The World Health Organization (WHO) cites tobacco‐related death and illness as drivers of poverty, as they force individuals to bear high medical expenses. Furthermore, tobacco contains over 7000 toxic chemicals including several known to be human carcinogens. Given this, tobacco smoking is associated with numerous preventable chronic diseases. In addition to the well‐known tobacco‐related lung cancer, smoking is also a key risk factor for oral cancer, esophageal cancer, larynx cancer, and pancreatic cancer. Stopping tobacco use is often said to be the most important element of cancer prevention in the world today. Although smoking has decreased in some countries, there are still ≈120 million smokers globally. The prevalence of smoking in South Korea is among the highest in the world. In 2016, ≈40.7% of men and 6.4% of women over the age of 19 were smokers in Korea. Therefore, government and public health professionals have made intensive efforts to reduce tobacco use by implementation of strong and effective tobacco control polices and measures, such as tobacco tax increases, media campaigns.

As social interest in quitting smoking has increased, interest in electronic cigarettes has increased. Electronic cigarettes are battery‐operated devices that are designed to vaporize a mixture of nicotine and other chemicals, which heat the vapor via a battery. Recently electronic cigarettes have been commonly used as a smoking cessation aid in South Korea. Some advertisements describe electronic cigarettes as a healthier alternative to conventional cigarettes. As this perception of electronic cigarettes has become widespread throughout the culture, the number of electronic cigarette vapers has been growing rapidly. One prior study suggested that people choose electronic cigarettes as a smoking substitute; however, the risk of developing smoking‐related diseases, particularly periodontal diseases, could still be high, as there is a lack of research about the safety of electronic cigarettes. Thus, this phenomenon should be urgently examined.

Periodontal disease is a chronic inflammatory condition characterized by destruction of the periodontal tissues, resulting in loss of connective tissue attachment, loss of alveolar bone, and the formation of pathological pockets around the diseased teeth. According to the 2013–2015 Korean National Health and Nutrition Examination Survey (KNHANES), 31.5% of people have periodontal disease (51.8% men; 48.2% women). Furthermore, oral diseases in adult life are linked to other systemic illnesses, making it important to manage oral diseases, as doing so can prevent stroke, cancer, heart disease, obesity, and diabetes.

Smoking is the single most important environmental factor associated with non‐inflammatory diseases of the oral cavity, as well as being an important cause of periodontitis, which is a limiting factor in dental health. Not only smoking, vaping could influence on periodontal health. Some previous study shows that direct exposure to electronic liquids has also been shown to produce harmful effects in periodontal ligament cells. Reactive aldehydes derived from electronic cigarette aerosol can cause protein carbonylation which may lead to destruction of matrix and bone loss during periodontitis. But still, the use of electronic cigarettes has increased for various reasons, including the perception that it is less harmful than conventional cigarette smoking and that it can be used as a means to quit smoking. Therefore, it is necessary to investigate the possible association between electronic cigarette and periodontal diseases and provide evidences that could support determining whether or not vaping is safer than smoking. To the authors' knowledge, there is no clinical study that shows the association of conventional cigarette smoking and electronic cigarette vaping with periodontal diseases using community periodontal index (CPI) score. The hypothesis of this study is that vaping has significant relation to periodontal disease just as much as smoking does.

Consequently, the current study sought to examine the association of electronic cigarette and conventional cigarettes individually with periodontal disease among South Korean adults.