Abstract
Background
Oral diseases, such as dental caries and periodontitis, and obesity are both prevalent and share common risk factors. Although obesity, defined as body mass index (BMI) ≥30 kg/m2, has been associated with poorer oral health, the association between long-term average BMI, changes in BMI, and oral health status in adulthood remains unclear. This study aims to investigate the associations between long-term average BMI, changes in BMI, and self-rated oral health status in the adult Norwegian population.
Methods
We conducted a prospective cohort study, comprising 17,088 individuals (58.6% females) who participated in the population-based Trøndelag health study (HUNT). The cohort was established using data from HUNT3 (2006-08), and participants were subsequently followed up for self-rated oral health status collected at HUNT4 (2017-19). At HUNT3 (the baseline), weight and height were measured directly, while retrospective data on weight and height were retrieved from measurements conducted at HUNT1 (1984-86) and HUNT2 (1995-97). Average BMI and BMI changes over 10- and 20-year periods were calculated. In addition, 10-year average waist circumference (WC) and corresponding WC changes were assessed. We estimated odds ratio (OR) with 95% confidence interval (CI) using multivariable logistic regression models after adjustment for potential confounders.
Results
In HUNT4, 1,500 participants (8.8%) rated their oral health as poor or very poor. The fully adjusted ORs for poor oral health among participants with an average BMI ≥30 kg/m² over 10- and 20-year periods were 1.5 (95% CI, 1.3–1.7) and 1.5 (95% CI, 1.3–1.8), respectively, when compared with normal weight individuals. However, after adjustment for baseline BMI, the associations between long-term average BMI and poor oral health were noticeably weakened. Additionally, compared with stable BMI, both BMI loss (≥2.5 kg/m²) and BMI gain (≥5 kg/m²) over 10-years were associated with poor oral health, with ORs of 1.6 (95% CI, 1.3–2.2) and 1.5 (95% CI, 1.2–1.9), respectively. We observed a similar but weaker pattern for average WC and changes in WC over 10-year period.
Conclusion
Our findings suggest that average BMI ≥30 kg/m² over the long term and both BMI gain and BMI loss were associated with poorer oral health. However, the association with long-term average BMI and poor oral health was attenuated after adjustment for baseline BMI.
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