Effects of environmental temperature on saliva flow rate and secretion of protein, amylase and mucin 5B

Nitrate ingestion blunts the increase in blood pressure during cool air exposure: a double-blind, placebo-controlled, randomized, crossover trial

Cold exposure increases blood pressure (BP) and salivary flow rate (SFR). Increased cold-induced SFR would be hypothesized to enhance oral nitrate delivery for reduction to nitrite by oral anaerobes and to subsequently elevate plasma [nitrite] and nitric oxide bioavailability. We tested the hypothesis that dietary nitrate supplementation would increase plasma [nitrite] and lower BP to a greater extent in cool compared with normothermic conditions. Twelve males attended the laboratory on four occasions. Baseline measurements were completed at 28°C. Subsequently, participants ingested 140 mL of concentrated nitrate-rich (BR; ∼13 mmol nitrate) or nitrate-depleted (PL) beetroot juice. Measurements were repeated over 3 h at either 28°C (Norm) or 20°C (Cool). Mean skin temperature was lowered compared with baseline in PL-Cool and BR-Cool. SFR was greater in BR-Norm, PL-Cool, and BR-Cool than PL-Norm. Plasma [nitrite] at 3 h was higher in BR-Cool (592 ± 239 nM) versus BR-Norm (410 ± 195 nM). Systolic BP (SBP) at 3 h was not different between PL-Norm (117 ± 6 mmHg) and BR-Norm (113 ± 9 mmHg). SBP increased above baseline at 1, 2, and 3 h in PL-Cool but not BR-Cool. These results suggest that BR consumption is more effective at increasing plasma [nitrite] in cool compared with normothermic conditions and blunts the rise in BP following acute cool air exposure, which might have implications for attenuating the increased cardiovascular strain in the cold.NEW & NOTEWORTHY Compared with normothermic conditions, acute nitrate ingestion increased plasma [nitrite], a substrate for oxygen-independent nitric oxide generation, to a greater extent during cool air exposure. Systolic blood pressure was increased during cool air exposure in the placebo condition with this cool-induced blood pressure increase attenuated after acute nitrate ingestion. These findings improve our understanding of environmental factors that influence nitrate metabolism and the efficacy of nitrate supplementation to lower blood pressure.

Distinguishable short-term effects of tea and water drinking on human saliva redox

Food consumption can alter the biochemistry and redox status of human saliva, and the serving temperature of food may also play a role. The study aimed to explore the immediate (3 min) and delayed (30 min) effects of hot tea (57 ± 0.5 °C) ingestion and cold tea (8 ± 0.5 °C) ingestion on the salivary flow rate and salivary redox-relevant attributes. The saliva was collected from 20 healthy adults before, 3-min after and 30-min after the tea ingestion. The hot or cold deionised water at the same temperatures were used as control. The salivary flow rate and redox markers in hot tea (HBT), cold tea (CBT), hot water (HW) and cold water (CW) group were analysed and compared. The results demonstrated that neither the black tea nor the water altered the salivary flow rate; the black tea immediately increased the salivary thiol (SH) and malondialdehyde (MDA) content while reduced salivary uric acid (UA) significantly. The tea ingestion showed a tendency to elevate the ferric reducing antioxidant power (FRAP) in saliva, although not significantly. The water ingestion decreased the MDA content immediately and increased the UA level significantly. Cold water was found to induce a greater delayed increase in total salivary total protein (TPC) than the hot water. In conclusion, the black tea ingestion affects the redox attributes of human saliva acutely and significantly, while the temperature of drink makes the secondary contribution.

Effect of the Teeth Whitening Procedure on the Mineral Composition of Oral Fluid

The basis of modern tooth whitening systems is the use of a whitening gel, which usually contains hydrogen peroxide or carbamide peroxide. The study included 81 patients aged 22 to 35 years with a tooth color A2 and a darker color on the Vita Classic scale. The purpose of our research was to identify a new approach to whitening teeth to improve safety and gentleness. To perform this, we assessed the effect of the tooth whitening procedure on the mineral composition of the oral fluid. A new approach to the teeth whitening procedure was to use a mouth retractor and a tool for aspirating the whitening gel, which we developed. Before the procedure, a protective film-forming aerosol, which included sodium ascorbate, was applied. After the tooth whitening procedure, the enamel was remineralized with a sealing liquid for 14 days. The concentrations of calcium and phosphorus in the oral fluid were determined using a spectrophotometer with a set of reagents (Human). The results obtained indicate that the new approach to the teeth whitening procedure contributed to less pronounced changes in the concentrations of calcium (+29.07, p < 0.001) and phosphorus (-14%, p < 0.001) in the oral fluid immediately after the procedure and in combination with the standard procedure for teeth whitening; immediately after this procedure, the calcium concentration increased by 74.4% (p < 0.001), and the phosphorus concentration decreased by 23.07% (p < 0.001). The use of remineralizing agents led to a faster recovery of the initial levels of calcium and phosphorus in the oral fluid.

Benchmarking of a microgel-reinforced hydrogel-based aqueous lubricant against commercial saliva substitutes

Xerostomia, the subjective sensation of 'dry mouth' affecting at least 1 in 10 adults, predominantly elders, increases life-threatening infections, adversely impacting nutritional status and quality of life. A patented, microgel-reinforced hydrogel-based aqueous lubricant, prepared using either dairy or plant-based proteins, has been demonstrated to offer substantially enhanced lubricity comparable to real human saliva in in vitro experiments. Herein, we present the benchmarking of in vitro lubrication performance of this aqueous lubricant, both in its dairy and vegan formulation against a range of widely available and employed commercial saliva substitutes, latter classified based on their shear rheology into "liquids", "viscous liquids" and "gels", and also had varying extensional properties. Strikingly, the fabricated dairy-based aqueous lubricant offers up to 41-99% more effective boundary lubrication against liquids and viscous liquids, irrespective of topography of the tested dry mouth-mimicking tribological surfaces. Such high lubricity of the fabricated lubricants might be attributed to their limited real-time desorption (7%) from a dry-mouth mimicking hydrophobic surface unlike the tested commercial products including gels (23-58% desorption). This comprehensive benchmarking study therefore paves the way for employing these microgel-based aqueous lubricant formulations as a novel topical platform for dry mouth therapy.

Study on the Influence of Regular Physical Activity on Children's Oral Health

The benefits of physical activities conducted systematically on the harmonious development, intellectual performance, and general health of children are unanimously accepted. This study's aim is to determine whether differences in oral health between young athletes and children not engaged in competitive sports are present. A total of 173 children aged between 6 and 17 years, 58 hockey players, 55 football players, and 60 in the control group were divided into groups according to their activity, age, and biological sex and examined for oral hygiene and dental and periodontal health, using clinically determined indices. Statistical analysis showed significant differences between the groups, with lower (better) values for athletes, regardless of age, sex, or activity. Oral hygiene showed the most relevant differences for males aged 14 to 17, as did the index for dental health. Periodontal health, on the other hand, was significantly better for females aged 6 to 13. Based on this data, the beneficial influence of regular physical activity also has an impact on oral health. Identifying the mechanisms behind this needs to be explored in depth and may be a topic for further research.

The effectiveness of cold oral stimuli in quenching postoperative thirst: A systematic review and meta-analysis

OBJECTIVE

To examine the effectiveness of cold oral stimuli in quenching postoperative thirst in patients undergoing surgery.

DESIGN

A systematic review and meta-analysis of interventional studies.

SETTING

Postoperative care units.

METHODS

Seven electronic databases (Medline, Scopus, Web of Science, PubMed, CINHAL, PsycInfo, and EMBASE) were systematically searched from their inception to January 12, 2022. The Cochrane Handbook for Systematic Reviews of Interventions was followed. Two researchers examined the study quality using the Cochrane risk of bias tools. A meta-analysis with a subgroup analysis was performed. Sensitivity analysis, funnel plots and Egger's test were used to examine publication bias.

MAIN OUTCOME MEASURE

A thirst intensity score was used to rate postoperative thirst.

RESULTS

Data were collected from 11 interventional studies for this systematic review. Eight studies underwent a meta-analysis with a total of 1504 patients. Our meta-analysis showed that the thirst intensity scores decreased in the experimental groups by 1.42 points (95% confidence interval: -2.162 to -0.684) more than those of the control groups. Subgroup analysis indicated that Asian patients and age were two factors that moderated the thirst intensity score after applying cold oral stimuli.

CONCLUSION

Cold oral stimuli were effective in mitigating postoperative thirst. Ice products such as ice cubes, or ice chips are easily available in postoperative units. When applying cold oral stimuli, health professionals should be aware of that in Asian and older patients. Cultural acceptance and physiological degeneration, respectively, may influence the thirst ratings. Future research should investigate various factors underlying the perioperative period. Network meta-analysis can be used to examine multiple strategies for thirst management.

Oral Temperature and pH Influence Dietary Nitrate Metabolism in Healthy Adults

This study tested the hypothesis that the increases in salivary and plasma [NO₂^-] after dietary NO₃^- supplementation would be greater when oral temperature and pH were independently elevated, and increased further when oral temperature and pH were elevated concurrently. Seven healthy males (mean ± SD, age 23 ± 4 years) ingested 70 mL of beetroot juice concentrate (BR, which provided ~6.2 mmol NO₃^-) during six separate laboratory visits. In a randomised crossover experimental design, salivary and plasma [NO₃^-] and [NO₂^-] were assessed at a neutral oral pH with a low (T_Lo-pH_Norm), intermediate (T_Mid-pH_Norm), and high (T_Hi-pH_Norm) oral temperature, and when the oral pH was increased at a low (T_Lo-pH_Hi), intermediate (T_Mid-pH_Hi), and high (T_Hi-pH_Hi) oral temperature. Compared with the T_Mid-pH_Norm condition (976 ± 388 µM), the mean salivary [NO₂^-] 1-3 h post BR ingestion was higher in the T_Mid-pH_Hi (1855 ± 423 µM), T_Hi-pH_Norm (1371 ± 653 µM), T_Hi-pH_Hi (1792 ± 741 µM), T_Lo-pH_Norm (1495 ± 502 µM), and T_Lo-pH_Hi (2013 ± 662 µM) conditions, with salivary [NO₂^-] also higher at a given oral temperature when the oral pH was increased (p < 0.05). Plasma [NO₂^-] was higher 3 h post BR ingestion in the T_Mid-pH_Hi, T_Hi-pH_Hi, and T_Lo-pH_Hi conditions, but not the T_Lo-pH_Norm and T_Hi-pH_Norm conditions, compared with T_Mid-pH_Norm (p < 0.05). Therefore, despite ingesting the same NO₃^- dose, the increases in salivary [NO₂^-] varied depending on the temperature and pH of the oral cavity, while the plasma [NO₂^-] increased independently of oral temperature, but to a greater extent at a higher oral pH.

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.

Impact of age on the diagnostic performance of unstimulated salivary flow rates and salivary gland ultrasound for primary Sjögren's syndrome

Background

Age-related changes and different patterns of salivary gland abnormalities according to age may affect the diagnostic performance of unstimulated salivary flow rate (USFR) and salivary gland ultrasound (SGUS) for primary Sjögren's syndrome (pSS). We aimed to evaluate the threshold and diagnostic performance of USFR and whether incorporating SGUS or replacing USFR with SGUS affects the performance of the ACR/EULAR criteria for pSS according to age.

Materials and methods

This medical chart review study included patients with suspected pSS who completed evaluations for pSS. Patients were classified based on age at pSS evaluation: elderly (≥65 years), middle-aged (40–64), and young (&lt; 40). The USFR's optimal thresholds were evaluated using the ROC curve. The diagnostic performances of the USFR and modified ACR/EULAR criteria were compared.

Results

In total, 239 pSS patients and 92 patients with idiopathic sicca syndrome were included. The cut-off of USFR ≤ 0.1 mL/min was irrelevant to age, demonstrating the best sensitivity (44.3–53.0%) and specificity (74.1–90.9%). SGUS had a significantly better AUC than USFR in the young (p &lt; 0.01) and middle-aged groups (p &lt; 0.01). The middle-aged group demonstrated better diagnostic performance of the ACR/EULAR criteria incorporating SGUS (AUC 0.957) (p &lt; 0.01) and criteria replacing USFR with SGUS (AUC 0.957) (p &lt; 0.001) compared to the original criteria (AUC 0.916). In the young and elderly groups, adding SGUS to the ACR/EULAR criteria or replacing USFR with SGUS did not significantly increase the AUC.

Conclusions

The thresholds of USFR ≤ 0.1 mL/min was optimal, irrespective of age. Using SGUS can improve diagnostic accuracy of ACR/EULAR criteria by supplementing the USFR, especially in middle-aged patients.

Novel impacts of saliva with regard to oral health

The maintenance of balanced oral homeostasis depends on saliva. A readily available and molecularly rich source of biological fluid, saliva fulfills many functions in the oral cavity, including lubrication, pH buffering, and tooth mineralization. Saliva composition and flow can be modulated by different factors, including circadian rhythm, diet, age, drugs, and disease. Recent events have revealed that saliva plays a central role in the dissemination and detection of the SARS-CoV-2 coronavirus. A working knowledge of saliva function and physiology is essential for dental health professionals.

Tusks, the extra-oral teeth

OBJECTIVE

The present review aims to: a) describe the features that support tusks in extra-oral position, and b) represent distinctive features of tusks, which provide insights into tusks adaptation to ambient conditions.

DESIGN

A comprehensive review of scientific literature relevant to tusks and comparable dental tissues was conducted.

RESULTS

The oral cavity provides a desirable condition which is conducive to tooth health. Therefore, it remains questionable how the bare (exposed) tusks resist the extra-oral conditions. The common features among tusked mammals indicate that the structural (e.g. the peculiar dentinal alignment), cellular (e.g. low or lack of cell populations in the tusk), hormonal (e.g. androgens), and behavioral traits have impact on a tusk's preservation and occurrence.

CONCLUSIONS

Understanding of bare mineralized structures, such as tusks and antlers, and their compatibility with different environments, can provide important insight into oral biology.