This study aimed to establish whether the modified Schirmer test could serve as a diagnostic tool for dry mouth, that is, whether it could reliably measure salivary film at selected locations within the oral cavity, and to identify levels of sensitivity/specificity and determine reference values. Therefore, a cross-sectional study (N = 120, mean age 63.5 [SD 13.9] years) was performed. The test was used at five locations (hard palate; buccal mucosa in molar region at 4 mm above occlusal plane; anterior tongue; lower lip; mouth floor), and results were recorded after 1, 2 and 3 min. A statistically significant discriminatory ability of the Schirmer test for the unstimulated salivary flow rates could be shown for the palate (at 3 min), buccal mucosa (at 1 min), mouth floor (at 1 min), and tongue (at 2 and 3 min) (areas under the curve 0.64-0.68), with individual sensitivity/specificity values depending on test location/time points. Thus, the modified Schirmer test has potential to become a simple and reproducible instrument for the detection of dry mouth based on low unstimulated salivary flow rates in dentistry and especially outreach care. Care must be taken concerning intraoral test location and measurement time.

The association between oral dryness and use of dry-mouth interventions in Sjögren's syndrome patients

Objective

Sjögren’s syndrome patients use different dry-mouth interventions for the relieve of their oral dryness. Recently, it was shown that patients with dry-mouth complaints have regional differences in perceived intra-oral dryness. Therefore, the aim of the present study was to investigate whether the use of dry-mouth interventions is related to the perceived regional oral dryness.

Materials and methods

A cross-sectional study was performed among Sjögren’s patients. Volunteers could anonymously administer various questionnaires, including the Regional Oral Dryness Inventory (RODI), Xerostomia Inventory (XI), Bother Index (BI) and a list of dry-mouth interventions.

Results

Sjögren’s syndrome patients use a wide variety for the relieve of oral dryness. “Drinking water’’ and “moistening the lips’’ were used most frequently. Dry-mouth interventions, “drinking water’’, “rinsing of the mouth”, and “drinking small volumes” had significant associations with the RODI-scores of the posterior palate, and anterior and posterior tongue, respectively. On the other hand, “using mouth gel’’ had a significant association with the RODI-scores of the inside cheeks.

Conclusion

Sjögren’s syndrome patients are more likely to use mouth gels when their inside cheeks were experienced as most dry, while they drank water, rinsed their mouth or drank small volumes if the posterior palate, and anterior and posterior tongue were considered as dry. It can be concluded that intra-oral dryness affects dry-mouth perception and thereby also the use of the various dry-mouth interventions.

Clinical relevance

The therapeutic choice of dry-mouth interventions by Sjögren’s syndrome patients seems to some extent to be related to dryness at specific intra-oral regions.

Ratiometric imaging of extracellular pH in Streptococcus mutans biofilms exposed to different flow velocities and saliva film thicknesses

Introduction: Fluid flow has a prominent influence on the metabolism of surface-attached biofilms. Dental biofilms are covered by a thin saliva film that flows at different rates in different locations under stimulated and unstimulated conditions. Methods:The present study employed pH ratiometry to study the impact of different flow velocities, saliva film thicknesses and saliva concentrations on microscale pH developments in Streptococcus mutans biofilms of different age. Results:While saliva flow at a velocity of 0.8 mm/min (unstimulated flow) had little impact on biofilm pH, stimulated flow (8 mm/min; 80 mm/min) affected vertical pH gradients in the biofilms and raised the average pH in 48-h biofilms, but not in 72-h and 168-h biofilms. The saliva film thickness had a strong impact on biofilm pH under both static and dynamic conditions. pH drops were significantly higher in biofilms exposed to a thin saliva film (≤ 50 µm) than a thick saliva film (> 50 µm). pH drops in the biofilms were also strongly dependent on the saliva concentration and thus the buffer capacity of the salivary medium. For 48-h and 72-h biofilms, but not for 168-h biofilms, pH drops in distinct microenvironments were more pronounced when the local biofilm thickness was high.

Oral dryness and moisture degree at the lingual but not buccal mucosa predict prognosis in end-of-life cancer patients

PURPOSE

The aim of this study is to investigate the association of oral dryness with overall survival and determine the threshold points of moisture degree for predicting 7-day survival in palliative care patients.

METHODS

A total of 147 consecutive palliative care patients were included between January 2017 and November 2018. Oral dryness at the lingual and buccal mucosa was measured using an oral moisture-checking device. Overall survival was compared between patients with and without oral dryness using Kaplan-Meier curves with a log-rank test. Prediction accuracy was evaluated by the receiver operating characteristic (ROC) curve and the area under the curve (AUC).

RESULTS

Median survival (95% confidence interval) in patients with oral dryness at the lingual mucosa was shorter than that in patients without oral dryness (17 [11-24] days vs. 28 [22-37] days, log-rank test, p <0.001), but not at the buccal mucosa. Time-dependent ROC revealed that the AUCs for 7-, 14-, 21-, and 28-day survival predictions were 0.72, 0.68, 0.61, and 0.59 with a cutoff value of 19.2%, respectively. The prevalence of performance status (PS) 4 and oxygen administration in the 7-day death group were higher than those in the non-7-day death group. A stratified analysis indicated that moisture degree <19.2% showed fair predictive performance with an AUC of 0.74 and 0.74, in the case of PS ≤3 or without oxygen administration.

CONCLUSION

Oral dryness was associated with increased risk of mortality in palliative care patients. Moisture degree <19.2% at the lingual mucosa predicted less than 7-day survival.

Differences in perceived intra-oral dryness in various dry-mouth patients as determined using the Regional Oral Dryness Inventory

Objectives

Recently, it was shown that the Regional Oral Dryness Inventory (RODI) could determine differences in dry-mouth perception at different intra-oral locations. The main aim of this study was to determine whether the RODI might help to discriminate between various causes of oral dryness in dry-mouth patients. The second aim was to ascertain whether the RODI could become an additional diagnostic tool in dry-mouth patients.

Materials and methods

Data were collected retrospectively from patients who visited a specialized saliva clinic. Salivary flow rates, Xerostomia Inventory scores, and RODI scores were extracted from the medical records. Patients were stratified into subgroups according to their health status.

Results

Five hundred twenty-eight patients participated in this study (mean age of 59.6 ± 16.0 years; 68.4% female). Specific patient groups differed with regard to the region of the mouth they experienced as the most and least dry. The posterior palate was the area perceived as most dry by controls and Sjögren patients. In patients using limited or multiple medications, it was the anterior tongue. RODI scores also differed significantly among dry-mouth patient groups: whereas controls and patients using limited medication had the lowest RODI scores and experienced less intra-oral dryness, Sjögren patients had the highest RODI scores.

Conclusion

Our use of the RODI questionnaire showed that perceived intra-oral dryness differed between the various dry-mouth patients.

Clinical relevance

The RODI can be a valuable clinical diagnostic tool in dry-mouth diagnostics, in which it can be used to discriminate between the various causes of oral dryness in patients.

Regional differences in perceived oral dryness as determined with a newly developed questionnaire, the Regional Oral Dryness Inventory

OBJECTIVES

Several questionnaires, such as the internationally validated and frequently used Xerostomia Inventory (XI), have been developed to quantify the subjective feeling of a dry mouth. These questionnaires quantify the overall perception of dry mouth but lack the possibility to differentiate between various intra-oral regions. In this light, a novel questionnaire, the Regional Oral Dryness Inventory (RODI), which quantifies the severity of dryness at various locations in the mouth, was evaluated.

MATERIALS AND METHODS

A retrospective case report study was designed. Data were collected from patients who visited the saliva clinic for Special Care Dentistry in Amsterdam. Data, including the saliva secretion rates, RODI scores, the Xerostomia Inventory (XI) score, and Clinical Oral Dryness Score (CODS), were extracted from the electronic health record system Oase Dental.

RESULTS

A total of 337 patients participated in this study with an average age of 54 ± 17 years. The majority of the patients were female (68.5%). The perceived dryness as determined by the RODI was the highest for the posterior palate and the lowest for the floor of the mouth. The highest correlations were found between the corresponding regions in the RODI and regionally related individual items of the XI and CODS.

CONCLUSION

There is a significant difference in dry-mouth feeling at different intra-oral locations.

CLINICAL RELEVANCE

Regional evaluation of xerostomia with RODI might improve diagnosis of xerostomia by helping to discriminate between different potential causes of oral dryness in patients and for evaluating the efficacy of mouth-moistening products. RODI is highly accessible and easy to perform in dental practices during routine clinical assessment.

Influence of saliva on the results of global laboratory coagulation tests

BACKGROUND

Oral wounds inevitably come into contact with saliva which can affect the time needed for bleeding to stop. The influence of saliva can be non-specific, related to dilution of blood, and/or mediated by salivary factors that affect haemostasis directly. The aim of this study was to assess if mixing blood with an individual's saliva would affect the rate of its coagulation measured by global coagulation tests, prothrombin time (PT) and activated partial thromboplastin time (APTT).

METHODS

The study included 30 healthy non-smoking volunteers. Paired blood and unstimulated saliva samples were obtained from each participant and PT and APTT were determined in blood, blood + saliva and blood + water mixtures. Coagulation tests were performed using the mechanical clot detection method.

RESULTS

PT was significantly longer in both blood + saliva and blood + water mixtures compared to blood alone. APTT was significantly longer only in blood + water mixture compared to blood.

CONCLUSIONS

Similarly prolonged PT in both mixtures suggests that both saliva and water prolong coagulation evenly due to their non-specific effect of blood dilution. The finding that APTT was significantly prolonged only when blood was mixed with water could indicate presence of tissue factor in saliva, however, in a concentration too low to influence the results of PT.

Influence of mouth breathing on outcome of scaling and root planing in chronic periodontitis

Introduction

Dryness is known to be associated with inflammatory diseases such as dry eye disease and atopic dermatitis. There is significant water loss from the oral cavity during mouth breathing. This study is conducted to estimate the influence of mouth breathing on the outcome of scaling and root planing (SRP) in chronic periodontitis (CP).

Materials and methods

CP patients comprising of 33 mouth breathers (MBs) and 33 nose breathers (NBs) were recruited. Thirty patients in each group completed the study. At baseline, plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), and clinical attachment level (CAL) were measured. SRP was done in both groups. At the 4th, 8th, and 12th week, PI, GI, and BOP were recorded. PD and CAL were also assessed at the 12th week.

Results

At the 12th week, there was significantly less improvement in GI at palatal sites of maxillary anterior and maxillary posterior teeth in MB group. Sixty-nine percent of BOP positive sites with PD >4 mm were converted into BOP negative sites with PD ≤4 mm in maxillary posterior palatal sites in NB. This success was 38% in MB.

Conclusion

Control of periodontal inflammation by SRP in CP patients is affected at palatal sites of mouth breathers.

Salivary functions in mastication, taste and textural perception, swallowing and initial digestion

Saliva exerts multiple functions in relation to the initial digestive processes taking place in the upper parts of the gastrointestinal tract. Ingestion of food and beverages, in turn, is a strong stimulus for secretion of saliva with a differential composition depending on the neuronal stimulation pattern. This review paper provides insight into the mechanisms by which saliva acts in relation to taste, mastication, bolus formation, enzymatic digestion and swallowing. Also, the protective functions of saliva including maintenance of dental and mucosal integrity will be discussed as they indirectly influence the digestive process. The final part of this study focuses on the implications of xerostomia and salivary gland dysfunction on gastrointestinal functions.

Frogs use a viscoelastic tongue and non-Newtonian saliva to catch prey

Frogs can capture insects, mice and even birds using only their tongue, with a speed and versatility unmatched in the world of synthetic materials. How can the frog tongue be so sticky? In this combined experimental and theoretical study, we perform a series of high-speed films, material tests on the tongue, and rheological tests of the frog saliva. We show that the tongue's unique stickiness results from a combination of a soft, viscoelastic tongue coupled with non-Newtonian saliva. The tongue acts like a car's shock absorber during insect capture, absorbing energy and so preventing separation from the insect. The shear-thinning saliva spreads over the insect during impact, grips it firmly during tongue retraction, and slides off during swallowing. This combination of properties gives the tongue 50 times greater work of adhesion than known synthetic polymer materials such as the sticky-hand toy. These principles may inspire the design of reversible adhesives for high-speed application.

A randomized, double-blind, placebo-controlled trial of a traditional herbal formula, Yukmijihwang-tang in elderly subjects with xerostomia

ETHNOPHARMACOLOGICAL RELEVANCE

Yukmijihwang-tang (YMJ) is a typical herbal formula to treat Yin-deficiency (YD) syndrome by enriching the fluid-humor of the body. YMJ has been used to treat dry mouth symptoms for hundreds of years in traditional East Asian medicine. Xerostomia, a subjective oral dryness, is common in the elderly and results in impaired quality of life. Many conventional treatments for xerostomia provide only temporary symptom relief, and have side effects. The aim of this study is to investigate the efficacy and safety of YMJ for the treatment of xerostomia in the elderly.

METHODS

This study was designed as a randomized, placebo-controlled, double-blinded, two center trial. Ninety-six subjects aged 60-80 years who had experienced xerostomia for at least 3 months and presented with score>40 on the visual analog scale (VAS) for subjective oral dryness were recruited and randomly allocated to YMJ and placebo groups. YMJ or placebo was administered to each group for 8 weeks (3g of YMJ or placebo, three times per day). The primary outcome was change of VAS for xerostomia from 0 to 8 weeks.

RESULTS

VAS for xerostomia was decreased by 22.04±22.76 in the YMJ group and 23.58±23.04 in the placebo group. YMJ had no effect on xerostomia. However, participants with BMIs lower than 29.37kg/m(2) showed improvement of xerostomia after 8 weeks of treatment with YMJ compared to placebo. In addition, YMJ improved oral moisture, which is associated with subjective oral dryness in the YMJ group, and the relationship between VAS for xerostomia and YD was significant.

CONCLUSION

A trend was observed in which YMJ improved oral moisture status and subjective oral dryness in elderly subjects with lower BMI and greater tendency toward YD.

Salivary gland dysfunction and xerostomia in Sjögren's syndrome

In this article, salivary gland dysfunction and xerostomia in Sjögren's syndrome (SS) are discussed, with a focus on the pathophysiology of salivary dysfunction in SS, the clinical presentation of dry mouth in SS, how to assess salivary gland hypofunction and xerostomia in SS, and the impact of salivary gland dysfunction on quality of life in patients with SS.

Anti-caries effect of CPP-ACP in irradiated nasopharyngeal carcinoma patients

OBJECTIVE

The aim of this study was to determine the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on caries progression in irradiated nasopharyngeal carcinoma (NPC) patients.

METHODS

Twenty-one males and three females (median age, 50 years) were randomized into two groups before radiotherapy. Subjects had at least eight teeth after oral health clearance. The test group used 0.4 % stannous fluoride gel and a crème containing 10 % CPP-ACP daily; the control group used a similar crème without CPP-ACP and otherwise identical care. Subjects applied the crème three times daily and fluoride gel once daily. Caries status, saliva and plaque parameters were measured pre-radiotherapy, at 2 weeks and 3 months post-radiotherapy.

RESULTS

Baseline International Caries Detection and Assessment System (ICDAS) scores were 0-1126 surfaces (93.9 %), 1-28 surfaces (2.3 %), 2-40 surfaces (3.3 %) and 3-6 surfaces (0.5 %) for the control and 0-1186 surfaces (95.6 %), 1-31 surfaces (2.5 %), 2-15 surfaces (1.2 %) and 3-8 surfaces (0.7 %) for the test group. Twenty-two subjects returned at 3 months post-radiotherapy with reduced plaque pH, salivary flow, pH and buffering capacity. Nine test and 8 control subjects developed 32 and 59 new caries lesions, respectively. Test subjects showed lower caries progression than the controls: all surfaces (OR 0.51, 95 % CI 0.17∼1.59), occlusal (OR 0.20, 95 % CI 0.03∼1.29) and smooth surfaces (OR 0.61, 95 % CI 0.16∼2.38). The difference was not statistically significant.

CONCLUSION

Application of CPP-ACP did not significantly reduce caries progression in NPC patients in the first 3 months after radiotherapy as compared to controls.

CLINICAL RELEVANCE

Adjunct use of CPP-ACP with stannous fluoride gel in irradiated NPC patients gave comparable results compared to stannous fluoride gel alone in reducing caries progression.

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.

Comparative analysis of gingival wetness at natural teeth and dental implant sites

BACKGROUND

"Gingival Wetness (GW)," which is the thickness of residual saliva on gingiva, functions as a moisture retainer and a protective barrier for microbial colonization. Whether dental implant (DI) treatment affects GW scores and whether gingival inflammation has the capacity to alter GW remains unknown. Thus, this study was designed to evaluate the potential impact of DI treatment on GW.

METHODS

A total of 118 DIs and natural teeth (NT) sites were comparatively analyzed. Clinical periodontal and periimplant status were determined. Sites were classified into 2 subgroups based on the clinical inflammatory status as inflamed or noninflamed. GW was measured by standardized paper strips and quantified by micromoisture meter.

RESULTS

Gingival index, clinical attachment loss, plaque index, and gingival bleeding time index scores were generally lower at DI sites. Significant differences were seen in clinical attachment loss, plaque index, and gingival bleeding time index in inflamed sites, presenting higher scores for NT. Comparable values were observed for DI and NT regarding GW for all sites. No differences were noticed in GW scores between the noninflamed NT and DI sites and also wheninflamed sites were concerned.

CONCLUSIONS

DI treatment does not seem to result in any apparent reduction in GW. Thus, it can be speculated that similar protective processes may occur at dental implant and NT sites. Furthermore, GW does not seem to depend on the local inflammatory status of the soft tissues.

Associations between oral and ocular dryness, labial and whole salivary flow rates, systemic diseases and medications in a sample of older people

OBJECTIVE

To investigate the associations between age, gender, systemic diseases, medications, labial and whole salivary flow rates and oral and ocular dryness in older people.

METHODS

Symptoms of oral and ocular dryness, systemic diseases, medications (coded according to the Anatomical therapeutic chemical (ATC) classification system), tobacco and alcohol consumption were registered, and unstimulated labial (LS) and unstimulated (UWS) and chewing-stimulated (SWS) whole salivary flow rates were measured in 668 randomly selected community-dwelling elderly aged 65-95.

RESULTS

Presence of oral (12%) and ocular (11%) dryness was positively correlated. Oral dryness was associated with low UWS, SWS and LS, and ocular dryness with low UWS and SWS. Oral and ocular dryness was related to female gender, but not to age. Only four persons in the healthy and nonmedicated subgroups reported oral and ocular dryness. The numbers of diseases and medications were higher in the older age groups and associated with oral and ocular dryness, low UWS, SWS and LS. On average, women were slightly older, reported more oral and ocular dryness and had lower UWS, SWS, LS and higher numbers of diseases and medications. High prevalence and odds ratios for oral dryness were associated with metabolic, respiratory and neurological diseases and intake of thyroid hormones, respiratory agents (primarily glucocorticoids), psycholeptics and/or psychoanaleptics, antineoplastics, proton pump inhibitors, antidiabetics, loop diuretics, antispasmodics, quinine and bisphosphonates. Ocular dryness was especially associated with neurological diseases and intake of psycholeptics and/or psychoanaleptics. Intake of magnesium hydroxide, antithrombotics, cardiac agents, thiazides, beta-blockers, calcium channel blockers, ACE inhibitors/angiotensin II antagonists, statins, glucosamine, paracetamol/opioids, ophthalmologicals and certain combination therapies was related to oral and ocular dryness.

CONCLUSIONS

In older people, oral and ocular dryness are associated with low salivary flow rates, specific as well as high number of diseases and medications, but neither with age and gender per se nor with tobacco and alcohol consumption. New detailed information concerning associations between medications and oral and ocular dryness has been obtained using the ATC classification system.

Investigating the relationship between hyposalivation and mucosal wetness

BACKGROUND

Mucosal wetness (MW) reflects the layer of residual saliva that covers the oral mucosal surfaces.

OBJECTIVES

The aim of this study was to determine MW at different oral mucosa sites and to investigate the relationship between MW, unstimulated whole salivary flow rates (UWS) and Clinical Oral Dryness Score (CODS).

METHOD

A total of 100 dry mouth patients and 50 healthy subjects participated in the study. MW was sampled with filter paper strips at four sites inside the mouth; anterior hard palate (AHP), buccal mucosa (BUC), anterior tongue (AT), lower lip (LL) and measured with a micro-moisture meter. Reproducibility was assessed by repeated sampling and diurnal variation was examined.

RESULTS

Mucosal wetness in healthy subjects differed according to site and means±SD were; AHP (11± 11.7μm), BUC (32±14.8μm), AT (65±17.2μm), and LL (25 ±13.5μm). Dry mouth patients with reduced UWS showed increased CODS. MW at all four sites was significantly reduced (P<0.05) in dry mouth patients compared with the healthy subjects. Reproducibility of MW measurement using the intra-class correlation coefficient showed agreement at different visits within subject. MW of the AT showed a positive correlation with UWS (P<0.05).

CONCLUSION

Mucosal wetness is a reliable measure of oral dryness and had a positive correlation with UWS.

Salivary flow rate, calcium, urea, total protein, and amylase levels in fanconi anemia

OBJECTIVES

Fanconi anemia (FA) is a genetic disease characterized by a chromosomal instability that develops a progressive pancitopenia, leukemia, and/or solid tumors. Nevertheless, it is unknown if this illness induces changes on the salivary gland parenchyma and function. The aim of this study was to assess the stimulated salivary flow rate (SSFR) and calcium, urea, total protein, and amylase levels in saliva of FA patients.

METHODS

Stimulated whole saliva was collected from 34 randomly selected FA patients and 34 age-matched and sex-matched controls. Both samples were analyzed for salivary flow rate, calcium, urea, total proteins, and amylase. The SSFR was analyzed by gravimetric method and calcium, urea, total protein, and amylase concentrations were realized by chemistry tests.

RESULTS

Mean values of SSFR for experimental and control groups were, respectively, 0.5 mL/min and 0.8 mL/min (P<0.05). Calcium concentration was 36% (P<0.05) and urea concentration was 21% (P<0.01) lower in the FA group saliva compared with saliva from the controls. The saliva concentration of amylase was almost equal in both groups.

CONCLUSIONS

FA patients may exhibit significant changes in SSFR, calcium, and urea concentration of saliva.

Comparison of the composition of oral mucosal residual saliva with whole saliva

OBJECTIVE

Compared with whole saliva, residual saliva comprising the oral mucosal film shows a high protein concentration. The purpose of this study was to compare the composition of residual saliva with unstimulated and stimulated whole saliva in normosalivators.

MATERIALS AND METHODS

The composition of oral mucosal residual saliva in 30 healthy individuals was investigated and compared with that of whole saliva. The concentrations of total protein, secretory immunoglobin A (sIgA), lactoferrin, total carbohydrate, and sialic acid were examined. The activities of peroxidase, lysozyme and alpha-amylase were determined.

RESULTS

Residual saliva had higher levels of total protein and carbohydrate than whole saliva, with a higher carbohydrate to protein ratio in the residual saliva suggesting that salivary glycoproteins are concentrated on the oral mucosal surface. sIgA, lactoferrin and sialic acid were present as highly concentrated forms in residual saliva. The enzymatic activity of peroxidase in residual saliva was higher than that of whole saliva.

CONCLUSIONS

These concentrated carbohydrate and antimicrobials on the oral mucosal surface work for mucosal defence and could be used for targeting sites for the delivery of therapeutic agents.

Signs of oral dryness in relation to salivary flow rate, pH, buffering capacity and dry mouth complaints

Background

This study aimed to investigate the signs of oral dryness in relation to different salivary variables and to correlate subjective complaints of oral dryness with salivary flow rate.

Methods

312 unmedicated healthy individuals belonging to three age groups, (6–11, 12–17, and 18–40 years) were examined clinically for signs of oral dryness. Resting and stimulated saliva were collected to determine flow rate, pH and buffering capacity. A questionnaire was used to obtain information on subjective sensation of dry mouth.

Results

Dry lip and dry mucosa were present in 37.5% and 3.2% of the sample respectively. The proportion of subjects who complained of oral dryness (19%) showed a stimulated salivary flow rate significantly lower than non complainers. Dry lip was significantly related to low resting flow rate but pH and buffering capacity did not show any significant relation to dry lip. Dry mucosa was not related to any of the above mentioned parameters.

Conclusion

The finding that the stimulated salivary flow rate was reduced in subjects complaining of dry mouth is of great clinical relevance, since the reduction is expected to be reflected in compromising various salivary functions.

The distribution of oral mucosal pH values in healthy saliva secretors

OBJECTIVES

To establish the normal range of oral mucosal pH and to correlate these measurements to salivary flow rate in healthy individuals according to age and gender.

SUBJECTS AND METHODS

Measurements of pH levels using a flat pH meter and salivary secretion rates were established in eight mucosal sites from a total of 50 healthy individuals.

RESULTS

The mean pH (+/-s.d.) of all sites was 6.78 +/- 0.04 with significant differences between mean pH values in the palate (7.34 +/- 0.38), the floor of the mouth (6.5 +/- 0.3), the buccal mucosa (6.28 +/- 0.36) and the tongue (6.8 +/- 0.26). A significant correlation was found between age and pH at palatal and tongue sites but no gender effects were noted.

CONCLUSIONS

This method is easy and relatively quick to manipulate, and may offer many diagnostic possibilities for oral related diseases and disorders such as oral malodour, mouth breathing, dysgeusia, acidic diet consumption and gastrointestinal disorders affecting the mouth.

Application of the ‘pull-off’ force method for measurement of surface tension of upper airway mucosal lining liquid

Upper airway luminal patency is influenced by a number of factors including: intraluminal air pressure, upper airway dilator muscle activity, surrounding extraluminal tissue pressure and surface tension acting within the liquid layer lining the upper airway. In this study we examine the performance characteristics for the 'pull-off' force method for measuring the surface tension (gamma) of liquids. This method is then used to examine the gamma of the liquid lining the oro-pharynx in awake human subjects. The gamma of UAL samples (approximately 0.2 microL) obtained from the posterior pharyngeal wall was quantified using the pull-off force technique in which gamma is measured as the force required to separate two curved silica discs bridged by the liquid sample. Pull-off force measurement was not influenced by sample volumes or under different temperature or humidity conditions. The coefficients of variation for repeated measurements using the pull-off force technique for the three standard liquids ranged from 1.2% to 5.6%. The pull-off method tended to give slightly lower values than the Wihelmy balance method with the mean difference being 2.4 +/- 1.8 mN m(-1). For the group, the gamma of saliva was 59.2 +/- 0.6 mN m(-1) (CV 4.9 +/- 0.9%) for five measurements of a single sample. There was no significant relationship between the measured gamma values for five subjects measured on five separate days and the day of collection of the sample for any of the subjects or the group as a whole (both p > 0.6). There was no significant difference (p = 0.53, ANOVA) between the gamma values for samples obtained from under the tongue (61.6 +/- 1.7 mN m(-1)), at the oral surface of the soft palate (56.1 +/- 3.2 mN m(-1)) and from the posterior oro-pharyngeal wall (58.1 +/- 2.4 mN m(-1)). The pull-off force method provides adequate reproducibility to be able to measure the gamma of UAL. In healthy humans the gamma of UAL is similar to that of saliva.

Usefulness of new wetness tester for diagnosis of dry mouth in disabled patients

OBJECTIVES

The condition of dry mouth is an influential factor in the incidence of caries, periodontal disease, fungal infections, masticatory dysfunctions and denture function. Bedridden elderly and disabled persons often suffer from oral dryness and the aim of this study was to evaluate the usefulness of measuring the amount of moisture in the oral mucosa for clinical diagnosis of dry mouth in this group.

SUBJECTS AND METHODS

The subjects were 20 elderly bedridden individuals, age range 65-89 years old, living in a nursing home and six healthy laboratory researchers, aged 20-46 years old, used as controls. Tongue dorsum moisture measurements were performed using a newly developed wetness tester (L-SALIVO), in which the wet portion was measured after 10 s. Further, clinical diagnosis of dry mouth was carried out using a clinical classification scale of the tongue mucosa (grade range, 0-3).

RESULTS

It was possible to measure tongue dorsum moisture in all subjects with the wetness tester. The average moisture value was 0.1+/-0.2 mm in elderly subjects with a dry mouth grade of 2 (n = 8) or 3 (n = 12), while the average moisture value in the control subjects was 3.67+/-1.75 mm with a dry mouth grade of 0 (n = 4) or 1 (n = 2). Tester values and cliniical classification showed a positive co-relationship (r = 0.31, p < 0.05).

CONCLUSIONS

Our results show that this new tester could be useful for evaluating oral dryness and diagnosing dry mouth.

Analysis of residual saliva and minor salivary gland secretions in patients with dry mouth

The importance of oral mucosal wetness in the condition of dry mouth and the role of salivary proteins in proper oral function are acknowledged. A negative correlation between mucosal wetness and the protein concentration of residual saliva has been reported in normosalivators. Here, to examine the suggestion that a reduction in residual salivary volume leads to a concomitant elevation of its protein concentration, the amount of residual saliva and minor salivary gland secretions, and their protein concentrations, were measured in hyposalivators and normosalivator controls. A Periotron 8000 micro-moisture meter was used to measure the thickness of the mucosal film at six selected mucosal surfaces and the minor salivary gland secretion rate at two mucosal surfaces. The unstimulated whole salivary flow rate was measured by the spitting method. The total protein concentration of all salivary samples was measured by bicinchoninic acid assay. The hyposalivators had significantly lower amounts of residual saliva and minor salivary gland secretions than the normosalivators at all selected mucosal sites except the soft palate. In both groups, the site with the thinnest coat of residual saliva was the anterior hard palate and the wettest site was the anterior dorsal mucosa of the tongue. The protein concentration of residual saliva was significantly higher in hyposalivators than normosalivators. In the minor salivary gland secretions there was no significant difference in protein concentration between the normo- and hyposalivators. When the hyposalivators were divided into two subgroups according to their severity of dryness, the reduction of residual salivary volume and the elevation of protein concentration were more apparent in the group with the more severe dry mouth. Collectively, these results indicate that oral mucosal wetness is associated with the flow rate of unstimulated whole saliva. The function of the minor salivary glands was less affected and relatively well preserved in patients with dry mouth. The increased protein concentration of residual saliva in the hyposalivators appeared to be the result of decreased salivary volume.

Role of saliva in oral dryness, oral feel and oral malodour

Patients who believe they have oral malodour often have a dry mouth condition instead. Here we have examined its relation to oral malodour, real or perceived. A direct relationship between the thickness of the film of residual saliva on mucosal surfaces throughout the mouth and perception of a dry mouth was observed. On the hard palate, the thickness of this film proved to be diagnostic for a dry mouth and corresponded to lower resting saliva flow and pH levels (P< 0.001). Intra-muscular administration of the anti-sialogogue, Robinul, accurately produced the dry mouth condition. Using a sulphide monitor, loss of volatile sulphur compounds into mouth air progressively occurred as the mouth became drier. Mouth pH and Eh on the dorsum of the tongue correspondingly fell. Mouth breathing led to tongue and palate moisture loss thus enabling escape of malodour volatiles into mouth air. Measurement of oral dryness should make it possible to differentiate genuine malodour from dry mouth related pseudo-malodour subjects, and in turn, the latter from patients that are halitophobic. This should facilitate identification of such patients and avoid error in their clinical management.

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.

Saliva and dental plaque

Dental plaque is being redefined as oral biofilm. Diverse overlapping microbial consortia are present on all oral tissues. Biofilms are structured, displaying features like channels and projections. Constituent species switch back and forth between sessile and planktonic phases. Saliva is the medium for planktonic suspension. Several major functions can be defined for saliva in relation to oral biofilm. It serves as a medium for transporting planktonic bacteria within and between mouths. Bacteria in transit may be vulnerable to negative selection. Salivary agglutinins may prevent reattachment to surfaces. Killing by antimicrobial proteins may lead to attachment of dead cells. Salivary proteins form conditioning films on all oral surfaces. This contributes to positive selection for microbial adherence. Saliva carries chemical messengers which allow live adherent cells to sense a critical density of conspecifics. Growth begins, and thick biofilms may become resistant to antimicrobial substances. Salivary macromolecules may be catabolized, but salivary flow also may clear dietary substrates. Salivary proteins act in ways that benefit both host and microbe. All have multiple functions, and many do the same job. They form heterotypic complexes, which may exist in large micelle-like structures. These issues make it useful to compare subjects whose saliva functions differently. We have developed a simultaneous assay for aggregation, killing, live adherence, and dead adherence of oral species. Screening of 149 subjects has defined high killing/low adherence, low killing/high adherence, high killing/high adherence, and low killing/low adherence groups. These will be evaluated for differences in their flora.

Saliva in health and disease: an appraisal and update

Saliva plays an important role in oral health monitoring, regulating and maintaining the integrity of the oral hard tissues and some soft tissues. This paper reviews the role of saliva, the prevalence of oral dryness and the consequent importance of salivary flow as well as the relationship between xerostomia and salivary gland hypofunction amongst the causes of oral dryness. Other aspects of oral conditions associated with saliva are also reviewed including Sjögren's Syndrome and oesophageal function. Finally, knowledge, and the current use of salivary tests and the utilisation of saliva as a diagnostic fluid are surveyed.

The effect of ammonium glycopyrrolate (Robinul)-induced xerostomia on oral mucosal wetness and flow of gingival crevicular fluid in humans

The antisialogogue, ammonium glycopyrrolate (Robinul), was used to reduce the salivary flow rate in healthy individuals with normal salivary function to determine whether the dry-mouth symptoms and reduced amounts and patterns of oral mucosal wetness found previously in hyposalivators could be induced by this means. After baseline measurements, the drug was given to 10 healthy volunteers and their resting whole-saliva flow rate was measured at 0, 15, 60, 105 and 150 min thereafter. At the same times, the thickness of the layer of residual mucosal saliva (a measure of residual mucosal wetness) at each of 22 intraoral sites was also determined. The saliva flow rate fell from a mean of 0.45 +/- 0.07 ml/min to a mean of 0.05 +/- 0.02 ml/mm by 1 h and slowly thereafter to a mean of 0.02 +/- 0.01 to 0.03 +/- 0.01 ml/min for the remainder of the experiment. Onset of dryness symptoms was observed approx. 30 min after giving the drug. Simultaneously, the residual saliva at each of the 22 sites teted decreased to a thickness level previously found in patients with hyposalivation and who exhibited an intense feeling of dry mouth. Despite these decreases in thickness, the pattern of residual mucosal wetness throughout the mouth remained more or less unchanged. As in earlier studies, wetness was least on the hard palate and highest on the posterior dorsum of the tongue. An altered taste of the residual saliva in the mouth and an increased feeling of roughness as the tongue was passed over labial and buccal mucosal surfaces were noted. The amount of gingival crevicular fluid (GCF) in 12 gingival sites in each of the participants was also measured. Unlike the reduction in salivary flow, changes in GCF over the 150 min of the study were negligible. From this it was concluded that GCF could contribute much more to the oral fluids in dry-mouth than in normal individuals, especially when there is greater gingival inflammation.

Oral mucosal wetness in hypo- and normosalivators

After a person swallows, a film of residual saliva covers the oral hard- and soft-tissue surfaces. Here, the thickness of this film was measured at 11 selected mucosal surfaces on each side of the mouth (22 sites total) in two groups of dry-mouth and one group of normal individuals. Each group contained 25 individuals; one of the dry-mouth groups had resting flow rates < or = 0.1 ml/min while the other and the normal had flow rates above that. Residual saliva thickness was determined by placing frying-pan-shaped filter-paper strips (Sialopaper) against the mucosa at each site for 5 s and measuring the saliva volume collected with a modified Periotron 6000 micro-moisture meter; the thickness was then calculated by dividing the collected saliva volume by the strip area. The two groups with dry-mouth symptoms had mean resting (unstimulated) saliva flow rates of 0.04 and 0.19 ml/min and mean mucosal saliva thicknesses of 22.4 and 27.8 microns, respectively. The control group had a higher mean saliva flow rate of 0.39 ml/min and mucosal saliva thickness of 41.8 microns. As was observed in a previous study on normosalivators, the various sites had a characteristic pattern of wetness, with the hard palate and lips the least moist regions. In this study, these observations, were also true in the two dry-mouth groups. Lower resting saliva flow rates were associated with lower mucosal thickness of saliva and with dryness symptoms becoming evident when hyposalivation was below about 0.1-0.2 ml/min. The characteristic pattern of mucosal wetness was not affected by saliva flow rate. As saliva readily collects in the floor of the mouth and is then spread over other mucosal surfaces upon swallowing, it was suggested that hyposalivation could also lead to the dryness symptoms because there was not enough saliva to cover the various oral surfaces, especially the palate and the lips. In this regard, a critical level of moisture was proposed as necessary to protect vulnerable mucosal surfaces from becoming dry. Lower resting saliva flow rates and correspondingly lower mucosal wetness were also associated with a more acidic salivary pH, which was shown earlier to be associated with lower dental plaque pH.

Use of a paper-strip absorption method to measure the depth and volume of saliva retained in embrasures and occlusal fussae of the human dentition

Embrasures and occlusal fossae are regions of the human dentition that readily retain saliva, as well as dental plaque and dietary substrates. In this study, a wax filling and weighing technique was used to determine the volumes of these irregularly shaped spaces, and a paper-strip absorption method was developed for measuring the thickness and amounts of saliva therein. The volumes were measured on dental stone models prepared from alginate impressions of the maxillary arches of each of eight individuals and on an acrylic maxillary denture representative of the shape and alignment of normal-sized adult teeth. Embrasure volumes in the two cases were similar and ranged between 4.0 and 16.4 microliters for the individual participants, and between 4.8 and 14.9 microliters for the denture. Occlusal fossae volumes of posterior teeth determined on the denture ranged between 6.0 and 9.8 microliters. The paper-strip absorption method for the thickness or amount of saliva in embrasures or fossae consisted of the absorption of the saliva in these sites on to filter-paper strips and the measurement of the collected volumes electronically with a Periotron 6000 micro-moisture meter. Residual saliva for the embrasures between the two central incisors and the second premolar and first molar ranged between 0.12 and 0.56 with means of 0.28 and 0.37 microliter, respectively, for the same eight participants. Corresponding saliva Vmax volumes were 0.48 and 0.63 microliter, respectively. Further paper strip absorption measurements of saliva in embrasures and fossae showed a linear relation between Periopaper dipstick values and embrasure saliva volumes when these were less than 1 microliter. This range includes most residual saliva volumes normally found in these sites in vivo. For volumes of saliva greater than 1 microliter, small increments in dipstick values in embrasures corresponded to very large changes in total embrasure volumes, which reflects their exponential widening beyond about that point. For saliva thickness measurements, a blue food dye was used to construct a standard curve relating depth of saliva in embrasures and fossae (measured with an electronic micrometer) to Periopaper dipstick scores (measured with the Periotron). The relation was linear for both sites, with r values of 0.98 and 0.99, respectively (p < 0.001 for each), and was used to convert extensive in vivo depth measurements of embrasures and fossae determined in microlitres by the dipstick method in an earlier study to thicknesses in millimetres here. In the earlier study, residual saliva on oral mucosal and smooth dentition surfaces was quantified by the blotting method. Together with the method developed here, it should now be possible to measure the saliva, residual or otherwise, on all oral surfaces whether uniform or irregular in shape.