Association between environmental tobacco smoke and periodontal disease: A systematic review

The aim of the present study was to systematically review the association between environmental tobacco smoke (ETS) and periodontal disease. The addressed focused question was "Is there a relationship between ETS and periodontal disease?". PubMed/MEDLINE and Google-Scholar databases were searched from 1987 up to March 2014 using different combinations of the following keywords: "Environmental tobacco smoke", "passive", "periodontal disease", "secondhand" and "smoking". Letters to the Editor, review articles, commentaries, case-reports and articles published in languages other than English were excluded.Thirteen studies were included. Nine studies were clinical and 4 studies were performed in-vitro. Five studies reported the odds ratios for periodontal disease to be significantly higher among individuals exposed to ETS than controls (non-smoking individuals unexposed to ETS). In 2 studies, ETS exposure showed no association with periodontal disease. In 2 studies, salivary aspartate aminotransferase, lactoferrin and albumin levels were reported to be significantly higher in individuals exposed to ETS than controls. In one study, levels of salivary interleukin-1β were reported to be significantly higher in individuals exposed to ETS than controls. The in-vitro studies reported ETS exposure to enhance the production of proinflammatory proteins and phagocytic activity of salivary polymorphonuclear leukocytes thereby contributing to periodontal disease. The association between ETS and periodontal disease remains debatable and requires further investigations.