Effects of academic stress on the levels of oral volatile sulfur compounds, halitosis-related bacteria and stress biomarkers of healthy female undergraduate students

Abstract

To investigate whether academic stress changes the salivary microbiota and its relationship with salivary parameters, evaluating the effects on the production of volatile sulfur compounds (VSCs) in healthy women. Fifty-five women who were enrolled in a four-year Dentistry course were assessed for academic stress by the questionnaire Maslach Burnout Inventory—Student Survey and were then classified into ‘Not Stressed’ and ‘Stressed’ groups. Cortisol and alpha-amylase (AA) were measured as physiological stress biomarkers. Oral Chroma™ gas chromatograph was used to measure concentrations of hydrogen sulfide (H2S), methyl mercaptan and dimethyl sulfide. Salivary proteins were evaluated by western blot. Quantitative polymerase chain reaction was used to identify the salivary amounts of halitosis-associated bacteria. The ‘Stressed’ volunteers showed higher levels of H2S, AA, Fusobacterium nucleatum and total bacteria, compared to the ‘Not Stressed’ individuals (p < 0.05; Mann–Whitney test). Salivary proteins showed no differences between groups (p > 0.05; Mann–Whitney test). Academic stress was positively correlated with H2S, total bacteria and F. nucleatum counts, while F. nucleatum was positively correlated with AA. H2S showed positive correlations with AA and Solobacterium moorei (p < 0.05; Spearman correlation). Beta-defensin (BD) presented negative correlations with H2S and S. moorei (p < 0.05; Spearman correlation). Academic stress increased salivary F. nucleatum and total bacteria, as well as AA activity. The protein BD showed important correlations with bacteria and VSC. These changes appeared to be accountable for increased H2S production in the stressed women.

The Role of the Oral Microbiome in the Development of Diseases

“…Moreover, poor oral hygiene, bacterial coating of the tongue and periodontal disorders such as gingivitis, periodontitis and caries can contribute to halitosis [ 53 ]. Malodour can also be affected by dietary habits, such as smoking, alcohol consumption, obesity, diabetes, stress and advanced age [ 54 , 55 , 56 ]. In addition, risk factors such as age and tooth decay can also lead to malodour in children [ 57 ], but it is difficult to distinguish between oral bacteria that cause odour in adolescents.…”

More Than Just a Periodontal Pathogen –the Research Progress on Fusobacterium nucleatum

“…Bernardi et al (2019) revealed that the dorsal tongue biofilm of patients with halitosis had a significantly higher proportion of F. nucleatum and Streptococcus. In addition, in recent years, studies have revealed that psychological stress and anxiety can increase the discharge of VSCs in the oral cavity, which may be correlated with F. nucleatum (Nani et al, 2017;De Lima et al, 2020).…”

The Role of Oral Microbiota in Intra-Oral Halitosis

“…The factors that increase the likelihood of halitosis include periodontal diseases, dry mouth, smoking, alcohol consumption, dietary habits, diabetes, and obesity. Halitosis can also be affected by the general hygiene of the body (i.e., dehydration, starvation, and high physical exertion), advanced age, bleeding gums, decreased brushing frequency, but also by stress [3,[13][14][15][16]. Produced during stress, catecholamines and cortisol increased hydrogen sulfide production by sub-gingival anaerobic bacteria [17].…”