Age-stratified associations of oral hygiene care with dental caries and periodontitis: cross-sectional analysis of seventh Korea national health and nutrition examination survey.

OBJECTIVES: This cross-sectional study aimed to demonstrate the association between oral hygiene care behaviors specifically toothbrushing frequency (TBF), interproximal cleaning, and electric toothbrush use and tooth caries or periodontitis, stratified by age. METHODS: Representative data from the Korea National Health and Nutrition Examination Survey during 2016-2018 (KNHANES VII) was used to evaluate the association between oral hygiene behaviors and tooth caries or periodontitis as stratified by three age groups (14 or 20-39 years, 40-59 years, and 60 years or over). Caries and periodontitis were assessed using the decayed, missing, and filled surface (DMFS) and Community Periodontal Index (CPI), respectively. Finally, 12,867 individuals aged 14 years or older for caries, and 11,538 people aged 20 years or older for periodontitis were analyzed. RESULTS: Lower TBF was significantly associated with higher DMFS in the overall analysis (IRR = 1.05; 95% CI, 1.03-1.07), but this association persisted only in individuals aged ≥ 60 years after age stratification (IRR = 1.05; 95% CI, 1.02-1.08). Dental floss non-use was consistently associated with higher CPI across all age groups (aRRs = 1.26-1.38), with the strongest effect in the youngest group. CONCLUSION: Toothbrushing frequency and dental flossing were differentially associated with caries and periodontitis, with notable age-specific patterns. These findings support tailored oral hygiene strategies based on age and target disease.