Stimulated whole salivary flow rate: The most appropriate technique for assessing salivary flow in Sjögren syndrome

Prediction of xerostomia in elderly based on clinical characteristics and salivary flow rate with machine learning

Xerostomia may be accompanied by changes in salivary flow rate and the incidence increases in elderly. We aimed to use machine learning algorithms, to identify significant predictors for the presence of xerostomia. This study is the first to predict xerostomia with salivary flow rate in elderly based on artificial intelligence. In a cross-sectional study, 829 patients with oral discomfort were enrolled, and six features (sex, age, unstimulated and stimulated salivary flow rates (UFR and SFR, respectively), number of systemic diseases, and medication usage) were used in four machine learning algorithms to predict the presence of xerostomia. The incidence of xerostomia increased with age. The SFR was significantly higher than the UFR, and the UFR and SFR were significantly correlated. The UFR, but not SFR, decreased with age significantly. In patients more than 60 years of age, the UFR had a significantly higher predictive accuracy for xerostomia than the SFR. Using machine learning algorithms with tenfold cross-validation, the prediction accuracy increased significantly. In particular, the prediction accuracy of the multilayer perceptron (MLP) algorithm that combined UFR and SFR data was significantly better than either UFR or SFR individually. Moreover, when sex, age, number of systemic diseases, and number of medications were added to the MLP model, the prediction accuracy increased from 56 to 68%.

Comparison of Salivary Secretion, pH, and Buffer Capacity Between COVID-19 Vaccinated and Unvaccinated Child Patients Visiting Dental Clinics of University Hospitals in Riyadh City, Saudi Arabia

Objective

This study aimed to assess and compare the salivary secretion, pH, and buffer capacity between COVID-19 vaccinated and unvaccinated child patients visiting the clinics of private university dental hospitals in Riyadh, Saudi Arabia.

Methods

This is the first comparative assessment of salivary parameters between unvaccinated and COVID-19-vaccinated child patients. The study sample comprised COVID-19 unvaccinated (n = 66) and vaccinated (n = 66) pediatric dental patients aged 4-12 years seeking dental care in clinics of private university hospitals. Paraffin-stimulated saliva was collected from unvaccinated and vaccinated study participants, and the amount of saliva secreted per minute was noted. Salivary pH and buffering capacity (by 5 mmol Hydrochloric acid titration) were measured using a benchtop digital pH meter. The data obtained were compared between unvaccinated and vaccinated participants using an independent t-test.

Results

The results showed a significantly higher salivary secretion rate in unvaccinated than vaccinated study participants (0.83 ± 0.24 mL/min vs 0.67 ± 0.24 mL/min, p = 0.001). Similarly, unvaccinated subjects compared to vaccinated subjects exhibited a significantly higher pH (7.33 ± 0.39 vs 7.04 ± 0.46, p < 0.001) and buffering capacity (6.31 ± 1.55 vs 5.40 ± 1.22, p < 0.001). Moreover, unvaccinated females demonstrated a significantly higher salivary secretion (0.87 ± 0.23 vs 0.71 ± 0.25, t = 2.627, p = 0.011) and buffering capacity 6.19 ± 1.52 vs 5.34 ± 1.25, t = 2.404, p = 0.019) than vaccinated females. Similarly, unvaccinated male exhibited significantly higher salivary secretion (0.80 ± 0.25 vs 0.64 ± 0.23, t = 2.670, p = 0.009), salivary pH (7.39 ± 0.45 vs 6.94 ± 0.41, t=4.309, p<0.001) and buffering capacity (6.42 ± 1.60 vs 5.45 ± 1.21, t = 2.875, p = 0.005) than the vaccinated male subjects.

Conclusion

The vaccinated subjects showed a significantly lower mean salivary secretion, pH, and buffering capacity than unvaccinated participants. Hence, COVID-19 vaccination is likely to affect salivary parameters among pediatric patients.

Hyposalivation but not Sjögren's syndrome associated with microbial dysbiosis in women

Background

Saliva modulates the environment of the oral biofilm through pH buffer, microbial attachment to host surfaces, and nutritional source. The ecology of stress occurs when a physical factor adversely impacts an ecosystem or its biotic components. Therefore, reduced salivary flow can affect oral-host balance. The leading causes of hyposalivation include disease-associated Sjögren's syndrome (SS) and menopausal women as aging-associated. However, little is known about the oral microbiome integrated with sex hormones in hyposalivation. This study aimed to characterize the hyposalivation microbiome caused by aging or disease affecting the salivary glands in women.

Methods

We included 50 women older than 40 years of age in any menopausal phase. We collected stimulated saliva from 25 women diagnosed with SS (SS) and 25 without SS (non-SS). The bacterial profile of the patients was obtained by 16S rRNA sequencing. Bioinformatics analysis used machine learning to analyze the cohort's signs, symptoms, and bacterial profile. Salivary estradiol as a sex hormone variation level was determined.

Results

We obtained that 79% of the SS group, and 52% of the non-SS group had hyposalivation. We found a negatively correlated Prevotella-age and Rothia-estradiol in the SS group. Highlight, we found that the cause of the hyposalivation in the study did not explain differences in microbial diversity comparing non-SS and SS groups. Therefore, microbial communities found in hyposalivation but not related to systemic conditions suggest that changes in the oral environment might underpin host-microbial balance.

Conclusion

The salivary microbiome was similar in women with and without SS. However, hyposalivation showed two distinctive clusters associated with the bacterial population profiles. Our study suggests that local ecological disturbances could drive the change in the microbiome.

Diagnostic value of ultrasound evaluation of major salivary glands for Sjögren's syndrome based on the novel OMERACT scoring system

OBJECTIVE

The novel Outcome Measures in Rheumatology Clinical Trials (OMERACT) scoring system was used to evaluate the diagnostic effectiveness of major salivary gland ultrasonography (SGUS) for Sjögren's syndrome (SS).

MATERIALS AND METHODS

SGUS was performed on the parotid glands (PGs) and submandibular glands of 242 patients (145 patients with SS and 97 patients without SS) using the OMERACT scoring system (grade 0-3). We also evaluated the association of SGUS scores with unstimulated whole salivary flow rate (UWSF), stimulated whole salivary flow rate (SWSF), and labial salivary gland biopsy (LSGB) results.

RESULTS

The SGUS scores were significantly higher for the SS group than for the non-SS group (p < 0.001). Using a cutoff value of 8 for the total score yielded the highest sensitivity (76%), specificity (90%), and area under the receiver operating characteristic curve (AUC, 0.828). The correlation between SGUS scores and salivary gland function was moderate to good. A cutoff value of 10 for the total score was more effective in predicting SWSF outcomes than UWSF outcomes (sensitivity: 73% > 58%, specificity: 98% > 87%, and AUC: 0.856 > 0.723). The association of OMERACT scores with LSGB results was fair to moderate. Among 61 anti-SSA-negative patients, 17 had positive PG scores (including ten SS and seven non-SS patients), and 44 had negative PG scores (including 37 non-SS and seven SS patients).

CONCLUSION

The OMERACT scoring system had good sensitivity and excellent specificity, demonstrating excellent diagnostic potential for SS and efficacy in assessing salivary gland function. Negative SGUS results may help reduce unnecessary biopsies in anti-SSA-negative patients.

Usefulness of implementing the OHIP-14 questionnaire to assess the impact of xerostomia and hyposalivation on quality of life in patients with primary Sjögren's syndrome

BACKGROUND

The aim of this study is to analyze if the results of the Oral Health Impact Profile-14 questionnaire (OHIP-14) in patients with primary Sjögren's syndrome (pSS) are correlated with salivary flow and level of xerostomia.

METHODS

This observational cross-sectional study was conducted in 61 patients (60 women, one man, mean age 57.64 [13.52]) diagnosed of pSS according to the American-European Criteria (2002). After recording demographic, medical and dental data (decayed-missing-filled teeth index [DMFT]), unstimulated (UWS) and stimulated (SWS) salivary flows were collected. Subsequently, UWS flow was categorized into two groups (<0.1 ml/min and ≥0.1 ml/min) and SWS into three groups (<0.1 ml/min, 0.1-0.7 ml/min and >0.7 ml/min). Patients also filled out a visual analog scale (VAS) for xerostomia and OHIP-14 for self-reported quality of life (QoL).

RESULTS

Data showed positive and significant correlation between OHIP-14 and xerostomia, based on VAS results (r = 0.52; p = 0.001). Furthermore, there was a negative correlation between UWS and OHIP-14 scores (r = -0.34; p = 0.006) and VAS for xerostomia (r = -0.22; p = 0.09). No significant correlation was found between SWS and OHIP-14 or VAS neither between DMFT and OHIP-14. When assessing the level of QoL by the UWS and SWS flow categories a significant association was found for UWS (p = 0.001) but not for SWS (p = 0.11). The OHIP-14 values were higher in the groups with lower salivary flow. The multiple linear regression to predict OHIP-14 only selected VAS for xerostomia as a statistically significant predictor.

CONCLUSIONS

Increased level of xerostomia and reduced UWS flow decrease oral health-related QoL in patients with pSS.

Diagnosis, Prevention, and Treatment of Radiotherapy-Induced Xerostomia: A Review

In patients with head and neck cancer, irradiation (IR)-sensitive salivary gland (SG) tissue is highly prone to damage during radiotherapy (RT). This leads to SG hypofunction and xerostomia. Xerostomia is defined as the subjective complaint of dry mouth, which can cause other symptoms and adversely affect the quality of life. In recent years, diagnostic techniques have constantly improved with the emergence of more reliable and valid questionnaires as well as more accurate equipment for saliva flow rate measurement and imaging methods. Preventive measures such as the antioxidant MitoTEMPO, botulinum toxin (BoNT), and growth factors have been successfully applied in animal experiments, resulting in positive outcomes. Interventions, such as the new delivery methods of pilocarpine, edible saliva substitutes, acupuncture and electrical stimulation, gene transfer, and stem cell transplantation, have shown potential to alleviate or restore xerostomia in patients. The review summarizes the existing and new diagnostic methods for xerostomia, along with current and potential strategies for reducing IR-induced damage to SG function. We also aim to provide guidance on the advantages and disadvantages of the diagnostic methods. Additionally, most prevention and treatment methods remain in the stage of animal experiments, suggesting a need for further clinical research, among which we believe that antioxidants, gene transfer, and stem cell transplantation have broad prospects.

[Effects of acid stimulation on saliva flow rate and compositions of human parotid and submandibular glands]

OBJECTIVE

To investigate the effect of acid stimulation on salivary flow rate and compositions of human parotid and submandibular glands, so as to provide basis for comprehensive evaluation of salivary gland function in both health and disease status.

METHODS

In the study, 210 healthy participants' whole saliva samples were collected under passive drooling, and their parotid gland and submandibular gland secretions were collected by negative pressure suction. 2% citric acid was dropped on the tip of tongue every 1 min for acid stimulation for a total of 5 times to collect stimulated whole saliva, parotid and submandibular gland saliva. The collected saliva was weighed and saliva flow rate was calculated. The K⁺, Na⁺, Cl^-, Ca²⁺, total protein, total phosphorus and α-amylase in saliva samples were detected by biochemical analyzer, and the changing features of flow rate and compositions of different kinds of saliva were compared and analyzed.

RESULTS

After acid stimulation, saliva flow rate significantly increased. The increase proportion of parotid gland saliva (10.7 folds) was much higher than that of submandibular gland saliva (2.9 folds). The concentrations of Na⁺, Cl^-, Ca²⁺, total protein and α-amylase in parotid gland saliva increased significantly (P < 0.05), but there was no significant difference in total phosphorus and K⁺ (P=0.89, P=0.34). The concentration of Na⁺ and Ca²⁺ in saliva of submandibular gland increased significantly(P < 0.05), the concentration of total phosphorus decreased significantly(P < 0.05), and the concentration of Cl^- increased, but the difference was not significant(P=0.068). There was no significant difference in total protein, K⁺ and α-amylase (P=0.85, P=0.07, P=0.95). The compound secretion rate of total phosphorus in saliva of submandibular gland remained unchanged(P=0.066), while the secretion rate of K⁺, Na⁺, Cl^-, Ca²⁺, total protein and α-amylase significantly increased(P < 0.01). The compound secretion rate of K⁺, Na⁺, Cl^-, Ca²⁺, total protein and total phosphorus and α-amylase in parotid gland saliva increased(P < 0.01). The concentrations of Na⁺, Cl^-, K⁺, total phosphorus, total protein and α-amylase in parotid were higher than those in submandibular gland (P < 0.01), and the concentration of Ca²⁺ in submandibular gland saliva was significantly higher than that in parotid (P < 0.001).

CONCLUSION

The response of parotid to acid stimulation is stronger, and the secretion of submandibular gland is more stable. Acid stimulation significantly influences the concentrations of electrolytes in saliva, and the composited secretion rate is an evaluation index to reflect both flow rate and composition concentration of saliva. The parotid gland plays an important role in the secretion of total protein, total phosphorus and α-amylase in saliva, and the submandibular gland is the main source of Ca²⁺ in saliva.

Salivary Biomarkers in Patients with Sjögren's Syndrome-A Systematic Review

Sjögren's syndrome (SS) is a chronic autoimmune disease characterized by dry mouth and dry eyes, with lymphocytic infiltration of the exocrine glands. Saliva is becoming a useful tool to determine the clinical and pathological characteristics of SS because the collection method is easy and non-invasive. Since 1900, salivary proteomic analysis has been performed continuously using a variety of optimized analytical methods. Many studies have identified distinct characteristics of salivary proteins in patients with primary SS, and the changes were related to chronic inflammation and overproduction of immunoglobulins or downregulated secretory function. Several proteomic studies using whole or parotid saliva have evaluated whether several salivary proteins can be used to discriminate SS, including salivary β2-microglobulin, calprotectin, carbonic anhydrase VI, neutrophil gelatinase-associated lipocalin, sialic acid-binding immunoglobulin-like lectin-5, and tripartite motif-containing protein 29. In addition, salivary proinflammatory cytokine levels have been reported to be increased in patients with SS. Although these candidate salivary proteins have exhibited considerable differences in patients with SS, more data are needed to confirm their role as biomarkers. Moreover, the identification of salivary characteristics that can accurately reflect disease activity, predict treatment response and prognosis, and diagnose SS is anticipated.