To evaluate (1) whether periodontitis has an influence on the prevalence/incidence of respiratory diseases (chronic obstructive pulmonary disease [COPD], asthma, community‐acquired pneumonia [CAP], obstructive sleep apnoea [OSA] and COVID‐19), and (2) what is the impact of periodontal therapy on the onset or progression of respiratory diseases.

An electronic search was performed on Pubmed, Cochrane Library and Scopus databases up to October 2021, to identify studies answering the PECOS and PICOS questions.

Seventy‐five articles were selected. Meta‐analyses identified statistically significant associations of periodontitis with COPD (n_studies = 12, odds ratio [OR] = 1.28, 95% confidence interval [CI] [1.16; 1.42], p < .001), and OSA (n_s = 6, OR = 1.65, 95% CI [1.21; 2.25], p = .001), but not for asthma (n_s = 9, OR = 1.53, 95% CI [0.82; 2.86], p = .181). For acute conditions, two studies were found for CAP, while for COVID‐19, significant associations were found for the need of assisted ventilation (n_s = 2, OR = 6.24, 95% CI [2.78; 13.99], p < .001) and COVID‐related mortality (n_s = 3, OR = 2.26, 95% CI [1.36, 3.77], p = .002). Only four intervention studies were found, showing positive effects of periodontal treatment on COPD, asthma and CAP.

A positive association between periodontitis and COPD, OSA and COVID‐19 complications has been found, while there is a lack of intervention studies.