Tobacco smoking is associated with many serious chronic diseases, such as carcinomas, cardio-pulmonary diseases, low birth weight in children, as well as with many oral health diseases. It is also associated with a detrimental impact on oral health, such as an increased risk of gum (periodontal) diseases. In addition, dental implant failure is more common in tobacco smokers than among non-smokers, and infection of implant sight among smokers is also more prevalent. Tobacco can be consumed via the mouth in many forms, varied from smoking to smokeless tobacco chewing by itself or combined with betel nut. Oral manifestations most likely result from the many chemicals including irritants, toxins, and carcinogens found in the smoke emitted from burning tobacco, but they may also arise from dryness of the mucosa by the high intra-oral temperature, change in pH, alteration of the immune system, or altered resistance to fungal or viral infections. Other lesions include halitosis, staining of teeth and composite restorations, decreased sensations of taste and smell, and nicotinic gastritis and keratosis. Most of these pathological symptoms resolve after cessation of tobacco smoking. The aim of this article is to educate on the effect of tobacco smoking on oral health, particularly on the risk of periodontal conditions, dental implants associated infections, and oral cancers.

**Tobacco Smoking and Oral Health Problems: ** Periodontal (gums) diseases, including gingivitis and periodontitis, are common human bacterial infections that affect the gingiva and bone supporting the teeth. Gingivitis is known as inflammation which is limited to the marginal gingival tissues and is usually caused by tobacco smoking and lack of oral health. Gingivitis is usually treatable with medical treatment and good oral hygiene at home. Untreated gingivitis (inflammation of gingiva) may progress to the inflammation of gums (periodontitis). Periodontitis refers to massive inflammation that arises from irreversible loss of gum supporting tissue and bone. Approximately 15% of the adult population has severe long-standing periodontitis.  Gingival recession may result from periodontal destruction and exposure to tobacco irritants and chemicals which affect oral health. Those exposed root surfaces are at high risk of developing root surface plagues. Root surface plagues among people with gingival recession are more common in tobacco smokers than in non-smokers. Research shows that tobacco smoking is a major risk factor for the development of periodontal diseases and other oral health problems. Disease severity increases with the frequency and quantity of tobacco smoking. Tobacco smokers accumulate markedly more dental stones than non-tobacco users, and the quantity of oral stones is correlated with the frequency of smoking. Tobacco smoking is also linked with loss of dental bones and destruction of oral health. The side effects of tobacco smoking on the periodontium correlates well with both the quantity of daily consumption and the duration.

Approximately half of the cases of oral health problems in the United States have been attributed to tobacco smoking. Smokers were recorded to have a 2 to 3 times greater risk of severe teeth attachment loss. In the analysis that adjusted for different oral hygiene routines, patient age, sex, and socioeconomic status, smokers had deeper periodontal pockets, increased alveolar bone loss, increased tooth mobility, and more tooth loss than did non-smokers. With relation to oral health problems, low mood depression and poor oral hygiene seem to play an important interactive role with tobacco smoking. Sudden destructive gingivitis is also strongly correlated with tobacco use. Although the precise cause of this disease remains unknown, it tends to occur most frequently in the early teenage group and adults. The bleeding from gums in smokers is ‘less severe’ than in non-smokers, which could be related to the constriction of blood vessels, an effect of the nicotine which is present in tobacco.  Effects of Tobacco Smoking on Periodontal Therapy Outcomes: Smokers respond to medical treatment less favorably than non-smokers in non-surgical and surgical oral therapy. Tobacco smokers exhibited less improvement when compared with non-smokers in terms of oral health achievement like pocket-depth reduction, resolution of gingival inflammation, and clinical attachment level. Heavy tobacco smokers (smoking >10 cigarettes per day) exhibited a lower degree of probing-depth reduction and less gain in clinical attachment level than did ex-smokers and non-tobacco smokers during active periodontal treatment. In addition, current tobacco smokers have poor healing. However, up to 80-90% of refractory periodontitis patients are smokers, which adversely affects oral health outcomes related to treatments.