Does periodontitis affect respiratory health?

DATA SOURCES: PubMed, Scopus and Cochrane Library were systematically searched for studies published up to October 2021. STUDY SELECTION: Two separate search strategies were employed: (1) In adults with periodontitis, what is the prevalence or incidence of respiratory diseases compared to healthy or gingivitis adults in cross-sectional, cohort or case -control studies. (2) In adults with periodontitis and respiratory disease, what are the effects of periodontal therapy compared to no or minimal therapy in clinical trials (randomised and non-randomised)? Respiratory diseases were defined as chronic obstructive pulmonary disease (COPD), obstructive sleep apnoea (OSA), asthma, COVID-19, and community acquire pneumonia (CAP). Exclusion criteria included non-English studies, individuals with severe systemic comorbidities, less than 12 months follow up, and a sample size less than 10 individuals. DATA EXTRACTION AND SYNTHESIS: Two reviewers independently screened the titles, abstracts, and selected manuscripts against the inclusion criteria. Disagreement was solved by consulting a third reviewer. Studies were classified according to the respiratory diseases investigated. Quality assessment was performed using various tools. Qualitative assessment was performed. Studies with sufficient data were included in meta-analyses. Heterogeneity was assessed using the Q test and I(2) index. Fixed and random effects models were used. Effect sizes were presented as odds-ratios, relative risks, and hazard ratios. RESULTS: 75 studies were included. Meta-analyses revealed statistically significant positive associations of periodontitis with COPD and OSA (p < 0.001) however no association for asthma. Four studies showed positive effects of periodontal treatment on COPD, asthma, and CAP.