Abstract
Background: Results of studies that address the influence of stress on salivary flow rate and composition are controversial. The aim of this study was to reveal the influence of stress vulnerability and different phases of stress reactivity on the unstimulated and stimulated salivary flow rate. We examined that acute mental stress does not change the salivary flow rate. In addition, we also examined the salivary cortisol and protein level in relation to acute mental stress stimuli. Methods: Saliva of male subjects was collected for five minutes before, immediately, 10, 30 and 120 min after toothbrushing. Before toothbrushing, the subjects were exposed to acute stress in the form of a 2 min public speech. Salivary flow rate and total protein was measured. The physiological stress marker cortisol was analyzed using enzyme-linked immunosorbent assay. To determine the subjects' psychological stress reaction, the State-Trait-Anxiety Inventory State questionnaire (STAI) data were obtained. The subjects were divided into stress subgroup (S1) (psychological reactivity), stress subgroup (S2) (psychological and physiological reactivity) and a control group. The area under the curve for salivarycortisol concentration and STAI-State scores were calculated. All data underwent statistical analysis using one-way analysis of variance. Results: Immediately after stress exposure, all participants exhibited a psychological stress reaction. Stress exposure did not change the salivary flow rate. Only 69% of the subjects continued to display a physiological stress reaction 20 minutes after the public talk. There was no significant change in the salivary flow rate during the psychological and the physiological stress reaction phases relative to the baseline. Conclusions: Acute stress has no impact on the salivary flow rate; however, there may be other responses through salivary proteins that are increased with the acute stress stimuli. Future studies are needed to examine specific proteins and their possible roles in acute stress responses.
Highlights
The salivary flow rate influences the chemical environment [1], the demineralization/remineralization process [2] and it provides a cleaning effect for salivary clearance in the oral cavity [3,4,5]
State questionnaire (STAI)-State scores were significantly increased across the T0, T1, T2, T3, T4 and T5 collection points in both stress subgroups (S1 and S2) compared with the control group (ANOVA group interaction effect for T0: F = 9.73; p,0.001; df = 2; T1: F = 22.22; p,0.001; df = 2; T2: F = 11.57; p,0.001; df = 2; T3: F = 10.27; p,0.001; df = 2; T4: F = 8.60; p = 0.001; df = 2; T5: F = 5.797; p = 0.006; df = 2) Fig. 2 shows the increased STAI values even 120 minutes after stress exposure
The ANOVA group differentiation between control, S1 and S2 groups revealed no group differences (F = 2.01; p = 0.142 ANOVA group interaction).The physiological stress reaction returned to the baseline cortisol level two hours after stress exposure while psychological stress reaction remained significantly elevated for up to two hours after stress exposure (STAI-State score: T0: C: 30.5663.82; S1: 42.90612.79; S2: 41.1868.23; F = 9.73; p,0.001; df = 2 and T5: C: 30.2563.62; S1: 32.1066.54; S2: 37.3268.07; F = 5.79; p = 0.006; df = 2; ANOVA group interaction)
Summary
The salivary flow rate influences the chemical environment [1], the demineralization/remineralization process [2] and it provides a cleaning effect for salivary clearance in the oral cavity [3,4,5]. The salivary flow rate is used to aid in the diagnosis of oral and systemic diseases [6] For these purposes, it is important to understand the different aspects of saliva secretion in healthy people, including its kinetics and the influencing factors. A number of studies have focused on the evaluation of the salivary secretion in healthy people during stress responses to acute mental stress [2,12,13]. We examined the salivary cortisol and protein level in relation to acute mental stress stimuli. There was no significant change in the salivary flow rate during the psychological and the physiological stress reaction phases relative to the baseline. Future studies are needed to examine specific proteins and their possible roles in acute stress responses
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