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

Scent of relief: Mastic resin scent recovers salivation in chronic dry mouth patients

BACKGROUND

Olfactory stimulation with mastic resin, derived from the Pistacia lentiscus tree, demonstrated a bona fide sialagogic effect in healthy volunteers [1]. Its main volatile compound, α-pinene, also showed this effect. The current study aimed to validate the effect of mastic resin volatiles in chronic dry mouth patients with confirmed decreased saliva secretion.

METHODS

41 chronic dry mouth patients with decreased unstimulated saliva secretion (<0.25 mL/min) were exposed to mastic resin volatiles as part of the diagnostic routine at the Saliva Clinic of Academic Centre for Dentistry Amsterdam. During their visit, dry-mouth questionnaires were conducted and samples of unstimulated whole saliva, chew-stimulated saliva, acid-stimulated saliva and mastic resin stimulated saliva were collected. Saliva flow rate, spinnbarkeit, pH, ion composition, MUC5B and MUC7 levels in all samples were analyzed.

RESULTS

Salivary flow rates increased by all stimuli when compared to the baseline unstimulated saliva (P<0.001). During olfactory mastic resin stimulation, the salivary spinnbarkeit (P<0.001) and sodium concentration (P<0.01) were increased compared to unstimulated saliva. MUC5B and MUC7 levels were increased during olfactory mastic resin stimulation compared to chew-stimulated saliva (P=0.016 and P<0.001, respectively). Spinnbarkeit correlated positively with MUC5B (R=0.399, P=0.002) and MUC7 levels (R=0.375, P=0.004). Results of dry-mouth questionnaires indicated reduced posterior palate dryness shortly after olfactory mastic resin stimulation (P=0.04).

CONCLUSIONS

Olfactory mastic resin stimulation increased mucous saliva secretion and reduced posterior palate dryness in a group of chronic dry mouth patients. These findings, validated in patients, underscore mastic resin scent as a beneficial and non-invasive sialagogic treatment for clinical applications.

On the rheological and sensory properties of a novel natural salivary substitute

The prevalence of xerostomia, the sensation of dry mouth, is estimated at 20 % in the general population and up to 50 % in older adults. Saliva plays different roles during bolus formation: lubrication, mixing, coating, hydration, dissolution, and comminution of food particles. This study proposes and tests artificial saliva formulations mimicking human saliva rheological and sensory perceptions. Shear and extensional rheology were assessed to select the type of formulation closest to saliva rheological characteristics. After evaluating three alternative sources, an extract simulating saliva rheology was produced from flax seeds. Friction coefficient and rheological properties, such as flow curves, relaxation times, and Trouton ratios, were compared favorably with human saliva. The sensory evaluation demonstrated that flaxseed extracts induce perceived mouth hydration, slipperiness, and adhesion exceeding that of human saliva. The flaxseed extract proposed in this can i) be used to study in vitro food oral processing and ii) pave the way to novel natural salivary substitutes to alleviate the symptoms of xerostomia.

Tolerability of sublingual versus vestibular allergy immunotherapy tablet administration: A randomized pilot study

BACKGROUND

Local application site reactions are common with sublingual allergy immunotherapy (AIT)-tablets for the treatment of allergic rhinitis/conjunctivitis (AR/C) and occasionally lead to treatment discontinuation. Because of the lower mast cell density in the vestibular mucosa than the sublingual area, vestibular AIT-tablet administration may result in fewer adverse events (AEs). This pilot study evaluated the tolerability of the vestibular administration route of AIT-tablets compared with the sublingual route in adult subjects with AR/C.

METHODS

Adults (n = 164) aged 18-65 years with AR/C treated with daily birch pollen, grass pollen, ragweed pollen or house dust mite AIT in tablet form were randomized 1:1 to vestibular or sublingual administration for 28 days, followed by 28 days of sublingual administration only. The primary endpoint was the severity (mild, moderate, severe) of local treatment-related adverse events (TRAEs) during the first 28 days of treatment.

RESULTS

During the first 28 days, the percentage of subjects in the vestibular and sublingual groups reporting mild TRAEs were 55.6% versus 50.6%, respectively; moderate TRAEs were 27.2% versus 30.1%; and severe TRAEs were 12.3% versus 6.0% (p = .16). In the vestibular group, 95.1% of the subjects experienced at least one TRAE during the first period versus 81.9% in the sublingual group (p = .01) and discontinuation rates due to AEs were higher (12.3% vs. 3.6%).

CONCLUSION

The frequencies of subjects experiencing severe TRAEs, at least one TRAE, and discontinuations due to AEs at the initiation of AIT-tablets were numerically higher with vestibular administration than sublingual administration. Sublingual administration should remain the standard of care for subjects treated with AIT-tablets for AR/C.

Development of New Models of Oral Mucosa to Investigate the Impact of the Structure of Transmembrane Mucin-1 on the Mucosal Pellicle Formation and Its Physicochemical Properties

The mucosal pellicle (MP) is a biological film protecting the oral mucosa. It is composed of bounded salivary proteins and transmembrane mucin MUC1 expressed by oral epithelial cells. Previous research indicates that MUC1 expression enhances the binding of the main salivary protein forming the MP, MUC5B. This study investigated the influence of MUC1 structure on MP formation. A TR146 cell line, which does not express MUC1 natively, was stably transfected with genes coding for three MUC1 isoforms differing in the structure of the two main extracellular domains: the VNTR domain, exhibiting a variable number of tandem repeats, and the SEA domain, maintaining the two bound subunits of MUC1. Semi-quantification of MUC1 using dot blot chemiluminescence showed comparable expression levels in all transfected cell lines. Semi-quantification of MUC5B by immunostaining after incubation with saliva revealed that MUC1 expression significantly increased MUC5B adsorption. Neither the VNTR domain nor the SEA domain was influenced MUC5B anchoring, suggesting the key role of the MUC1 N-terminal domain. AFM-IR nanospectroscopy revealed discernible shifts indicative of changes in the chemical properties at the cell surface due to the expression of the MUC1 isoform. Furthermore, the observed chemical shifts suggest the involvement of hydrophobic effects in the interaction between MUC1 and salivary proteins.

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.

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.