Salivary aquaporin-3 as a screening biomarker for xerostomia in patients with periodontal disease and the effects of xerostomia on oral health-related quality of life.

Xerostomia is a subjective condition of dryness of the oral cavity that may lead to several oral problems deteriorating oral health-related quality of life. This study aimed to (1) determine the prevalence of xerostomia, (2) compare the general health status, unstimulated salivary flow rate, and oral health-related quality of life in xerostomics and non-xerostomics, and (3) investigate the potential of salivary aquaporin-3 (AQP-3) as a screening biomarker for xerostomia in patients with periodontal disease. Demographics and systemic health data were collected from 109 healthy participants, 20 to 55 years old, with Community Periodontal Index (CPI) score ≥ 3. For subjective assessment of xerostomia, Shortened Xerostomia Inventory (SXI) was used. For objective assessment of xerostomia, unstimulated salivary flow rate was measured. Shortened Oral Health Impact Profile (S-OHIP) was utilized for oral health-related quality of life assessment. The collected saliva samples were processed and stored at -80°C. Quantification of salivary AQP-3 protein was done with enzyme-linked immunosorbent assay. Xerostomia was reported in 78% of the subjects based on SXI score. Median concentration of AQP-3 was significantly higher in xerostomics compared to non-xerostomics, p = 0.001. Moreover, oral health-related quality of life was significantly poor in xerostomics compared to non-xerostomics, p = 0.002. Furthermore, there were significant correlations between AQP-3 and SXI (r = 0.21, p = 0.025), AQP-3 and S-OHIP (r = 0.2, p = 0.042), S-OHIP and SXI (r = 0.37, p < 0.001), unstimulated salivary flow rate and random blood glucose level (r = 0.32, p = 0.001), and body mass index and mean arterial pressure (r = 0.44, p < 0.001). Regression analysis showed that body mass index, CPI score 3, and salivary AQP-3 were suitable predictors for presence of xerostomia. AQP-3 could be a potential screening biomarker for xerostomia in patients with periodontal disease for its early identification may help improve oral health-related quality of life of the individuals.

Effects of olfactory and gustatory stimuli on neural excitability for swallowing.

This project evaluated the effects of olfactory and gustatory stimuli on the amplitude and latency of motor-evoked potentials (MEPs) from the submental muscles when evoked by transcranial magnetic stimulation (TMS). Sixteen healthy volunteers (8 males; age range 19-43) participated in the study. Lemon concentrate at 100% and diluted in water to 25% were presented separately as odor and tastant stimuli. Tap water was used as control. 15 trials of TMS-evoked MEPs triggered by volitional contraction of the submental muscles and volitional swallowing were measured at baseline, during control condition, during stimulus presentation, and immediately, 30-, 60-, and 90-min poststimulation for each of the four stimulus presentations. Experiments were repeated using the combined odor and tastant concentrations that most influenced the MEP independently. Differences in MEP amplitude measured during swallowing were seen at 30-, 60-, and 90-min poststimulation for simultaneous olfactory and gustatory stimulation as opposed to no differences seen at any point for stimuli presented separately. This study has shown that combined odor and tastant stimulation (i.e., flavor) can increase MEP amplitude during swallowing and that this enhancement of MEP can persist for at least 90min following stimulation. As increased MEP amplitude has been associated with improved swallowing performance, a follow-up study is underway to determine the biomechanical changes produced by altered MEPs to facilitate translation of these data to clinical dysphagia management.