An umbrella review of the evidence linking oral health and systemic health: from the prevalence to clinical and circulating markers

Oral conditions are highly prevalent worldwide. Recent studies have been supporting a potential bidirectional association of oral disorders with systemic noncommunicable diseases (NCDs). Robust evidence supports the greater prevalence of oral conditions in people suffering from NCDs limiting the ability of oral self-care. As for the relationship with other NCDs, the lines of evidence have increased exponentially but not always with the proper coherence. This umbrella review of meta-analyses appraises the strength and validity of the evidence for the association between oral health and systemic health. An extensive search included systematic reviews that have provided meta-analytic estimates on the association of an oral condition with a NCD. The overall strength of evidence was found to be unfavorable and with methodological inconsistencies. Twenty-two NCDs, four types of cancer and circulating levels of CRP were strongly associated with oral diseases. Among the significant NCDs are diabetes mellitus, cardiovascular diseases, depression, neurodegenerative conditions, rheumatic diseases, inflammatory bowel disease, gastric helicobacter pylori, stroke, obesity, diabetes mellitus or asthma. Most evidence is unlikely to change which indicates a relatively robust consistency of the available body of evidence. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work is financed by national funds through the FCT Foundation for Science and Technology, I.P., under the Project UIDB/04585/2020. The study sponsor had no role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the article; and decision to submit the article for publication. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors