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 19,931 participants, 3,802 were screened and included with no missing values in the study. We examined the distribution of variables by grouping the skull BMD levels into quartiles. Periodontitis is defined by the Centers for Disease Control and Prevention (CDC) and the American Periodontal Association (AAP) in 2012. An interaction test was conducted using stratified and adjusted logistic regression models, and multivariate logistic regression analysis was performed, along with curve fitting and a threshold effect analysis were performed on the relationship between skull BMD and periodontitis. Results: The results showed a negatively relationship between skull BMD and the risk of periodontitis. Although the inflection point was found (the skull BMD= 2.89g/cm 2 ), it was not statistically significant, indicating that the skull BMD and periodontitis are linearly related, which 1 unit increase in the skull BMD (g/cm 2 ) was associated with a 30% (OR=0.70; CI=0.57, 0.87; p=0.0010) reduction in the risk of periodontitis events. Conclusions: Periodontal disease may 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.

The authors have declared no competing interest.

The author of YL received the awards from the Science and Technology Plan Project of Guiyang in 2014([2014]003) and 2019 ([2019]9-7-13). URL?http://kjj.guiyang.gov.cn/fzlm/fzlmgywm The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Approval of both datasets was granted by NCHS Research Ethics Review Board (ERB), protocol #2011-17 and informed consent was received from all participants.

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