Saliva--the defender of the oral cavity

Caffeine weakens the astringency of epigallocatechin gallate by inhibiting its interaction with salivary proteins

The astringency of green tea is an integrated result of the synergic and antagonistic effects of individual tea components, whose mechanism is highly complex and not completely understood. Herein, we used an epigallocatechin gallate (EGCG)/caffeine (CAF)/saliva model to simulate the oral conditions during tea drinking. The effect of CAF on the interaction between EGCG and salivary proteins was first investigated using molecular docking and isothermal titration calorimetry (ITC). Then, the rheological properties and the micro-network structure of saliva were studied to relate the molecular interactions and perceived astringency. The results revealed that CAF partially occupied the binding sites of EGCG to salivary proteins, inhibiting their interaction and causing changes in the elastic network structure of the salivary film, thereby reducing astringency.

Fermented food consumption modulates the oral microbiota

Fermented food consumption is recommended for health and environmental purposes. While it is known to impact gut microbiota, further investigation is needed to establish connections with the oral microbiota. For this purpose, we investigated the effect of daily consumption of a model cheese containing 3 Lactic Acid Bacteria (LAB) species on the oral microbiota of rats following a 3-week diet. Cheese consumption transiently modifies the oral microbiota and leads to a transient persistence of LAB in the oral cavity of 1/3 of the animals. The origin of this variability was partly explained by an overrepresentation of salivary proteins involved in the response to oxidative stress in animals without LAB persistence. These findings highlight the significance of fermented foods in shaping the diversity of the oral microbiota. Additionally, they suggest that variations in the salivary proteome among individuals may influence the permissiveness of the oral microbiota towards exogenous microorganisms.

HIV Infection and Exposure Increases Cariogenic Taxa, Reduces Taxonomic Turnover, and Homogenizes Spatial Differentiation for the Supragingival Microbiome

Background

The oral microbiome comprises distinct microbial communities that colonize diverse ecological niches across the oral cavity, the composition of which are influenced by nutrient and substrate availability, host genetics, diet, behavior, age, and other diverse host and environmental factors. Unlike other densely populated human-associated microbial ecosystems (e.g., gut, urogenital), the oral microbiome is regularly and directly exposed to the external environment and is therefore likely less stable over time. Cross sectional studies of the oral microbiome capture a glimpse of this temporal dynamism, yet a full appreciation of the relative stability, robusticity, and spatial structure of the oral environment is necessary to understand the role of microbial communities in promoting health or disease.

Results

Here we investigate the spatial and temporal stability of the oral microbiome over three sampling time points in the context of HIV infection and exposure. Individual teeth were sampled from a cohort of 565 Nigerian children with varying levels of tooth decay severity (i.e., caries disease). We collected 1,960 supragingival plaque samples and characterized the oral microbiome using a metataxonomic approach targeting an approximately 478 bp region of the bacterial rpoC gene. We found that both infection and exposure to HIV have significant effects on the stability of the supragingival plaque microbiome at both the spatial and temporal scale. Specifically, we detect (1) significantly lower taxonomic turnover of the oral community among exposed and infected children compared to unexposed children, (2) we find that HIV infection homogenizes the oral community across the anterior and posterior dentition, and (3) that impaired immunity (i.e., low CD4 count) and low taxonomic turnover over time in children living with HIV is associated with higher frequency of cariogenic taxa including Streptococcus mutans.

Conclusions

Our results document substantial community fluctuations over time in children unexposed to HIV independent of oral health status. This suggests that the oral community, under typical conditions, rapidly adapts to environmental perturbations to maintain homeostasis and that long-term taxonomic rigidity is a signal of community dysfunction, potentially leading to a higher incidence of oral disease including caries.

The oral-gut microbiome axis in health and disease

The human body hosts trillions of microorganisms throughout many diverse habitats with different physico-chemical characteristics. Among them, the oral cavity and the gut harbour some of the most dense and diverse microbial communities. Although these two sites are physiologically distinct, they are directly connected and can influence each other in several ways. For example, oral microorganisms can reach and colonize the gastrointestinal tract, particularly in the context of gut dysbiosis. However, the mechanisms of colonization and the role that the oral microbiome plays in causing or exacerbating diseases in other organs have not yet been fully elucidated. Here, we describe recent advances in our understanding of how the oral and intestinal microbiota interplay in relation to their impact on human health and disease.

Dental implant considerations in patients with systemic diseases: An updated comprehensive review

BACKGROUND

Various medical conditions and the drugs used to treat them have been shown to impede or complicate dental implant surgery. It is crucial to carefully monitor the medical status and potential post-operative complications of patients with systemic diseases, particularly elderly patients, to minimize the risk of health complications that may arise.

AIM

The purpose of this study was to review the existing evidence on the viability of dental implants in patients with systemic diseases and to provide practical recommendations to achieve the best possible results in the corresponding patient population.

METHODS

The information for our study was compiled using data from PubMed, Scopus, Web of Science and Google Scholar databases and searched separately for each systemic disease included in our work until October 2023. An additional manual search was also performed to increase the search sensitivity. Only English-language publications were included and assessed according to titles, abstracts and full texts.

RESULTS

In total, 6784 studies were found. After checking for duplicates and full-text availability, screening for the inclusion criteria and manually searching reference lists, 570 articles remained to be considered in this study.

CONCLUSION

In treating patients with systemic conditions, the cost-benefit analysis should consider the patient's quality of life and expected lifespan. The success of dental implants depends heavily on ensuring appropriate maintenance therapy, ideal oral hygiene standards, no smoking and avoiding other risk factors. Indications and contraindications for dental implants in cases of systemic diseases are yet to be more understood; broader and hardcore research needs to be done for a guideline foundation.

Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS)

Background

Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is increasingly recognized as a clinicoradiological syndrome. Its etiology is diverse, encompassing a variety of triggers, including infections and metabolic abnormalities. Uniquely, MERS may present with psychiatric symptoms, such as delirium, visual hallucinations, and catatonia, posing diagnostic challenges. The variability of these neuropsychiatric symptoms necessitates early diagnosis through magnetic resonance imaging (MRI) to avoid prolonged antipsychotic treatment.

Case Presentation

This report details a case of MERS in a 39-year-old male. The patient initially presented with headache, sore throat, and abnormal laboratory results: leukocytosis, neutrophilia with a left shift, elevated C-reactive protein (CRP) levels, and hyponatremia. On the fourth day of admission, he developed severe anxiety and restlessness, exhibited thoughts of death, and reported experiencing vivid hallucinations upon closing his eyes. MRI revealed a hyperintense lesion in the corpus callosum. A lumbar puncture showed no increase in cell count or protein. The patient showed a positive response to treatment with antibiotics and olanzapine, demonstrating rapid symptomatic improvement. A follow-up MRI on the 11th day showed complete resolution of the brain lesions. Six months later, no neurological or psychiatric sequelae were noted. The patient's clinical progression and imaging findings led to a definitive diagnosis of MERS.

Conclusion

The early presentation of symptoms such as restlessness, hallucinations, and death ideation played a critical role in diagnosing MERS, with early MRI examination being instrumental in both diagnosis and preventing prolonged antipsychotic medication use.

Chitinases: expanding the boundaries of knowledge beyond routinized chitin degradation

Chitinases, enzymes that degrade chitin, have long been studied for their role in various biological processes. They play crucial roles in the moulting process of invertebrates, the digestion of chitinous food, and defense against chitin-bearing pathogens. Additionally, chitinases are involved in physiological functions in crustaceans, such as chitinous food digestion, moulting, and stress response. Moreover, chitinases are universally distributed in organisms from viruses to mammals and have diverse functions including tissue degradation and remodeling, nutrition uptake, pathogen invasion, and immune response regulation. The discovery of these diverse functions expands our understanding of the biological significance and potential applications of chitinases. However, recent research has shown that chitinases possess several other functions beyond just chitin degradation. Their potential as biopesticides, therapeutic agents, and tools for bioremediation underscores their significance in addressing global challenges. More importantly, we noted that they may be applied as bioweapons if ethical regulations regarding production, engineering and application are overlooked.

Investigation of Hydrocolloid Plant Polysaccharides as Potential Candidates to Mimic the Functions of MUC5B in Saliva

The successful substitution of complex physiological fluids, such as human saliva, remains a major challenge in drug development. Although there are a large number of saliva substitutes on the market, their efficacy is often inadequate due to short residence time in the mouth, unpleasant mouthfeel, or insufficient protection of the teeth. Therefore, systems need to be identified that mimic the functions of saliva, in particular the salivary mucin MUC5B and the unique physiological properties of saliva. To this end, plant extracts known to contain hydrocolloid polysaccharides and to have mucus-forming properties were studied to evaluate their suitability as saliva substitutes. The aqueous plant extracts of Calendula officinalis, Fucus sp. thalli, and lichenan from Lichen islandicus were examined for composition using a range of techniques, including GC-MS, NMR, SEC, assessment of pH, osmolality, buffering capacity, viscoelasticity, viscoelastic interactions with human saliva, hydrocolloid network formation, and in vitro cell adhesion. For this purpose, a physiologically adapted adhesive test was developed using human buccal epithelial cells. The results show that lichenan is the most promising candidate to mimic the properties of MUC5B. By adjusting the pH, osmolality, and buffering capacity with K2HPO4, it was shown that lichenan exhibited high cell adhesion, with a maximum detachment force that was comparable to that of unstimulated whole mouth saliva.

The Role of Sulfhydryl (Thiols) Groups in Oral and Periodontal Diseases

AIM

The sulfhydryl (thiols) group of glutathione plays an important role in the neutralization of foreign organic compounds and the reduction in peroxides. The purpose of the study is to evaluate the concentration of sulfhydryl groups in the gingival tissue of healthy individuals and those with gingivitis or periodontitis, and to examine the differences between these groups.

MATERIAL AND METHODS

To assess the concentration of sulfhydryl groups (thiols) in the gingival tissue of healthy individuals and those with gingivitis or periodontitis, we used spectrophotometric analysis using dithionitrobenzoate (DTNB) as a reagent to measure the accessible sulfhydryl groups present in gingival tissue proteins. The sample was divided into three distinct groups: individuals with periodontal health, gingivitis, and periodontitis, and different indices were used to assess the periodontal status of the participants. Next, a statistical analysis was conducted to compare the concentrations of sulfhydryl groups among the different groups of patients.

CONCLUSIONS

The results of this study showed significantly decreased levels of sulfhydryl (thiols) groups in gingival tissue from patients with gingivitis and periodontitis, compared with healthy people (control group). These results confirm the role of sulfhydryl (thiols) groups in defense against free radicals. They share a significant role in detoxification, signal transduction, apoptosis, and various other functions at the molecular level.

Are orofacial pain and xerostomia associated with differences in diet, sensory perception, appetite and enjoyment of eating?-An explorative study

BACKGROUND

Orofacial function is believed to influence an individual's diet. knowledge on appetite and enjoyment of eating in orofacially impaired individuals is scarce.

OBJECTIVE

We aimed to explore potential associations between impaired orofacial function, that is, orofacial pain, jaw function limitation and xerostomia, respectively, and diet, appetite, taste perception, as well as the enjoyment of eating.

METHODS

An online questionnaire was shared among Aarhus University's dental patients and through social media. A convenience sample of 351 individuals responded (97 men, 254 women, aged 18-86 years). Participants were divided into groups with and without orofacial pain or xerostomia based on responses. Questions about food intake, appetite, meal-related well-being and oral/general health were included. Data were analysed using Mann Whitney U tests, Spearman's correlation, Chi-square tests, and t-tests.

RESULTS

Participants with (n = 123) and without (n = 228) orofacial pain differed significantly regarding age, perceived oral/general health, frequency of consumption of for example cooked vegetables and raw whole fruit, perception of sourness, chewiness, and nausea/pain when eating (p ≤ .031). Participants with (n = 101) and without (n = 250) xerostomia differed significantly regarding perceived oral/general health, intake of prepared fruit, alcohol, ice cream/mousse/pudding, general appetite, intake of breakfast and liquid snacks, nausea/pain when eating, taste and chewiness of food (p ≤ .038).

CONCLUSION

Diet, appetite, taste and sensory perception, as well as enjoyment of eating of individuals reporting orofacial pain and/or xerostomia differed slightly to that of individuals free of such symptoms. However, due to the explorative nature of this study, the results should be interpreted with caution pending further research on potential long-term effects on nutritional status and well-being.

Dry Mouth Dilemma: A Comprehensive Review of Xerostomia in Complete Denture Wearers

Xerostomia, commonly known as dry mouth, presents a significant challenge for individuals wearing complete dentures, affecting their oral health and quality of life. This review explores the relationship between saliva and complete dentures, highlighting the varied management strategies for xerostomia. Saliva plays a critical role in denture retention, lubrication, and oral environment buffering. Complete denture wearers often experience reduced salivary flow, aggravating symptoms of xerostomia. Various management approaches are discussed, including general measures such as hydration and salivary stimulation techniques which aim to boost saliva production naturally. The use of salivary substitutes provides artificial lubrication and moisture to alleviate dry mouth discomfort. Oral lubricating devices, such as sprays, gels, and lozenges, offer relief by mimicking saliva's lubricating properties, thereby improving denture stability and comfort. This review addresses the etiology of xerostomia in complete denture wearers and explores preventive measures to reduce its impact. A comprehensive approach has been discussed for the management of xerostomia which will help to improve the oral health and well-being of complete denture wearers experiencing dry mouth.

Assessment of the Salivary Concentrations of Selected Immunological Components in Adult Patients in the Late Period after Allogeneic Hematopoietic Stem Cell Transplantation-A Translational Study

(1) The aim of the study was to analyze the salivary concentrations of lysozyme, lactoferrin, and sIgA antibodies in adult patients in the late period after allogeneic stem cell transplantation (alloHSCT). The relationship between these concentrations and the salivary secretion rate and the time elapsed after alloHSCT was investigated. The relationship between the concentrations of lysozyme, lactoferrin, and sIgA and the titer of the cariogenic bacteria S. mutans and L. acidophilus was assessed. (2) The study included 54 individuals, aged 19 to 67 (SD = 40.06 ± 11.82; Me = 39.5), who were 3 to 96 months after alloHSCT. The concentrations of lysozyme, lactoferrin, and sIgA were assessed in mixed whole resting saliva (WRS) and mixed whole stimulated saliva (WSS). (3) The majority of patients had very low or low concentrations of the studied salivary components (WRS-lysozyme: 52, lactoferrin: 36, sIgA: 49 patients; WSS-lysozyme: 51, lactoferrin: 25, sIgA: 51 patients). The levels of lactoferrin in both WRS and WSS were statistically significantly higher in the alloHSCT group than in the control group (CG) (alloHSCT patients-WRS: M = 40.18 μg/mL; WSS: M = 27.33 μg/mL; CG-WRS: M = 17.58 μg/mL; WSS: 10.69 μg/mL). No statistically significant correlations were observed between lysozyme, lactoferrin, and sIgA concentrations and the time after alloHSCT. In the group of patients after alloHSCT a negative correlation was found between the resting salivary flow rate and the concentration of lactoferrin and sIgA. The stimulated salivary flow rate correlated negatively with lactoferrin and sIgA concentrations. Additionally, the number of S. mutans colonies correlated positively with the concentration of lysozyme and sIgA. (4) The concentrations of non-specific and specific immunological factors in the saliva of patients after alloHSCT may differ when compared to healthy adults; however, the abovementioned differences did not change with the time after transplantation.

Exploring the Correlation between Salivary Spinnbarkeit and Caries Scores

INTRODUCTION

In this study, the relationship between the spinnbarkeit, i.e., the stretchability of saliva, and dental caries was investigated.

METHODS

Dentistry students were divided into a group with more than 2 decayed, missed, and filled teeth (DMFT ≥2, n = 30) and caries-free group (DMFT = 0, n = 36).

RESULTS

Unstimulated saliva flow rate, pH, and spinnbarkeit were determined. Salivary spinnbarkeit was significantly lower in the caries-prone group compared to the caries-free group (5.4 ± 3.9 mm vs. 13.5 ± 7.6 mm, respectively, p < 0.001).

CONCLUSION

This suggests that saliva with high spinnbarkeit protects better against dental caries.

Saliva Collection Methods Among Children and Adolescents: A Scoping Review

OBJECTIVE

Saliva can be used for screening and diagnostic purposes. Although multiple saliva collection methods are available, their use in children can be limited due to lack of cooperation, developmental stage, and age. The aim of this scoping review was to comprehensively appraise the different methods of saliva collection among both children and adolescents by assessing the available scientific literature.

METHODS

A literature search was performed using the databases PubMed, Embase, and Web of Science. Eligible studies on saliva collection methods among children and adolescents were included for this review.

RESULTS

The literature search identified 249 eligible articles, of which 205 had a cross-sectional study design. Four distinct saliva collection methods have surfaced: the drooling method, the absorption method, the spitting method, and the suction method. Among infants or children under the age of 6 years, the suction and absorption methods were most preferred. The drooling and spitting methods were only applicable among children above the age of 3 years. When children were not willing to cooperate, the absorption method was most feasible. In adolescents and older children, no specific method was found to be preferred over another method.

CONCLUSION

Overall, saliva collection is well tolerated by children and adolescents, with the absorption and suction methods being preferred with young and uncooperative children.

Different Group A Streptococcus pili lead to varying proinflammatory cytokine responses and virulence

The human pathogen Streptococcus pyogenes, or Group A Streptococcus (GAS), is associated with a variety of diseases ranging from mild skin and soft tissue infections to invasive diseases and immune sequelae such as rheumatic heart disease. We have recently reported that one of the virulence factors of this pathogen, the pilus, has inflammatory properties and strongly stimulates the innate immune system. Here we used a range of nonpathogenic Lactococcus lactis gain-of-function mutants, each expressing one of the major pilus types of GAS, to compare the immune responses generated by various types of fully assembled pili. In vitro assays indicated variability in the inflammatory response induced by different pili, with the fibronectin-binding, collagen-binding, T antigen (FCT)-1-type pilus from GAS serotype M6/T6 inducing significantly stronger cytokine secretion than other pili. Furthermore, we established that the same trend of pili-mediated immune response could be modeled in Galleria mellonella larvae, which possess a similar innate immune system to vertebrates. Counterintuitively, across the panel of pili types examined in this study, we observed a negative correlation between the intensity of the immune response demonstrated in our experiments and the disease severity observed clinically in the GAS strains associated with each pilus type. This observation suggests that pili-mediated inflammation is more likely to promote bacterial clearance instead of causing disruptive damages that intensify pathogenesis. This also indicates that pili may not be the main contributor to the inflammatory symptoms seen in GAS diseases. Rather, the immune-potentiating properties of the pilus components could potentially be exploited as a vaccine adjuvant.

The impact of saliva collection methods on measured salivary biomarker levels

Saliva diagnostics have become increasingly popular due to their non-invasive nature and patient-friendly collection process. Various collection methods are available, yet these are not always well standardized for either quantitative or qualitative analysis. In line, the objective of this study was to evaluate if measured levels of various biomarkers in the saliva of healthy individuals were affected by three distinct saliva collection methods: 1) unstimulated saliva, 2) chew stimulated saliva, and 3) oral rinse. Saliva samples from 30 healthy individuals were obtained by the three collection methods. Then, the levels of various salivary biomarkers such as proteins and ions were determined. It was found that levels of various biomarkers obtained from unstimulated saliva were comparable to those in chew stimulated saliva. The levels of potassium, sodium, and amylase activity differed significantly among the three collection methods. Levels of all biomarkers measured using the oral rinse method significantly differed from those obtained from unstimulated and chew-stimulated saliva. In conclusion, both unstimulated and chew-stimulated saliva provided comparable levels for a diverse group of biomarkers. However, the results obtained from the oral rinse method significantly differed from those of unstimulated and chew-stimulated saliva, due to the diluted nature of the saliva extract.

CLINICAL FINDINGS OF DENTAL DISEASE AND POTENTIAL CONTRIBUTING FACTORS IN PYGMY SLOW LORISES (NYCTICEBUS PYGMAEUS) UNDER HUMAN CARE

Dental disease is a common finding in pygmy slow lorises (Nycticebus pygmaeus) under human care, but the etiology is not fully understood. The small oral cavity in this species can make diagnosis of dental disease difficult. This retrospective study evaluated medical records and diet and husbandry protocols from 18 participating institutions with the objective of describing the signalment, clinical signs, physical exam findings, tooth type, tooth location, diagnostics used, and treatments performed to help guide care for dental disease. In addition, the study aimed to identify potential contributing factors to dental disease in this species. Of 59 animals with medical records evaluated, 42 (71.2%) had dental disease: 19 (44.2%) males, 20 (46.5%) females, and 3 (9.3%) without gender documented. Average age at onset of dental disease was 7.6 yr in males and 9 yr in females. Multiple lorises with dental disease (n = 12; 28.6%) had no premonitory clinical signs, and dental disease was found incidentally on examination. On dental examination, 30 lorises (71.4%) had evidence of gingivitis. In 13 cases skull radiographs were taken, but the majority of images (n = 8; 61.5%) were nondiagnostic for pathologic dental changes. A small proportion of cases with dental abnormalities (n = 4; 9.5%) were diagnosed using computed tomography. In total, 175 teeth were extracted from 31 patients; molars were the most frequently extracted tooth (n = 55; 31.4%). No substantial differences in diets were noted among many of the participating institutions, and not all slow lorises evaluated developed dental disease (n = 17; 28.8%). This retrospective study provides clinical findings on slow loris dental disease and guidance for the veterinary care and management of slow lorises under human care.

Comparative evaluation of mucin and total protein in periodontal disease before and after nonsurgical periodontal therapy

Background

Periodontal ailments cause a quantum leap in the biomarker profile of the saliva. This profile is, in fact, the epiphany of the scale and extent of the disease. Both gingivitis and periodontitis are chronic inflammatory diseases with a step-grade progression. The study aimed to determine the response of the host in these conditions by analyzing concentrations of salivary mucin and total protein activity, before and after nonsurgical periodontal therapy (NSPT).

Materials and Methods

Sixty adult subjects were clinically examined and divided into three groups (n = 20) according to the clinical assessment and categorized as Group I (healthy), Group II (gingivitis), and Group III (chronic periodontitis). Whole saliva was collected, and salivary mucin and total protein levels were quantitatively measured at baseline in all the groups and additionally after NSPT in Groups II and III.

Results

Levels of mucin and total protein increased in patients with gingivitis and periodontitis. There was a slight decline in mucin levels in periodontitis patients in comparison with the gingivitis group. A positive correlation was found between the respective clinical parameters of both the groups along with their levels of salivary mucin and total protein. It indicated that the response of salivary glands to increase their protective potential caused the change among the groups.

Conclusion

Periodontal diseases induce an increase in the levels of mucins and proteins, which is believed as the action of the salivary glands to protect the oral cavity and put off the chaos caused by the microorganisms.

Effect of contamination and decontamination methods on the bond strength of adhesive systems to dentin: A systematic review

INTRODUCTION

In a suitable condition, it is important to perform any dental restorative procedure using an operatory field isolated. Then, the aim of this study was to compare the bond strength of composite restorations to dentin affected by any contamination agent through a systematic review.

METHODS

This systematic review was performed following the PRISMA 2020 guidelines. The literature search was conducted until September 2022 by scanning the following databases: Embase, PubMed, Scielo, Scopus, and Web of Science. Manuscripts evaluated the bond strength of resin-based materials to permanent human dentin contaminated with blood or saliva were selected for full-text review. The risk of bias was assessed by the RoBDEMAT tool.

RESULTS

A total of 3750 papers resulted from the search from all databases. After the full-text reading, a total of 62 articles remained for the qualitative analysis. The contamination agents used were blood, saliva, and hemostatic agents. A great variety of protocols were used to contaminate the dentin surface, and the contamination process occurred in several steps of the bonding process, including before and after the etching process, after the primer application and after the adhesive application. Also, several decontamination procedures were tested, including reapplication of the etching material, rinsing with water, chlorhexidine or sodium hypochlorite and reapplication of the adhesive system.

CONCLUSION

Any contamination with blood or saliva impaired the bond strength of resin-based materials to dentin. Decontamination procedures including water-spray and reapplication of the bonding system could revert the impairment produced by the saliva or blood contamination. The use of hemostatic agents as a method of blood decontamination is not recommended.

CLINICAL SIGNIFICANCE

Clinicians should avoid contamination during a bonding procedure, otherwise, a reduction in the bond quality is expected.

The effects of endoscope placement in the hypopharynx on swallowing-related measures in healthy adults

PURPOSE

The purpose of this study was to determine whether transnasal passage of a flexible endoscope results in changes in salivary flow rate (SFR), spontaneous swallow frequency (SSF), and masticatory efficiency (ME) in healthy adults.

METHODS

Data were collected from 15 healthy adults, 20-63 years of age. SFR and SSF were measured at baseline, after endoscope insertion, and after endoscope removal. The Test of Masticating and Swallowing Solids was administered at baseline and while the endoscope was in the hypopharynx. A repeated measures ANOVA was used to determine the effect of endoscope insertion on SFR and SSF. A paired samples t-test was used to determine the effect of endoscope insertion on total mastication time and number of masticatory cycles required with a cracker bolus. Statistical significance was set at α = 0.05.

RESULTS

SFR was found to be significantly increased during endoscope placement in the hypopharynx (M = 0.471 g/min, SD = 0.175, p = 0.002) as well as following endoscope removal (M = 0.481 g/min, SD = 0.231, p = 0.004), as compared to baseline (M = 0.310 g/min, SD = 0.130). Total mastication time and number of masticatory cycles required with a cracker bolus were significantly decreased when the endoscope was present in the hypopharynx, as compared to baseline t(14) = 3.054, p = 0.009; t(14) = 3.250, p = 0.006, respectively.

CONCLUSIONS

Visualization of swallowing during FEES is an important method for objectively evaluating several anatomical and functional parameters of the pharynx and larynx. Insertion of the endoscope into the hypopharynx during FEES may stimulate salivary secretion and improve ME, which could influence interpretation of FEES and resulting clinical recommendations.

Effect of build angle, resin layer thickness and viscosity on the surface properties and microbial adhesion of denture bases manufactured using digital light processing

OBJECTIVES

To investigate differences in the surface properties and microbial adhesion of denture base resins for digital light processing (DLP) with varying resin layer thicknesses (LT), build angles (BA), and resin viscosities.

METHODS

Two denture base resins for DLP with different viscosities (high and low) were used to prepare disk specimens applying two manufacturing parameters: 1) LT (50 or 100 μm) and 2) BA (0-, 45-, and 90-degree). Surface roughness and contact angle values were measured on the test surfaces (n=10 per group). Streptococcus oralis and Candida albicans absorbance was measured to assess microorganism attachment (n=6 per group). A three-way analysis of variance (ANOVA) was conducted, considering the main effects and their interactions (viscosity, LT, and BA). Post-hoc multiple pairwise comparisons were performed. All data were analyzed at a level of significance (P) of 0.05.

RESULTS

LT and BA significantly affected the surface roughness and contact angle of the specimens, depending on resin viscosity (P<.001). Absorbance measurement showed no significant interaction between the three factors (P>.05). However, significant interactions were observed between viscosity and BA (P<.05) and between LT and BA (P<.05).

CONCLUSIONS

Regardless of the viscosity and LT, discs with a 0-degree BA showed the least roughness. High-viscosity specimens fabricated with a 0-degree BA had the lowest contact angle. Regardless of the LT and viscosity, discs with a 0-degree BA showed the lowest S. oralis attachment. Attachment of C. albicans was the least on the disk with 50 μm LT, irrespective of the viscosity.

CLINICAL SIGNIFICANCE

Clinicians should consider the effects of LT and BA on surface roughness, contact angle, and microbial adhesion of DLP-generated dentures, which can differ depending on resin viscosity. A 50 μm LT and 0-degree BA can be used with a high-viscosity resin to fabricate denture bases with less microbial adhesion.

Salivary Antimicrobial Peptide Histatin-5 Does Not Display Zn(II)-Dependent or -Independent Activity against Streptococci

Histatin-5 (Hst5) is a member of the histatin superfamily of cationic, His-rich, Zn(II)-binding peptides in human saliva. Hst5 displays antimicrobial activity against fungal and bacterial pathogens, often in a Zn(II)-dependent manner. In contrast, here we showed that under in vitro conditions that are characteristic of human saliva, Hst5 does not kill seven streptococcal species that normally colonize the human oral cavity and oropharynx. We further showed that Zn(II) does not influence this outcome. We then hypothesized that Hst5 exerts more subtle effects on streptococci by modulating Zn(II) availability. We initially proposed that Hst5 contributes to nutritional immunity by limiting nutrient Zn(II) availability and promoting bacterial Zn(II) starvation. By examining the interactions between Hst5 and Streptococcus pyogenes as a model Streptococcus species, we showed that Hst5 does not influence the expression of Zn(II) uptake genes. In addition, Hst5 did not suppress growth of a ΔadcAI mutant strain that is impaired in Zn(II) uptake. These observations establish that Hst5 does not promote Zn(II) starvation. Biochemical examination of purified peptides further confirmed that Hst5 binds Zn(II) with high micromolar affinities and does not compete with the AdcAI high-affinity Zn(II) uptake protein for binding nutrient Zn(II). Instead, we showed that Hst5 weakly limits the availability of excess Zn(II) and suppresses Zn(II) toxicity to a ΔczcD mutant strain that is impaired in Zn(II) efflux. Altogether, our findings led us to reconsider the function of Hst5 as a salivary antimicrobial agent and the role of Zn(II) in Hst5 function.

Saliva Metabolomic Profile in Dental Medicine Research: A Narrative Review

Metabolomic research tends to increase in popularity over the years, leading to the identification of new biomarkers related to specific health disorders. Saliva is one of the most newly introduced and systematically developed biofluids in the human body that can serve as an informative substance in the metabolomic profiling armamentarium. This review aims to analyze the current knowledge regarding the human salivary metabolome, its alterations due to physiological, environmental and external factors, as well as the limitations and drawbacks presented in the most recent research conducted, focusing on pre—analytical and analytical workflows. Furthermore, the use of the saliva metabolomic profile as a promising biomarker for several oral pathologies, such as oral cancer and periodontitis will be investigated.

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.

Epidermolysis bullosa in oral health: clinical manifestations and salivary alterations

Epidermolysis bullosa (EB) is an inherited disease characterized by the fragility of the skin and mucous membranes. All types/subtypes of EB can lead to alterations in the mouth and glands.

OBJECTIVE

To evaluate clinical manifestations of EB on the oral mucosa and alterations in salivary flow.

MATERIALS AND METHODS

Sociodemographic and clinical data were obtained from EB individuals. The salivary flow analysis was performed in EB and in non-EB patients. Fischer's exact test was applied to the qualitative variables, and the Mann-Whitney test was applied to the quantitative data.

RESULTS

A total of 11 cases of EB were evaluated, and 3 types of EB were diagnosed (recessive dystrophic-RDEB; junctional-JEB; and simplex-EBS). Only individuals with RDEB or JEB showed the oral manifestation of the disease. The most affected sites were the lips (54%), hard palate (36%), and oral mucosa (27%). Ulcer and ankyloglossia were diagnosed in all RDEB cases. Regarding salivary flow, an intragroup comparison revealed an increase in stimulated versus unstimulated collection in the control sample (p = 0.0064). The EB group showed no difference (p = 0.6086). We also observed no differences in salivary volume between the control and EB groups (p = 0.7117 and p = 0.5557, unstimulated and stimulated flows, respectively).

CONCLUSIONS

No oral manifestations were observed in EBS subjects. It is unclear whether individuals with EB are predisposed to manifest hyposalivation.

CLINICAL RELEVANCE

Severe cases of EB show broad alterations in the oral mucosa, whereas the saliva needs to be better evaluated.

Saliva - a new opportunity for fluid biopsy

Saliva is a complex biological fluid with a variety of biomolecules, such as DNA, RNA, proteins, metabolites and microbiota, which can be used for the screening and diagnosis of many diseases. In addition, saliva has the characteristics of simple collection, non-invasive and convenient storage, which gives it the potential to replace blood as a new main body of fluid biopsy, and it is an excellent biological diagnostic fluid. This review integrates recent studies and summarizes the research contents of salivaomics and the research progress of saliva in early diagnosis of oral and systemic diseases. This review aims to explore the value and prospect of saliva diagnosis in clinical application.

Fat-soluble vitamin and phytochemical metabolites: Production, gastrointestinal absorption, and health effects

Consumption of diets rich in fruits and vegetables, which provide some fat-soluble vitamins and many phytochemicals, is associated with a lower risk of developing certain degenerative diseases. It is well accepted that not only the parent compounds, but also their derivatives formed upon enzymatic or nonenzymatic transformations, can produce protective biological effects. These derivatives can be formed during food storage, processing, or cooking. They can also be formed in the lumen of the upper digestive tract during digestion, or via metabolism by microbiota in the colon. This review compiles the known metabolites of fat-soluble vitamins and fat-soluble phytochemicals (FSV and FSP) that have been identified in food and in the human digestive tract, or could potentially be present based on the known reactivity of the parent compounds in normal or pathological conditions, or following surgical interventions of the digestive tract or consumption of xenobiotics known to impair lipid absorption. It also covers the very limited data available on the bioavailability (absorption, intestinal mucosa metabolism) and summarizes their effects on health. Notably, despite great interest in identifying bioactive derivatives of FSV and FSP, studying their absorption, and probing their putative health effects, much research remains to be conducted to understand and capitalize on the potential of these molecules to preserve health.

Isolation of salivary cell-free DNA for cancer detection

Saliva is an emerging source of disease biomarkers, particularly for cancers of the head and neck. Although analysis of cell-free DNA (cfDNA) in saliva holds promise as a liquid biopsy for cancer detection, currently there are no standardized methodologies for the collection and isolation of saliva for the purposes of studying DNA. Here, we evaluated various saliva collection receptacles and DNA purification techniques, comparing DNA quantity, fragment size, source, and stability. Then, using our optimized techniques, we tested the ability to detect human papillomavirus (HPV) DNA- a bona fide cancer biomarker in a subset of head and neck cancers- from patient saliva samples. For saliva collection, we found that the Oragene OG-600 receptacle yielded the highest concentration of total salivary DNA as well as short fragments <300 bp corresponding to mononucleosomal cell-free DNA. Moreover, these short fragments were stabilized beyond 48 hours after collection in contrast to other saliva collection receptacles. For DNA purification from saliva, the QIAamp Circulating Nucleic Acid kit yielded the highest concentration of mononucleosome-sized DNA fragments. Freeze-thaw of saliva samples did not affect DNA yield or fragment size distribution. Salivary DNA isolated from the OG-600 receptacle was found to be composed of both single and double-stranded DNA, including mitochondrial and microbial sources. While levels of nuclear DNA were consistent over time, levels of mitochondrial and microbial DNA were more variable and increased 48 hours after collection. Finally, we found that HPV DNA was stable in OG-600 receptacles, was reliably detected within the saliva of patients with HPV-positive head and neck cancer, and was abundant among mononucleosome-sized cell-free DNA fragments. Our studies have defined optimal techniques for isolating DNA from saliva that will contribute to future applications in liquid biopsy-based cancer detection.

Analysis of IGHA1 and other salivary proteins post half marathon in female participants

Background

High-intensity exercise (HIE), such as that in marathons and triathlons, suppresses transient local and systemic immunity. Serum and salivary immunoglobulin heavy constant alpha 1 (IGHA1) are major markers of immunosuppression by HIE. Although much is known about the systemic immunosuppressive response, little is known about its local response in the oral cavity, lungs, bronchial tubes, and skin. The oral cavity allows bacteria or viruses to enter the body. Saliva covers the epidermis of the oral cavity and plays an important role in the local stress response by preventing infection. In this study, we examined the properties of saliva secreted during the local stress response for half-marathon (HM) induced IGHA1 protein expression using quantitative proteomics.

Methods

The Exercise Group (ExG) (19 healthy female university students) participated in a HM race. The Non-Exercise Group (NExG) (16 healthy female university students) did not participate in the ExG. The ExG saliva samples were collected 1 h pre and 2 h and 4 h post-HM. The NExG saliva samples were collected at the same time intervals. The saliva volume, protein concentration, and relative IGHA1 expression were analyzed. In addition, 1 h pre and 2 h post- HM saliva samples were analyzed by iTRAQ. The identified factors in iTRAQ were analyzed for the ExG and the NExG using western blotting.

Results

We identified kallikrein 1 (KLK1), immunoglobulin kappa chain (IgK), and cystatin S (CST4) as suppression factors, as well as IGHA1, which has been reported to be an immunological stress marker. IGHA1 (p = 0.003), KLK1 (p = 0.011), IGK (p = 0.002), and CST4 (p = 0.003) were suppressed 2 h post-HM compared with their levels pre HM, and IGHA1 (p < 0.001), KLK1 (p = 0.004), and CST4 (p = 0.006) were suppressed 4 h post-HM. There was also a positive correlation between IGHA1, IGK, and CST4 levels at 2 and 4 h post-HM. In addition, KLK1 and IGK levels at 2 h post-HM were positively correlated.

Conclusion

Our study demonstrated that the salivary proteome is regulated, and antimicrobial proteins are suppressed post-HM. These results suggest that oral immunity was transiently suppressed post-HM. The positive correlation of each protein at 2 and 4 h post-HM suggests that the suppressed state was similarly regulated up to 4 h after a HM. The proteins identified in this study may have applications as stress markers for recreational runners and individuals who perform moderate to HIE on a regular basis.

A human monoclonal antibody bivalently binding two different epitopes in streptococcal M protein mediates immune function

Group A streptococci have evolved multiple strategies to evade human antibodies, making it challenging to create effective vaccines or antibody treatments. Here, we have generated antibodies derived from the memory B cells of an individual who had successfully cleared a group A streptococcal infection. The antibodies bind with high affinity in the central region of the surface-bound M protein. Such antibodies are typically non-opsonic. However, one antibody could effectively promote vital immune functions, including phagocytosis and in vivo protection. Remarkably, this antibody primarily interacts through a bivalent dual-Fab cis mode, where the Fabs bind to two distinct epitopes in the M protein. The dual-Fab cis-binding phenomenon is conserved across different groups of M types. In contrast, other antibodies binding with normal single-Fab mode to the same region cannot bypass the M protein's virulent effects. A broadly binding, protective monoclonal antibody could be a candidate for anti-streptococcal therapy. Our findings highlight the concept of dual-Fab cis binding as a means to access conserved, and normally non-opsonic regions, regions for protective antibody targeting.

Saliva and Plasma Neutralizing Activity Induced by the Administration of a Third bnt162b2 Vaccine Dose

The BNT162b2 vaccine induces neutralizing activity (NA) in serum, but no data are available on whether a third-dose activates specific-immunity within the oral mucosa, representing the primary route of viral-entry. To carefully address this issue, we investigated if such immunity is boosted by SARS-CoV-2-infection; how long it is maintained over-time; and if it protects against the SARS-CoV-2 lineage B.1 (EU) and the emerging Delta and Omicron variants. NA was measured in plasma and saliva samples from: uninfected SARS-CoV-2-Vaccinated (SV), subjects infected prior to vaccination (SIV), and subjects who were infected after the second (SIV2) or the third (SIV3) vaccine dose. Samples were collected immediately before (T0), 15 days (T1), and 90 days (T2) post third-dose administration (SV and SIV), or 15 days post-infection (SIV2 and SIV3). In all the enrolled groups, NA in plasma and saliva: (i) was higher against EU compared to the other variants at all time-points (SV: T0 and T1, EU vs. both Delta and Omicron p < 0.001; T2 p < 0.01) (SIV: T0, EU vs. Delta p < 0.05; EU vs. Omi p < 0.01; T1 and T2 EU vs. Delta p < 0.01; EU vs. Omi p < 0.001); (ii) was boosted by the administration of the third dose; iii) declined over-time, albeit being detectable in almost all subjects at T2. The monitoring of NA over time will be important in clarifying if different NA levels may influence either acquisition or course of infection to properly plan the timing of a fourth vaccine dose administration.

Lactoferrin and the development of salivary stones: a pilot study

Salivary stones (sialoliths) are calcified structures located in the ductal system of the major salivary glands. Their exact cause is not clear but in general they are characterized by concentric inorganic (hydroxyapatite) layers. The formation is a slow intermittent process which may result in enlargement of the sialolith causing obstruction of saliva secretion resulting in mealtime related pain and swelling of the affected salivary gland. Various studies reported the presence of organic material such as proteins and lipids in the core of sialoliths. In the present study the protein composition of twenty submandibular sialoliths was analyzed. It was found that proteins contributed on average 5% to the dry weight of submandibular stones whereby small salivary stones contained more extractable proteins than large salivary stones. Using a combination of SDS-PAGE gel electrophoresis and Western blotting, we identified α-amylase (in all stones; 100%), lysozyme (95%), lactoferrin (85%), secretory-IgA (75%), MUC7 (60%), complement C4 (60%) and C-reactive protein (35%). The presence, and the combinations, of lactoferrin, lysozyme, s-IgA and α-amylase in sialoliths was confirmed by ELISA. The gradually increasing size of a sialolith might provoke a local inflammatory response in the duct of the submandibular gland whereby the relatively low concentrations of lactoferrin and lysozyme may originate from neutrophils. The interaction of lactoferrin with s-IgA could contribute to the accumulation of lactoferrin in sialoliths. In summary, these results suggest a new pathophysiological role for lactoferrin, in the formation of sialoliths.

Lactoferrin and the development of salivary stones: a pilot study

Salivary stones (sialoliths) are calcified structures located in the ductal system of the major salivary glands. Their exact cause is not clear but in general they are characterized by concentric inorganic (hydroxyapatite) layers. The formation is a slow intermittent process which may result in enlargement of the sialolith causing obstruction of saliva secretion resulting in mealtime related pain and swelling of the affected salivary gland. Various studies reported the presence of organic material such as proteins and lipids in the core of sialoliths. In the present study the protein composition of twenty submandibular sialoliths was analyzed. It was found that proteins contributed on average 5% to the dry weight of submandibular stones whereby small salivary stones contained more extractable proteins than large salivary stones. Using a combination of SDS-PAGE gel electrophoresis and Western blotting, we identified α-amylase (in all stones; 100%), lysozyme (95%), lactoferrin (85%), secretory-IgA (75%), MUC7 (60%), complement C4 (60%) and C-reactive protein (35%). The presence, and the combinations, of lactoferrin, lysozyme, s-IgA and α-amylase in sialoliths was confirmed by ELISA. The gradually increasing size of a sialolith might provoke a local inflammatory response in the duct of the submandibular gland whereby the relatively low concentrations of lactoferrin and lysozyme may originate from neutrophils. The interaction of lactoferrin with s-IgA could contribute to the accumulation of lactoferrin in sialoliths. In summary, these results suggest a new pathophysiological role for lactoferrin, in the formation of sialoliths.

Peri-implant Bone Healing: Its Basic Osteogenesis and Biomarkers

The continuous sequence of bone healing phases starts off with osteoconduction to the implant surface, depending on the migration of osteogenic cells. Osteoneogenesis ensues resulting in a mineralised interfacial matrix and is followed by bone remodelling to the implant interface at discrete sites. Dental implant drilling procedure and placement produce osseous defect which is filled by blood. Within seconds, blood proteins are adsorbed onto the implant surface and platelets are activated resulting in the release of cytokines and growth factors. Further platelet aggregation initiates osteoconduction to the surface, followed by osteoneogenesis, forming an extracellular matrix. Subsequently, remodelling creates a bone to implant interface which can be explained through distance and contact osteogenesis. The dental implant surface has been shown to influence osteoconduction by modifying protein properties and adsorption around the implant. Salivary biomarkers may be considered as a specific and sensitive diagnostic tool to detect these changes in protein expressions after implant placement. Thus, the purpose of this narrative review is to provide a detailed account of the bone healing mechanism associated with dental implant placement, as well as how the implant surface architecture and protein release play a role in bone healing, and the potential use of saliva to detect these biomarkers.

Prolonged mask wearing does not alter the oral microbiome, salivary flow rate or gingival health status – A pilot study

The COVID-19 pandemic has resulted in the widespread use of N95 respirators and surgical masks, with anecdotal reports among healthcare providers and the public of xerostomia, halitosis, and gingivitis, a consortium of symptoms colloquially termed “mask mouth”. However, this has not been scientifically verified. The aim of this study was to assess changes in salivary flow rate, gingival health status and oral microbiome associated with prolonged mask use. A total of 25 dental students (mean age = 26.36 ± 1.58) were included in the study and evaluated at three time points: T1, at the end of at least 2 months of full-day mask wear (7.26 ± 1.56 hours/day); T2, at the end of a period of minimal mask use (1.13 ± 1.13 hours/day); and T3, at the end of 2-3 weeks of resuming full-day mask wear (6.93 ± 1.80 hours/day). Unstimulated whole saliva (UWS) flow rate, xerostomia (on a quantitative scale of 10), gingival index (GI) and plaque index (PI) were assessed at each time point. The salivary microbiome was characterized using 16S rRNA gene sequencing. Overall, UWS flow rates were normal (mean of 0.679 ml/min) and xerostomia, PI and GI scores were low (Mean of 3.11, 0.33 and 0.69, respectively) with no significant differences as a result of prolonged mask wearing. Similarly, there were no significant microbial changes at a false discovery rate (FDR) ≤ 0.05. However, some trends were identified using a nominal p-value cut-off of ≤ 0.01, namely Gemella sanguinis, Streptococcus sp. Oral taxon 066 and Oral taxon 058 were associated with prolonged mask wear. Trends were also seen by gender, race and age, for example an increase in P. gingivalis and P. intermedia with age. In conclusion, we found no evidence that prolonged mask wear adversely affects oral health. The findings support that the oral microbiome of healthy individuals is resilient.

Associations between salivary cytokines and oral health, age, and sex in healthy children

Human saliva is a complex fluid containing proteins such as salivary cytokines, which can be used for diagnostic purposes, particularly among the pediatric population. This study aimed to assess the concentrations of salivary cytokines in healthy children and adolescents and determine their associations with age, sex, and oral and dental findings. Healthy children and adolescents aged 4–18 years were enrolled in this cross-sectional study. The concentrations of the following salivary cytokines were measured by Luminex technology: IFN-γ, IL-1α, IL-1β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, IP-10, TNF-α, and VEGF-A. Additionally, oral and dental parameters were recorded using a standardized protocol. A total of 128 participants (mean age, 10.7 years; males, 50.8%) were enrolled. The levels of 1β, IL-6, IL-8, and IL-10 were significantly higher in those with gingivitis. Increased salivary flow rates were negatively correlated with IL-1α, IL-1β, IL-6, IL-8, IL-10, TNF-α, and VEGF-A concentrations. The findings of this study showed that the concentrations of most of the salivary cytokines were positively correlated with age and the presence of oral pathologies (such as gingivitis and caries) and negatively correlated with salivary flow rate.

Sci-Seq of Human Fetal Salivary Tissue Introduces Human Transcriptional Paradigms and a Novel Cell Population

Multiple pathologies and non-pathological factors can disrupt the function of the non-regenerative human salivary gland including cancer and cancer therapeutics, autoimmune diseases, infections, pharmaceutical side effects, and traumatic injury. Despite the wide range of pathologies, no therapeutic or regenerative approaches exist to address salivary gland loss, likely due to significant gaps in our understanding of salivary gland development. Moreover, identifying the tissue of origin when diagnosing salivary carcinomas requires an understanding of human fetal development. Using computational tools, we identify developmental branchpoints, a novel stem cell-like population, and key signaling pathways in the human developing salivary glands by analyzing our human fetal single-cell sequencing data. Trajectory and transcriptional analysis suggest that the earliest progenitors yield excretory duct and myoepithelial cells and a transitional population that will yield later ductal cell types. Importantly, this single-cell analysis revealed a previously undescribed population of stem cell-like cells that are derived from SD and expresses high levels of genes associated with stem cell-like function. We have observed these rare cells, not in a single niche location but dispersed within the developing duct at later developmental stages. Our studies introduce new human-specific developmental paradigms for the salivary gland and lay the groundwork for the development of translational human therapeutics.

Antimicrobial peptides: Defending the mucosal epithelial barrier

The recent epidemic caused by aerosolized SARS-CoV-2 virus illustrates the importance and vulnerability of the mucosal epithelial barrier against infection. Antimicrobial proteins and peptides (AMPs) are key to the epithelial barrier, providing immunity against microbes. In primitive life forms, AMPs protect the integument and the gut against pathogenic microbes. AMPs have also evolved in humans and other mammals to enhance newer, complex innate and adaptive immunity to favor the persistence of commensals over pathogenic microbes. The canonical AMPs are helictical peptides that form lethal pores in microbial membranes. In higher life forms, this type of AMP is exemplified by the defensin family of AMPs. In epithelial tissues, defensins, and calprotectin (complex of S100A8 and S100A9) have evolved to work cooperatively. The mechanisms of action differ. Unlike defensins, calprotectin sequesters essential trace metals from microbes, which inhibits growth. This review focuses on defensins and calprotectin as AMPs that appear to work cooperatively to fortify the epithelial barrier against infection. The antimicrobial spectrum is broad with overlap between the two AMPs. In mice, experimental models highlight the contribution of both AMPs to candidiasis as a fungal infection and periodontitis resulting from bacterial dysbiosis. These AMPs appear to contribute to innate immunity in humans, protecting the commensal microflora and restricting the emergence of pathobionts and pathogens. A striking example in human innate immunity is that elevated serum calprotectin protects against neonatal sepsis. Calprotectin is also remarkable because of functional differences when localized in epithelial and neutrophil cytoplasm or released into the extracellular environment. In the cytoplasm, calprotectin appears to protect against invasive pathogens. Extracellularly, calprotectin can engage pathogen-recognition receptors to activate innate immune and proinflammatory mechanisms. In inflamed epithelial and other tissue spaces, calprotectin, DNA, and histones are released from degranulated neutrophils to form insoluble antimicrobial barriers termed neutrophil extracellular traps. Hence, calprotectin and other AMPs use several strategies to provide microbial control and stimulate innate immunity.

Streptococcus oralis Employs Multiple Mechanisms of Salivary Mucin Binding That Differ Between Strains

Streptococcus oralis is an oral commensal and opportunistic pathogen that can enter the bloodstream and cause bacteremia and infective endocarditis. Here, we investigated the mechanisms of S. oralis binding to oral mucins using clinical isolates, isogenic mutants and glycoconjugates. S. oralis bound to both MUC5B and MUC7, with a higher level of binding to MUC7. Mass spectrometry identified 128 glycans on MUC5B, MUC7 and the salivary agglutinin (SAG). MUC7/SAG contained a higher relative abundance of Lewis type structures, including Lewis b/y, sialyl-Lewis a/x and α2,3-linked sialic acid, compared to MUC5B. S. oralis subsp. oralis binding to MUC5B and MUC7/SAG was inhibited by Lewis b and Lacto-N-tetraose glycoconjugates. In addition, S. oralis binding to MUC7/SAG was inhibited by sialyl Lewis x. Binding was not inhibited by Lacto-N-fucopentaose, H type 2 and Lewis x conjugates. These data suggest that three distinct carbohydrate binding specificities are involved in S. oralis subsp. oralis binding to oral mucins and that the mechanisms of binding MUC5B and MUC7 differ. Efficient binding of S. oralis subsp. oralis to MUC5B and MUC7 required the gene encoding sortase A, suggesting that the adhesin(s) are LPXTG-containing surface protein(s). Further investigation demonstrated that one of these adhesins is the sialic acid binding protein AsaA.

Salivary Assessments in Post-Liver Transplantation Patients

Saliva is in the first line of the body's defense mechanism. In order to better understand how liver transplantation impacts salivary biochemistry, the aim of this cross-sectional study was to explore variations of salivary markers for oral health in post-liver transplantation patients, as compared with systemically healthy dental outpatients (controls). In this case, 26 patients were enrolled in each group, with similar socio-demographic characteristics. Unstimulated whole saliva was collected; total protease activity and total protein content were measured. The oral health in both groups was assessed using a self-report oral health questionnaire. Data were analyzed using parametric and nonparametric tests. Comparable results were recorded in terms of salivary protein and protease activity assessments. In post-liver transplantation group, positive correlation was found between the salivary pH level and the salivary secretion rate (r = 0.39; p = 0.04). With respect to self-reported oral health, there were no significant differences between the two groups, except for dental and oral care habits, the controls reporting more frequently use of dental floss and mouthwash (p = 0.02, and p = 0.003, respectively). Considering the high risk for developing systemic complications after liver transplantation, oral health care is an important issue to be addressed, salivary investigations representing powerful tool for disease changes monitoring.

Confounding factors in the assessment of oral mucositis in head and neck cancer

Treatment of locally advanced head and neck carcinoma not amenable for surgical resection or resected with high-risk features is usually based on (chemo-)radiation treatment. Oral mucositis represents one of the main side effects of (chemo-)radiation, with an important impact on quality of life and causing approximately 20% of early interruption of treatment, leading to a suboptimal dose administered. Treatment and prevention of oral mucositis have a central role in the therapeutic pathways of head and neck cancer patients but remains quite challenging. Although extensive research is conducted to identify interventions for the management of mucositis, very few interventions had sufficient evidence to generate an international expert consensus. This may be partially explained by confounding factors that could influence the development and assessment of oral mucositis. Little is known about the confounding factors of oral mucositis, which, if not well balanced in an experimental study, could lead to non-solid results. The current paper aims to review the main oral mucositis confounding factors related to head and neck cancer patients.

In Vivo Transfection of Rat Salivary Glands With Fluorescently Tagged Aquaporin-5 Channel DNA

Background 

The acinar cells of salivary glands are responsible for most saliva production and are, unfortunately, h­­ighly radiosensitive. As such, dry mouth or xerostomia is an adverse effect experienced by half of head and neck cancer patients treated with radiation. We evaluate a novel method of gene transfection of aquaporin channels to rat salivary glands.

Materials and methods

A green fluorescent protein (GFP)-tagged human Aquaporin-5 (AQP5) cDNA sequence cloned into a pCMV6-AC-GFP vector was complexed with lipofectamine 2000. One submandibular gland of the anesthetized rats was injected with the complexed cDNA and lipid solution under ultrasound guidance, while the opposite gland was injected with the vehicle control. The animals were sacrificed between 24 to 48 hours post-injection. The salivary glands were removed and evaluated via fluorescence imaging. Western blot assays were also performed to determine AQP5 cDNA expression.

Results 

In the experiments, the submandibular glands were identified and injected under ultrasound guidance. Four control glands and eight experimental glands were evaluated. The cDNA was expressed successfully and variably within the experimental glands, noting greater intensity along the cell surface consistent with appropriate trafficking of the AQP5 channel. Western blot analysis demonstrated variable expression in the experimental sample with no expression in the control sample. Several glands across the groups showed mild to moderate interstitial edema or inflammation.

Conclusion 

In this study, we demonstrate an alternative in vivo transfection method via lipofection and demonstrate the successful expression of the AQP5 channel in rat salivary gland tissue.

Systemic immune response development in Albino rats after retrograde instillation of COVID-19 vaccine to submandibular salivary gland: An experimental study

Objective

This study aimed to investigate whether using the submandibular gland duct (SMD) as an alternative mucosal route for vaccine administration induced anti-COVID-19 specific immunity.

Material and methods

Forty rats were randomized equally into four groups; Group I: Rats did not receive any intervention. Group II: Rats were subjected to intramuscular (IM) injection of COVID-19 vaccine. Group III: Rats were subjected to ductal cannulation by retrograde instillation of sterile saline into right SMD. Group IV: Rats in this group who had 0.5 ml of COVID-19 vaccine retrogradely injected into the right SMD. Subsequently, rats were examined for anti-COVID-19 specific antibodies (IgG). Also, light microscopic observation of glandular changes and immunohistochemical staining for CD20 was performed.

Results

The obtained results demonstrated a significant increase in anti-COVID-19 IgG levels in all rats vaccinated via intraductal immunization (group IV) compared to group II. Histologically, ectopic follicles were found within the glandular lobules of the inoculated submandibular gland (SMG) in group IV. In addition, the nearby lymph node in group IV demonstrated reactive follicle characteristics in the form of activated secondary follicles with germinal centers (GCs). Immunohistochemically, CD20 was localized in group IV in GCs of the ectopic lymphoid tissue and the nearby lymph nodes while group I, group II, and III demonstrated negative immunoreactivity.

Conclusion

The immune response demonstrated by intraductal SG immunization is generally more significant than that elicited by IM inoculation of the same vaccine.

•

Salivary gland intraductal vaccination developed a systemic immune response.

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High antibody levels are obtained via salivary glands intraductal vaccination.

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Salivary glands are a potential mucosal route for administering vaccines.

Site- and Time-Dependent Compositional Shifts in Oral Microbiota Communities

Objectives

The oral microbiota plays a significant role in oral health. The present study aims to characterize variations in the oral microbiota relative to the collection site, the dynamics of biofilm accumulation, and inherent inter-individual differences.

Methods

Whole stimulated saliva and tooth biofilm samples from the 16 defined tooth regions were collected after 1, 2, or 3 days without oral hygiene (accumulation time) in six healthy adults with no signs of active caries or periodontal disease. The routines and conditions before and between sample collections were carefully standardized. Genomic DNA was extracted, and the V3-V4 regions of the 16S rRNA gene were amplified by PCR and sequenced on an Illumina MiSeq platform. Sequences were quality controlled, amplicon sequence variants (ASVs) were clustered, and taxonomic allocation was performed against the expanded Human Oral Microbiome Database (eHOMD). Microbial community profiles were analyzed by multivariate modeling and a linear discriminant analysis (LDA) effect size (LEfSe) method.

Results

The overall species profile in saliva and tooth biofilm differed between participants, as well as sample type, with a significantly higher diversity in tooth biofilm samples than saliva. On average, 45% of the detected species were shared between the two sample types. The microbiota profile changed from the most anterior to the most posterior tooth regions regardless of whether sampling was done after 1, 2, or 3 days without oral hygiene. Increasing accumulation time led to higher numbers of detected species in both the saliva and region-specific tooth biofilm niches.

Conclusion

The present study confirms that the differences between individuals dominate over sample type and the time abstaining from oral hygiene for oral microbiota shaping. Therefore, a standardized accumulation time may be less important for some research questions aiming at separating individuals. Furthermore, the amount of DNA is sufficient if at least two teeth are sampled for microbiota characterization, which allows a site-specific characterization of, for example, caries or periodontitis.

A Review on Xerostomia and Its Various Management Strategies: The Role of Advanced Polymeric Materials in the Treatment Approaches

The medical term xerostomia refers to the subjective sensation of oral dryness. The etiology seems to be multifactorial with the most frequently reported causes being the use of xerostomic medications, neck and head radiation, and systematic diseases (such as Sjögren’s syndrome). Xerostomia is associated with an increased incidence of dental caries, oral fungal infections, and difficulties in speaking and chewing/swallowing, which ultimately affect the oral health-related quality of life. The development of successful management schemes is regarded as a highly challenging project due to the complexity of saliva. This is why, in spite of the fact that there are therapeutic options aiming to improve salivary function, most management approaches are alleviation-oriented. In any case, polymers are an integral part of the various formulations used in every current treatment approach, especially in the saliva substitutes, due to their function as thickening and lubricating agents or, in the case of mucoadhesive polymers, their ability to prolong the treatment effect. In this context, the present review aims to scrutinize the literature and presents an overview of the role of various polymers (or copolymers) on either already commercially available formulations or novel drug delivery systems currently under research and development.

Oral microbiota in xerostomia patients - A preliminary study

Background/purpose

The estimated prevalence of xerostomia (lack of saliva) ranges from 10% to 50% of the general population. The oral cavity provides a multivariant environmental habitat to over 700 species of bacteria and fungi. We hypothesized that xerostomia will alter the composition of oral microbiota.

Material and methods

Nineteen xerostomia patients and 10 healthy normal volunteers were studied for the oral microbiota. Gingival plaques were collected and microbiota were detected using bacterial 16S ribosomal RNA and analyzed based on the levels of phylum and class.

Results

In all cases, phyla of Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria, and Proteobacteria make up to 100% of oral microbiota at phylum level. Analyzing individual phylum, presence of Bacteroidetes in xerostomia patients and normal subjects were 23.12 ± 2.56% and 23.23 ± 2.58%, respectively. Mean percentage presence of Firmicutes phylum in xerostomia patients and normal subjects were 18.94 ± 1.83% and 14.06 ± 0.98%, respectively. Statistically significant difference was not observed between xerostomia patients and normal subjects in this study.

Conclusion

These observations revealed obvious but not statistically significant changes in oral major microorganism phylum between xerostomia patients and normal subjects in this study. More samples are needed to verify the current results and to use oral microbiota as a tool in the diagnosis of xerostomia.

Amino Acids May Have Protective Effects on Salivary Glands of 5-FU-administered Mice

BACKGROUND/AIM

This study aimed to identify the most useful components of Elental^® in the treatment of 5-fluorouracil (FU)-induced mucositis and salivary gland atrophy in mice.

MATERIALS AND METHODS

Mice (except the control group) were intraperitoneally injected with 5-FU. The mice received saline (control group and 5-FU group), dextrin (Dextrin group), amino acids (17AA group), or Elental^® (Elental^® group).

RESULTS

The volume and weight of salivary glands was higher in 17AA and Elental^® groups compared to 5-FU group. The number of mucous glands was higher, whereas the number of damaged granular ductal epithelial cells was lower in the salivary glands of all groups except the 5-FU group. Salivation was also decreased in the 5-FU group compared to the other groups.

CONCLUSION

Amino acids could be the most effective components of Elental^® for protecting mouse salivary glands from 5-FU-induced atrophic changes, and might be useful in the treatment of oral mucositis in cancer patients.

Preventing heart failure: a position paper of the Heart Failure Association in collaboration with the European Association of Preventive Cardiology

The heart failure epidemic is growing and its prevention, in order to reduce associated hospital readmission rates and its clinical and economic burden, is a key issue in modern cardiovascular medicine. The present position paper aims to provide practical evidence-based information to support the implementation of effective preventive measures. After reviewing the most common risk factors, an overview of the population attributable risks in different continents is presented, to identify potentially effective opportunities for prevention and to inform preventive strategies. Finally, potential interventions that have been proposed and have been shown to be effective in preventing heart failure are listed.