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. 2026 Aug 20;26:1891. doi: 10.1186/s12903-026-09460-7

Association between perceived stress and self-reported halitosis among university students: the mediating role of xerostomia, a cross-sectional study

Semra Eser 1,✉, Özlem Bulantekin Düzalan 2
PMCID: PMC13632209  PMID: 42823683

Abstract

Background

Halitosis is a common oral health concern with notable psychosocial consequences. Although psychological stress has been linked to various oral conditions, the specific mechanism through which perceived stress contributes to self-reported halitosis remains unclear. This study aimed to determine the prevalence of self-reported halitosis among university students and to evaluate the associations between perceived stress levels, oral hygiene behaviors, xerostomia, and self-reported halitosis, with a particular focus on the potential mediating role of xerostomia.

Methods

A cross-sectional study was conducted among 400 students from Çankırı Karatekin University’s Faculty of Dentistry and Faculty of Health Sciences, Department of Nursing, using a non probability voluntary response sampling method. Data were collected via a self administered online questionnaire (Google Forms) that included items on demographic characteristics, oral hygiene behaviors, and single item questions on xerostomia and self-reported halitosis. Perceived stress was assessed using the validated Turkish version of the Perceived Stress Scale (PSS-10). Associations were examined using chi square tests and binary logistic regression. The mediating role of xerostomia in the relationship between perceived stress and self-reported halitosis was evaluated through mediation analysis.

Results

The prevalence of self-reported daytime halitosis was 18.5%, and 67.8% of participants reported xerostomia. Perceived stress was significantly associated with both self-reported halitosis and xerostomia. Mediation analysis revealed that xerostomia statistically mediated the association between perceived stress and self-reported halitosis (indirect effect = 0.653, 95% bootstrap CI [0.184, 1.122]). Xerostomia was a significant predictor of halitosis (OR = 3.249, 95% CI: 1.647–6.408, p = 0.001). Additionally, self-reported halitosis was significantly associated with brushing frequency, gingival bleeding, and smoking status. Statistically significant differences in perceived stress levels were observed based on gender and faculty of enrollment.

Conclusions

Perceived stress is associated with self-reported halitosis among university students, and this association is statistically mediated by xerostomia. These findings suggest that xerostomia may represent a potential mechanism linking perceived stress and self-reported halitosis. Future studies employing larger samples and objective clinical measurements, such as sialometry and volatile sulfur compound analysis, are needed to confirm these associations.

Supplementary Information

The online version contains supplementary material available at https://doi.org/10.1186/s12903-026-09460-7.

Keywords: Self-reported halitosis, Perceived stress, Xerostomia, Oral hygiene behaviors, Mediation analysis, University students, PSS-10

Background

Halitosis is commonly described as an unpleasant odor from the mouth, primarily caused by volatile sulfur compounds produced through microbial degradation of peptides in the oral cavity [1, 2]. Morning breath and odor associated with aromatic foods are considered physiological and transient, whereas persistent oral malodor is classified as pathological halitosis and may be linked to both intraoral and extraoral causes [3]. Common intraoral factors include tongue coating, poor oral hygiene, periodontal diseases, dry mouth, and oral candidiasis [2, 4].

Stress refers to the pressure experienced when a person perceives that environmental demands exceed his or her capacity to cope [5]. University students are exposed to stress related to examinations, heavy workload, and academic competition [6, 7]. Stress coping may involve avoidance or reward seeking behaviors [8], and smoking is often motivated by pleasure and stress relief [9]. Stress increases susceptibility to periodontal disease [10–12], and stress-related smoking may further compromise periodontal health [13, 14]. Oral hygiene habits may also deteriorate under stress, worsening periodontal status [15]. As a result, stress-related changes in oral hygiene and periodontal condition may contribute to the development of halitosis [2, 16].

Salivary output may temporarily decrease during periods of stress, nervousness, or anxiety [17]. Under stress, this reduction appears to occur primarily through central suppression of parasympathetic reflex activity rather than through direct sympathetic inhibition, as sympathetic nerve activity contributes only slightly to overall salivary volüme [18]. The sympathetic response instead mainly alters the protein composition of saliva as part of an adaptive mechanism [18]. Xerostomia, defined as the subjective sensation of oral dryness, may or may not be accompanied by a measurable reduction in salivary flow [19, 20]. Changes in salivary protein content have been reported to elicit a perception of dry mouth even when flow rate remains unchanged [21, 22]. It has been reported that increased saliva viscosity, or increased plaque accumulation due to reduced salivary flow and buffering capacity, can contribute to the development of halitosis [23], and that adequate fluid intake reduces the likelihood of halitosis [24]. A recent study among young adults found that those reporting halitosis and higher stress levels also reported more severe xerostomia [25]. Although these findings point to an association between perceived stress, xerostomia, and halitosis [26–30], whether xerostomia acts as a mediating factor in the relationship between perceived stress and self-reported halitosis has not been directly addressed.

The aim of this study was to determine the prevalence of self-reported halitosis among students enrolled in the Faculty of Dentistry and the Faculty of Health Sciences, Department of Nursing, at a Turkish university, and to evaluate the associations between perceived stress, oral hygiene behaviors, xerostomia, and self-reported halitosis. Specifically, we sought to test whether xerostomia mediates the association between perceived stress and self-reported halitosis.

Methods

Study design and participants

This cross-sectional study was conducted during the final examination period in June 2025 among students enrolled at the Faculty of Dentistry and the Department of Nursing, Faculty of Health Sciences, at Çankırı Karatekin University. All registered students in both faculties were invited to participate (N = 829; Nursing: 325 female and 190 male; Dentistry: 186 female and 128 male). Participation was on a voluntary basis, constituting a non-probability voluntary response sampling method. A self administered online questionnaire was distributed to all students via Google Forms, and 400 students completed the survey, yielding a response rate of 48.3%.

The required sample size was determined a priori using G*Power software (version 3.1). Based on a chi-square goodness of fit test with an effect size of w = 0.20, an alpha level of 0.05, one degree of freedom, and a target power of 0.97, the minimum required sample size was calculated as 369 participants (actual power = 0.970). The final sample of 400 exceeded this threshold. Perceived stress was defined as the independent variable and self-reported halitosis as the dependent variable.

The study protocol was approved by the Health Sciences Ethics Committee of Çankırı Karatekin University (Meeting No: 18) and was carried out in accordance with the Declaration of Helsinki. All participants provided informed consent electronically before completing the questionnaire.

Data collection

Perceived stress was measured using the Perceived Stress Scale (PSS-10) [31], which evaluates the degree to which respondents have found their lives unpredictable, uncontrollable, and overloading during the past month. Each item is rated on a 5-point Likert scale (0 = never, 4 = very often). The Turkish adaptation of the PSS-10 has demonstrated acceptable reliability and validity [32, 33].

Demographic characteristics, oral hygiene behaviors, xerostomia, and self-reported halitosis were assessed using a questionnaire adapted from previously published surveys [34–39], with additional items developed for the purposes of this study. The full questionnaire is provided as Additional file 1. Xerostomia was assessed using a single self-report question (Do you experience dry mouth? ) with three response options (never / sometimes / often). Participants responding ‘sometimes’ or ‘often’ were classified as having xerostomia, an approach consistent with previous epidemiological studies [38, 39]. In this questionnaire based study without clinical measurements, self-reported halitosis was assessed using two questions: ‘Do you feel that you have bad breath in the morning?’ and ‘Do you feel that you have bad breath during the day?’, each with four response options (never / rarely / occasionally / always). Since morning breath is generally regarded as physiological and transient [3, 40], only the daytime question was used to define the presence of self-reported halitosis. Following the methodology of a previous study [30], participants responding ‘occasionally’ or ‘always’ were classified as having self-reported halitosis, while those responding ‘never’ or ‘rarely’ were classified as halitosis free.

Statistical analysis

Only fully completed questionnaires were included in the analysis (n = 400; no missing data). The internal consistency of the PSS-10 was assessed using Cronbach’s alpha. Normality of continuous variables was evaluated with the Shapiro Wilk test.

Group comparisons were performed using independent samples t-tests or Mann Whitney U tests for two groups, and one way ANOVA or Kruskal Wallis H tests (with Dunn Bonferroni post hoc correction) for more than two groups, depending on data distribution. Categorical variables were analyzed using Pearson’s chi square test or Fisher’s exact test where appropriate.

Binary logistic regression was used to identify independent predictors of self-reported halitosis. To examine whether xerostomia mediates the association between perceived stress and self-reported halitosis, a mediation analysis was conducted using the PROCESS macro for SPSS [41], with 5,000 bootstrap resamples to estimate 95% bias corrected confidence intervals for the indirect effect. Mediation was considered present when the bootstrap confidence interval for the indirect effect did not include zero. The significance level was set at p < 0.05 for all analyses. All statistical procedures were carried out using IBM SPSS Statistics version 26.0 (IBM Corp., Armonk, NY, USA).

Results

Of the 829 students invited, 400 completed the questionnaire (response rate: 48.3%). The gender distribution of the study sample did not differ significantly from the source population (χ² = 2.70, p = 0.10). The PSS-10 demonstrated high internal consistency (Cronbach’s α = 0.831), and the mean perceived stress score was 2.23 ± 0.56.

Morning halitosis was reported by 27.25% of participants (n = 109). As morning breath is generally considered physiological and transient [3, 40], only daytime halitosis was used to define self-reported halitosis in the analyses. The prevalence of self-reported daytime halitosis was 18.5% (n = 74).

Perceived stress by gender and faculty

Female students reported significantly higher perceived stress scores than male students, and dentistry students scored higher than nursing students (Tables 1 and 2; p < 0.05). No significant differences were found in halitosis prevalence by gender, faculty, or academic term (p > 0.05). The prevalence of xerostomia was also similar between genders (68.7% (n = 180) in females vs. 65.9% (n = 91) in males; p = 0.575).

Table 1.

Comparison of perceived stress scores by gender

Female Male Test Statistics p d
Perceived Stress Score 23.25 ± 5.32 20.38 ± 5.51 -5.145 0.001† 0.53
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Numerical variables were given as mean±standard deviation. ‡: t test, †Mann-Whitney U test in independent samples

Table 2.

Comparison of perceived stress scores by faculty

Faculty of Dentistry Faculty of Nursing Test Statistics p d
Perceived Stress Score 22.92 ± 5.96 20.99 ± 4.42 -3.075 0.002† 0.32
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Numerical variables were given as mean±standard deviation. ‡: t test, †Mann-Whitney U test in independent samples

Oral hygiene behaviors

Dentistry students had higher brushing frequency, whereas nursing students reported more frequent use of interdental cleaning aids, tongue cleaning, and mouthwash (Table 3; p < 0.05).

Table 3.

Comparison of oral hygiene behaviors by faculty

Faculty Total Test Statistics p Cramer’s V
Faculty of Dentistry Faculty of Nursing
How often have you brushed your teeth over the last month? Less than once a day n 10a 8a 18 19.773 0.001& 0.222
% 3.8% 5.8% 4.5%
Once a day n 62a 60b 122
% 23.6% 43.8% 30.5%
Twice a day or more n 191a 69b 260
% 72.6% 50.4% 65.0%
For how long have you been brushed your teeth at each insance over the last month? Shorter than 1 min n 13 10 23 3.163 0.206&
% 4.9% 7.3% 5.8%
1–2 min n 164 93 257
% 62.4% 67.9% 64.3%
Longer than 2 min n 86 34 120
% 32.7% 24.8% 30.0%
How often have you brushed your interfaces over the last month? Never n 74a 12b 86 67.165 0.001& 0.410
% 28.1% 8.8% 21.5%
Once a day or less n 166a 68b 234
% 63.1% 49.6% 58.5%
Twice a day or more n 23a 57b 80
% 8.7% 41.6% 20.0%
How often have you cleaned your tongue over the last month? Never n 89a 33b 122 6.520 0.038& 0.128
% 33.8% 24.1% 30.5%
Less than once a day n 118a 61a 179
% 44.9% 44.5% 44.8%
Once a day or more n 56a 43b 99
% 21.3% 31.4% 24.8%
How often have you used mouthwash over the last month? Never n 155a 62b 217 9.006 0.011& 0.150
% 58.9% 45.3% 54.3%
Once a day or less n 90a 56a 146
% 34.2% 40.9% 36.5%
Twice a day or more n 18a 19b 37
% 6.8% 13.9% 9.3%
Total n 263 137 400
% 100.0% 100.0% 100.0%
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n Number of individuals, % Provided as the percentage of the column

&Chi-square analysis

ƞ Fisher exact test

Systemic diseases and medication use

No significant associations were found between systemic diseases and either halitosis or stress levels (p > 0.05). Medication use was not associated with halitosis either; however, participants who reported using medication had higher perceived stress scores than non-users (24.53 ± 4.81 vs. 22.08 ± 5.56; p < 0.05).

Xerostomia, halitosis, and associated factors

Participants who reported xerostomia had significantly higher mean stress scores than those who did not (Table 4; p < 0.05). The prevalence of xerostomia was similar between genders (68.7% in females vs. 65.9% in males; χ² = 0.315, p = 0.575). Self-reported halitosis was significantly more common among smokers, individuals who experienced gingival bleeding, and those with xerostomia (Tables 5, 6 and 7; p < 0.05). Alcohol consumption and age were not associated with halitosis. Lower brushing frequency and shorter brushing duration were also significant predictors of halitosis (Table 8; p < 0.05). Mean perceived stress scores were higher in participants who reported halitosis compared to those who did not (Table 9; p < 0.05). No significant gender difference was observed in self-reported halitosis prevalence either.

Table 4.

Correlation between xerostomia and perceived stress score

No Yes Test Statistics p d
Perceived Stress Score 21.09 ± 5.78 22.81 ± 5.36 -2.8 0.005† 0.27
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Numerical variables were given as mean±standard deviation, ‡ t test, †Mann-Whitney U test in independent samples

Table 5.

Correlation between smoking habits and halitosis

Halitosis Total Test Statistics p Cramer’s V
No Yes
Are you a smoker? Yes n 76a 27b 103 5.474 0.019& 0.117
% 73.8% 26.2% 100.0%
No n 250a 47b 297
% 84.2% 15.8% 100.0%
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n Number of individuals, % Provided as the percentage of the column, & Chi-square analysis, ƞ Fisher exact t

Table 6.

Correlation between gingival bleeding and halitosis

Halitosis Total Test Statistics p Cramer’s V
No Yes
Do you experience bleeding while brushing your teeth? No n 157a 20b 177 10.918 0.001& 0.165
% 88.7% 11.3% 100.0%
Yes n 169a 54b 223
% 75.8% 24.2% 100.0%
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n Number of individuals, % Provided as the percentage of the column, & Chi-square analysis, ƞFisher’s exact test

Table 7.

Correlation between xerostomia and halitosis

Halitosis Total Test Statistics p Cramer’s V
No Yes
Do you feel a dry mouth? No n 118a 11b 129 12.560 0.001& 0.177
% 91.5% 8.5% 100.0%
Yes n 208a 63b 271
% 76.8% 23.2% 100.0%
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n Number of individuals, % Provided as the percentage of the column. & Chi-square analysis, ƞ Fisher’s exact test

Table 8.

Comparison of oral hygiene behaviors by halitosis status

Halitosis Total Test Statistics p Cramer’s V
No Yes
What was your tooth brushing frequency over the last month? Less than once a day n 10a 8b 18 9.643 0.008& 0.155
% 55.6% 44.4% 100%
Once a day n 97a 25a 122
% 79.5% 20.5% 100%
Twice a day or more n 219a 41a 260
% 84.2% 15.8% 100%
For how long have you been brushing your teeth at each instance over the last month? Shorter than 1 min n 13a 10b 23 12.437 0.002& 0.176
% 56.5% 43.5% 100%
1–2 min n 208a 49a 257
% 80.9% 19.1% 100%
Longer than 2 min n 105a 15b 120
% 87.5% 12.5% 100%
How often have you used an interdental brush over last month? Never n 67 19 86 0.938 0.626&
% 77.9% 22.1% 100%
Once a day or less n 193 41 234
% 82.5% 17.5% 100%
Twice a day or more n 66 14 80
% 82.5% 17.5% 100%
How often have you cleaned your tongue over the last month? Never n 96 26 122 1.916 0.384&
% 78.7% 21.3% 100%
Less than once a day n 145 34 179
% 81.0% 19.0% 100%
Once a day or more n 85 14 99
% 85.9% 14.1% 100%
How often have you used mouthwash over the last month? Never n 170 47 217 3.205 0.201&
% 78.3% 21.7% 100%
Once a day or less n 125 21 146
% 85.6% 14.4% 100%
Twice a day or more n 31 6 37
% 83.8% 16.2% 100%
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n Number of individuals, % Provided as the percentage of the column. & Chi-square analysis, ƞ Fisher’s exact test

Table 9.

Correlation between perceived stress and halitosis status

No Yes Test Statistics p d
Perceived Stress Score 22.01 ± 5.81 23.36 ± 4.06 -2.521 0.012† 0.33
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Numerical variables were given as mean±standard deviation. ‡: t test, †Mann-Whitney U test in independent samples

Logistic regression and mediation analysis

To account for potential confounders, all variables that showed a significant association with halitosis in the bivariate analyses were entered into a multivariate logistic regression model (Table 10). In the univariate analysis, perceived stress showed a borderline association with halitosis (crude OR = 1.554, p = 0.050). After adjusting for all variables in the multivariate model (Table 10), brushing duration of more than two minutes (adjusted OR = 0.299, 95% CI: 0.104–0.862, p = 0.025) and gingival bleeding (adjusted OR = 2.356, 95% CI: 1.325–4.192, p = 0.004) remained significant independent predictors of self-reported halitosis. Perceived stress was no longer significant after adjustment (adjusted OR = 1.501, 95% CI: 0.922–2.444, p = 0.103).

Table 10.

Multivariate logistic regression analysis for predictors of halitosis

Variables Crude OR
(95% Cl)		 p Adjusted OR
(95% Cl)		 p
Perceived stress 1.554 (0.985–2.451) 0.050 1.501 (0.922–2.444) 0.103
Gender (Male) 1.195 (0.709–2.016) 0.504 — —
Faculty (Nursing) 1.212 (0.718–2.045) 0.472 — —
Toothbrushing frequency – Once daily 0.322 (0.115–0.901) 0.031 0.443 (0.149–1.317) 0.143
Toothbrushing frequency – ≥Twice daily 0.234 (0.087–0.628) 0.004 0.358 (0.125–1.026) 0.056
Brushing duration – 1–2 min 0.306 (0.127–0.739) 0.008 0.437 (0.170–1.127) 0.087
Brushing duration – >2 min 0.186 (0.069–0.498) 0.001 0.299 (0.104–0.862) 0.025
Smoking (No) 0.529 (0.309–0.907) 0.021 0.589 (0.334–1.039) 0.067
Gingival bleeding (Yes) 2.508 (1.437–4.379) 0.001 2.356 (1.325–4.192) 0.004
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OR Odds Ratio, CI Confidence Interval. Adjusted for all variables in the table. p < 0.05

Mediation analysis (Table 11) indicated that the association between perceived stress and self-reported halitosis was statistically mediated by xerostomia. When xerostomia was included in the model, the direct effect of stress on halitosis was no longer significant, while the indirect effect through xerostomia remained significant (indirect effect = 0.653, 95% bootstrap CI [0.184, 1.122]). These results suggest that xerostomia may act as an intermediate variable in the association between perceived stress and self-reported halitosis.

Table 11.

Mediation role of xerostomia in the relationship between perceived stress and halitosis

Model OR (95% Cl) p
Model 1 Perceived stress → Halitosis (Total Effect) 1.554 (0.985–2.451) 0.050*
Model 2 Perceived stress → Xerostomia (Path a) 1.786 (1.200–2.657) 0.004
Model 3 Xerostomia → Halitosis (Path b) 3.249 (1.647–6.408) 0.001
Model 4 Perceived stress + Xerostomia → Halitosis (Direct Effect)

Stress: 1.414 (0.882–2.267)

Xerostomia: 3.084 (1.558–6.106)

 0.150 / 0.001
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OR Odds Ratio, CI Confidence Interval. Mediation analysis was performed using PROCESS macro Model 4 (Hayes, 2018) with 5,000 bootstrap resamples. Indirect effect = 0.653, 95% bootstrap CI [0.184, 1.122]

Discussion

The primary finding of this study indicates that the association between perceived stress and self-reported halitosis among university students is statistically mediated by xerostomia. Additionally, self-reported halitosis was found to be associated with smoking, gingival bleeding, and lower tooth brushing frequency. The prevalence of daytime self-reported halitosis was 18.5%.

Following the methodology of a comparable study [30], participants reporting halitosis ‘constantly’ or ‘occasionally’ during the day were categorized as having self-reported halitosis, whereas those reporting ‘never’ or ‘rarely’ were classified as halitosis-free. Morning halitosis was considered physiological and excluded from the analysis [3, 40]. While the prevalence of self-reported halitosis in the literature ranges from 2.4% to 55% [23, 40, 42], the relatively lower rate observed in our study (18.5%) may be attributed to our methodological decision to exclude morning halitosis from the analysis, as well as the health-related knowledge of our sample, which consisted of dentistry and nursing students.

Consistent with previous reports, no significant associations were observed between self-reported halitosis and age, gender, academic year, or faculty [43–45]. Overall, participants demonstrated relatively satisfactory oral hygiene behaviors. While dentistry students tended to brush their teeth more frequently, nursing students were more likely to utilize interdental cleaning aids, tongue scrapers, and mouthwash. Previous studies have documented low dental floss utilization, insufficient tongue cleaning, and minimal mouthwash use among dentistry students [46–48]. Conversely, a study conducted with final-year dentistry students observed higher floss use [49], suggesting that oral health awareness may increase in the later stages of academic training. Given that the questionnaire evaluated oral hygiene behaviors over the past month a period coinciding with final examinations the demanding preclinical and clinical workload of dentistry programs may have prompted students to prioritize basic brushing over more time consuming routines during this timeframe [50].

Self-reported halitosis showed a tendency to decrease with higher brushing frequency and longer brushing duration; however, no statistically significant association was found with interdental cleaning, tongue cleaning, or mouthwash use. Similar outcomes have been reported elsewhere [40, 51], and the relationship between brushing frequency and halitosis is well-documented [52–54]. Smoking was significantly associated with halitosis, whereas alcohol consumption was not, aligning with previous literature [55, 56]. Although the cross-sectional design of our study precluded a clinical diagnosis of periodontitis, 55.8% of the participants reported gingival bleeding during brushing. Self-reported halitosis was significantly more prevalent among individuals with gingival bleeding, which is consistent with the established link between gingival inflammation and halitosis [57–60].

The prevalence of xerostomia in our sample was 67.8%. While the reported rate of xerostomia in the literature varies between 0.9% and 64.8% [39, 61, 62], a study conducted at Ankara University reported a xerostomia prevalence of 54.6%, noting its common occurrence in young populations as well [63]. Given that only 7% of participants reported regular medication use and systemic diseases were not associated with halitosis, this high prevalence cannot be attributed solely to pharmacological factors. The rigorous nature of both curricula, combined with the fact that data collection coincided with the final examination period, may have contributed to elevated stress levels and subsequent xerostomia [6, 64, 65]. Health sciences students might also be more attuned to minor intraoral changes, rendering them more likely to report dry mouth symptoms. It is worth noting that self-reported xerostomia does not always correspond to an objectively reduced salivary flow rate [20, 66]. Although xerostomia can originate from various systemic etiologies [67], stress is widely recognized as a major contributor to oral dryness [26, 64], and our regression model confirmed perceived stress as a significant predictor of xerostomia. These findings align with large scale studies pointing to psychological factors as risk factors for self-reported halitosis [68, 69]. While we hypothesized that stress leads to xerostomia and subsequent halitosis, the reverse pathway is also plausible: individuals who perceive bad breath may experience social embarrassment and heightened anxiety, thereby elevating their stress levels. Likewise, the sensation of dry mouth may reinforce negative emotions and stress perception. The cross-sectional design prevents us from determining the direction of these associations, and longitudinal studies are required to clarify their temporal sequence.

In line with the existing literature, perceived stress was higher among female students and dentistry students [70]. Furthermore, stress was not associated with oral hygiene habits, gingival bleeding, smoking, or alcohol consumption. While the literature regarding stress and oral hygiene remains mixed [71, 72], our results suggest that these students maintained their oral hygiene routines despite elevated stress, potentially due to social factors such as concern for personal appearance and peer relationships. The absence of an association between stress and gingival bleeding can likely be explained by the maintenance of adequate oral hygiene, as gingivitis is fundamentally driven by microbial plaque [73]. Smoking and alcohol use among university students may be more closely tied to social adaptation and peer influence rather than stress avoidance [74–76].

Although female students reported higher perceived stress, no significant gender differences were observed in the prevalence of xerostomia (68.7% vs. 65.9%; p = 0.575) or halitosis. This finding is consistent with our mediation model, indicating that perceived stress appears to be associated with halitosis only when accompanied by xerostomia. While cross-sectional data do not allow for establishing directionality, mediation analysis remains a useful approach for identifying potential intermediate variables that warrant further investigation in longitudinal designs [77, 78]. Because the stress xerostomia response may vary based on individual susceptibility [79], perceived stress does not inevitably culminate in xerostomia or halitosis.

Although evaluating all variables via self-report reports introduces the potential for common method bias, the observed associations remained specific to xerostomia and halitosis; perceived stress demonstrated no association with gingival bleeding or oral hygiene behaviors. This selectivity suggests that the findings are unlikely to be merely an artifact of a general tendency to over report symptoms under stress. Nonetheless, stressed individuals may possess a lower threshold for noticing oral dryness, and the perception of a dry mouth may, in turn, heighten attention regarding breath-related concerns. Future studies employing objective measures, such as sialometry and volatile sulfur compound analysis, would be valuable in distinguishing subjective perception from physiological alterations.

Limitations

This study has several limitations. The cross-sectional design does not allow causal inferences. Both halitosis and xerostomia were assessed through self-report rather than objective measurements, which may introduce perception bias and misclassification in both directions. Xerostomia was assessed using a single question rather than a validated multi-item scale, which may have limited measurement sensitivity. The absence of intraoral clinical examinations meant that factors such as tongue coating or periodontal pocket depth could not be verified. Potential confounding variables including dietary habits, caffeine and water intake, sleep quality, and anxiety or depression symptoms were not assessed. The response rate raises the possibility of self-selection bias, as students with higher stress or more severe halitosis may have been less inclined to participate. Data were collected during the final examination period, which may limit generalizability to other academic periods. No stratified sampling was applied across gender or grade levels. As a single center study among healthcare students, these results may not be directly applicable to the broader young adult population. Multi center longitudinal studies with objective clinical assessments are needed to clarify these associations.

Strengths

The sample size (n = 400) exceeded the power analysis requirement. Focusing on healthcare students allowed us to examine the stress oral health relationship in a group with relatively high oral health awareness. The validated PSS-10 enabled a standardized assessment of perceived stress. Data collection during the examination period allowed for assessment under conditions of naturally elevated stress. The use of a mediation model offers a perspective beyond simple correlational analyses, although the exploratory nature of this approach within a cross-sectional design should be taken into account when interpreting the findings.

Conclusions

This study found a high prevalence of both self-reported halitosis (18.5%) and xerostomia (67.8%) among dentistry and nursing students during the examination period. Perceived stress was not directly associated with self-reported halitosis; rather, this association was statistically mediated by xerostomia. These findings suggest that the association between perceived stress and self-reported halitosis may depend on the presence of xerostomia.

These findings point to xerostomia as a potential target for managing stress related oral health complaints in demanding academic settings. Strategies aimed at reducing stress and promoting adequate oral hydration may help improve oral comfort and quality of life among university students. Future research with objective measurements and longitudinal designs is needed to confirm these associations and to explore individual differences in the stress xerostomia response.

Supplementary Information

Supplementary Material 1. (20.1KB, docx)

Acknowledgements

The authors would like to thank all students who participated in this study.

Authors’ contributions

SE, ÖBD designed the study and developed the questionnaire. SE, ÖBD performed the statistical analysis. SE and ÖBD collected the data. SE wrote the first draft of the manuscript. SE, ÖBD critically reviewed and revised the manuscript. All authors read and approved the final manuscript.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not for profit sectors.

Data availability

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

This study was approved by the Health Sciences Ethics Committee of Çankırı Karatekin University (Meeting No: 18, Decision Date: 11.02.2025). The study was conducted in accordance with the Declaration of Helsinki. All participants provided informed consent electronically via Google Forms prior to completing the questionnaire.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Footnotes

Publisher’s note

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Associated Data

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Supplementary Materials

Supplementary Material 1. (20.1KB, docx)

Data Availability Statement

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

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