Key result
Nighttime toothbrushing is linked to ~21% lower odds of hypertension.
Why the study?
Although nighttime oral hygiene may be particularly important because salivary clearance and antimicrobial defenses decline during sleep, the association between nighttime toothbrushing and hypertension and the mediating role of systemic inflammation remain largely unexplored.
Is nighttime toothbrushing associated with lower odds of prevalent hypertension in Korean adults, and is this association mediated by systemic inflammation?
Cross-Sectional (n=33,224)
Yes
Is nighttime toothbrushing associated with lower odds of prevalent hypertension in Korean adults, and is this association mediated by systemic inflammation?
Nighttime toothbrushing is independently associated with 21% lower odds of prevalent hypertension regardless of daytime brushing frequency, partly mediated through lower systemic leukocyte inflammation.
Answers are grounded in this paper and cite their sources.
Nighttime toothbrushing association with lower hypertension odds merits prospective trials; does not yet alter clinical recommendations.
Because salivary clearance and antimicrobial defenses decline during sleep, allowing overnight bacterial accumulation and periodontal inflammatory activity, nighttime oral hygiene may be particularly important; however, its association with hypertension remains largely unexplored. We investigated whether nighttime toothbrushing is associated with hypertension, and whether systemic inflammation mediates this association. We analyzed the cross-sectional 2016 to 2023 Korea National Health and Nutrition Examination Survey (KNHANES), including 33,224 adults, using survey-weighted analyses. Participants were classified as Night (brushing teeth after dinner or before bedtime) or None. After adjustment for morning and lunch brushing and risk factors, nighttime toothbrushing was associated with lower odds of hypertension (OR, 0.790; 95% CI, 0.686–0.910; P = 0.001). The association was present at both low (OR, 0.830; 95% CI, 0.702–0.982; P = 0.030) and high daytime brushing frequency (OR, 0.710; 95% CI, 0.555–0.908; P = 0.006), with no significant interaction (P for interaction = 0.299). In mediation analysis, the association was partly mediated by white blood cell count (indirect effect, − 0.539 percentage points; 95% bootstrap CI, − 0.837 to − 0.296; P = 0.004). Nighttime toothbrushing was associated with lower odds of hypertension, supported by a WBC-related inflammatory pathway. These findings suggest that nighttime toothbrushing may represent a simple, modifiable behavior warranting further investigation in hypertension.
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Kim et al. (2026) conducted a cross-sectional in Hypertension (n=33,224). Nighttime toothbrushing (brushing teeth after dinner, before bedtime, or at both times) vs. No nighttime toothbrushing (None group) was evaluated on Prevalent hypertension (systolic blood pressure ≥140 mmHg, diastolic blood pressure ≥90 mmHg, or current use of antihypertensive medication) (OR 0.790, 95% CI 0.686–0.910, p=0.001). Nighttime toothbrushing was independently associated with 21% lower odds of prevalent hypertension among Korean adults.
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