Objectives: The purpose of this study was to investigate whether there is a causal relationship between periodontitis and breast cancer by Mendelian randomization analysis. Materials and methods: We performed a two-sample bidirectional Mendelian randomization (MR) analysis using publicly released genome-wide association studies (GWAS) statistics. The inverse-variance weighted (IVW) method was used as the primary analysis. We applied complementary methods, including weighted median, weighted mode, simple mode, MR-Egger regression, and MR-pleiotropy residual sum and outlier (MR-PRESSO) to detect and correct for the effect of horizontal pleiotropy. Results: IVW MR analysis showed no effect of periodontitis on breast cancer (IVW OR=0.99, P =0.14). Similarly, no significant causal relationship between breast cancer and periodontitis was found in reverse MR analysis (IVW OR=0.95, P =0.83). The results of MR-Egger regression, weighted median, and weighted mode methods were consistent with those of the IVW method. Based on sensitivity analyses, horizontal pleiotropy is unlikely to distort causal estimates. Conclusions: Although observational studies have reported an association between periodontitis and breast cancer, the results of our MR analysis do not support a causal relationship between periodontitis and breast cancer. Clinical relevance: Mendelian randomization study can more clearly analyze the causal relationship between periodontitis and breast cancer, in order to provide a certain reference for clinicians and deepen the understanding of the relationship between periodontitis and breast cancer, to explore more possible associations between periodontitis and systemic diseases.

Background: The purpose of this study was to investigate whether periodontitis is associated with dietary vitamin C intake, using data from The National Health and Nutrition Examination Survey (NHANES) 2009–2014. Methods: The study included 5145 adults (age ≥ 30 years) with periodontitis as a dichotomous variable and daily intake of vitamin C as a continuous variable. Multiple sets of covariates, such as age, sex, number of flossing, etc., were selected. Using EmpowerStats version 3.0, multivariate logistic regression analysis and hierarchical analysis were performed on the data, and curve fitting graphs were made. Results: There were no statistically significant differences (P > 0.05) between the four dietary vitamin C intake groups (quartiles, Q1–Q4) and covariates (drinking alcohol and hypertension). The low VC intake group (Q1) was more prone to periodontitis than Q2, Q3, and Q4 (all OR < 1.00). A threshold nonlinear association was found between vitamin C (mg) log10 transformation and periodontitis in a generalized additive model (GAM) (P = 0.01). Conclusion: The relationship between dietary vitamin C intake and the likelihood of periodontitis was non-linear. The smallest periodontitis index occurred when dietary vitamin C intake was 158.49 mg. Too little or too much vitamin C intake increases periodontitis.

Background: The American Heart Association has developed a novel cardiovascular health indicator called Life’s Essential 8 (LE8). However, no one has reported using LE8 to assess periodontitis. This study aimed to investigate the association between LE8 and periodontitis in American adults. Methods: Data from the National Health and Nutrition Examination Survey (NHANES) from 2009 to 2014 were used for this investigation. LE8 was the independent variable, and it is divided into three grades: high, moderate, and low. Periodontitis was the dependent variable, and the classification of periodontitis was based on the criteria of Eke in 2012. Multivariable logistic regression models were used to explore the relationship between LE8 and periodontitis. Results: A total of 9,039 participants with an average age of 52.16 ± 14.21 years were enrolled in this study, of whom 48.29% were male and 51.71% were female. The mean and standard deviation of LE8 was 66.29 ± 14.57, and the prevalence of periodontitis was 50.48% overall. The LE8 score and periodontitis in the fully adjusted logistic regression model showed a negative correlation (OR = 0.98; 95% CI, 0.98–0.99, p < 0.001). This result persisted when Life’s Essential 8 was categorized into low, moderate, and high groups. Compared with those in the lowest group, those in the highest LE8 group had a 47% decreased risk of periodontitis (OR = 0.53; 95% CI, 0.46–0.66, P < 0.001). Conclusions: This cross-sectional investigation revealed a negative relationship between the LE8 score and the likelihood of periodontitis.

Background: Various data have been obtained on the relationship between body mass index (BMI) and C-reactive protein (CRP) and periodontitis. The aim of this study was to determine whether CRP/BMI are associated with periodontitis using data from the National Health and Nutrition Examination Survey (NHANES) database. Methods: A cross-sectional analysis of data from 3602 participants in the 2009–2010 NHANES cycle was performed. The definition of periodontitis was used to divide participants into four groups according to the criteria of Eke. Correlations between CRP/BMI and periodontitis were tested for statistical significance by means of descriptive statistics, multivariate regression, and subgroup-stratified analyses, with and without adjustments for confounders (such as age and sex). Results: There were no statistically significant differences (p > 0.05) regarding BMI and the development of periodontitis. After adjustment for age, sex, race, marital status, annual family income, alcohol consumption, hypertension, smoking, chronic pulmonary disease, cardiovascular disease, diabetes, flossing, and arthritis, CRP correlated significantly with the development of periodontitis in the subgroups stratified by obesity, with an odds ratio (OR) of 1.2 (95% CI, 1.0 to 1.5). Conclusion: Through data analysis, we found an association between CRP levels and periodontitis prevalence in the American population, although this association was only present in the obese population. While there are several hypotheses about the underlying mechanism, further studies are needed to validate these findings.

Background and objective: Bone mineral density (BMD) and periodontitis have been the subject of many studies. However, the relationship between skull (including mandible) BMD and periodontitis has not been extensively studied. An objective of this cross-sectional study was to examine the relationship between skull BMD and periodontitis using data from the National Health and Nutrition Examination Surveys (NHANES) for 2011–2012 and 2013–2014. Materials and methods: From NHANES 2011–2014, 3802 participants aged 30–59 were selected. We divided the skull BMD level into quartiles to check the distribution of variables. Periodontitis was defined by the Centers for Disease Control and Prevention (CDC) and the American Association of Periodontology (AAP) in 2012. Multivariate logical regression analysis was used to explore the independent relationship between skull BMD and periodontitis. The generalized additive model (GAM), smooth curve fitting (penalty spline) and threshold effect analysis was used to evaluate dose-response relationship between skull BMD and periodontitis and the potential nonlinear relationship between skull BMD and periodontitis. Finally, subgroup analysis and interaction test were conducted to determine the role of covariates between skull BMD and periodontitis. Results: The overall average skull BMD of 3802 participants was 2.24g/cm2, the average age was 43.94 years, and the prevalence of periodontitis was 41.03%. In the fully adjusted logistic regression model, skull BMD and periodontitis showed an independent negative correlation (OR 0.73, 95% CI 0.59–0.90, P = 0.0032) and a linear relationship. Compared with the lowest quartile array (Q1:1.22–1.98) of skull BMD, the highest quartile array(Q4: 2.47–3.79) had a significantly lower risk of periodontitis (OR 0.70,95% CI 0.56–0.87, P = 0.0014). Subgroup analysis showed a highly consistent negative correlation between skull BMD and periodontitis. In the interaction test, people with moderate poverty income ratio (1.57–3.62) and those who had more than 12 alcohol drinks in the past year had a lower risk of periodontitis. Conclusions: This result suggested that periodontal disease can be related to low skull BMD, for those people, oral hygiene and health care should be more closely monitored. Validation of our findings will require further research.