Search strategy and selection criteria

Relevant studies were identified by searching the following data sources between 1950 and 1 October 2016: Pubmed, Embase, Scopus, Web of science and abstracts from the 2004–2015 European Renal Association European Dialysis and Transplant Association (ERA-EDTA) Congress. We used Medical Subject Headings (MeSH) and text words of chronic kidney disease, renal replacement therapy, dialysis, kidney transplantation, periodontal diseases and mortality by formulating optimally sensitive search strategies, see Supplementary Search Strategy. Additionally, manual review of reference lists of all included articles was also performed. All potentially eligible studies were retrieved and examined without the limit of languages. If the same cases were reported in more than one study, only the study with the most complete data was included.