Data sources Cochrane Oral Health Trials Register, Cochrane Central Register of Controlled Trials, MEDLINE, Embase, CINAHL, Chinese Biomedical Literature Database, China National Infrastructure, US National Institutes of Health Ongoing Trials Registry, WHO Clinical Trials Registry, Sciencepaper Online, 19 Chinese dental and nursing journals. Reference lists of included studies were also screened.

Study selection Studies were included if they explored oral care with the purpose of reducing pneumonia compared to no oral care, usual care or other oral care measures. Only randomised controlled trials were included which could be either parallel design or cluster RCTs with randomisation by care facility. No restrictions were placed on language, year of publication or publication status.

Data extraction and synthesis Two independent reviewers undertook screening for inclusion, data extraction and assessment of risk of bias. The Cochrane tool for risk of bias was used to assess quality of the studies. Synthesis was mainly narrative, though numerical results were combined where feasible.

Results Four studies were included, all of which were parallel RCTs. All were judged to be at high risk of bias due to lack of blinding. One study suggested that oral care may reduce pneumonia associated death, though evidence was low quality and should be treated with caution. There was no high quality evidence available to indicate which oral care methods may be most effective in reducing pneumonia.

Conclusions It was not possible to establish the effects of professional oral care on nursing home-acquired pneumonia due to the limited number of studies and low quality evidence. Further trials are needed to draw reliable conclusions.