RESUMO
BACKGROUND: A J-shaped relationship of body mass index (BMI) with severe periodontitis has been reported. However, it is unknown for other anthropometric indexes in young adults. METHODS: A cross-sectional study examined the relationships in 325 military men and women, aged 20 to 45 years in Taiwan. Anthropometric indexes included BMI, waist circumference (WC), and waist-to-height ratio (WHtR). The severity of localized periodontitis was defined as healthy (n = 42), Stage I (initial) (n = 228), and Stage II/III (moderate/severe) (n = 55) according to the 2017 Periodontal Diseases Classification. Smooth curve fitting and multiple logistic regression analyses adjusting for age, sex, betel nut consumption, and smoking were used to determine the threshold effect between various anthropometric and the risk of localized Stage II/III periodontitis. RESULTS: In the spline smoothing plot, the turning points for BMI, WC, and WHtR were 26.1 kg/m2 , 90.0 cm, and 0.50, respectively, and a J-shaped relationship was found for BMI (the likelihood ratio test, P <0.001). In the multiple logistic regressions, BMI ≥27.0 kg/m2 , WC ≥90.0 cm and WHtR ≥0.50 were associated with higher risk of localized Stage II/III periodontitis than their counterparts (24.0 to 26.9 kg/m2 for BMI) (odds ratios [OR] and 95% confidence intervals: 4.16 [1.39 to 12.49], 2.65 [1.01 to 7.11], and 2.95 [1.20 to 7.24], respectively; all P values <0.05). However, the risk for BMI <24.0 kg/m2 was not significant (OR, 1.47 [0.47 to 4.54]). CONCLUSION: In young adults, obesity defined by various anthropometrics was consistently associated with localized Stage II/III periodontitis and a J-shaped association was suggestive for BMI.