Cigarette smoking is a significant risk factor for periodontaldiseases and implant treatments. Smoking control is regarded as a key to the success of dental treatments as well as the well-being of the patients. The aim of this study was to reviewthe effects of smoking on periodontal health, and the results of periodontal therapy and implant treatments. Also, in vitro, microbiological, immunological and epidemiological relationships were studied. In vitro studies show that smoking interferes with normal healing process and increased tissue destruction. There is still controversy on the population of microbes of smokers. Smokers showed significantly less gingival inflammation and bleeding on probing compared with non-smokers. After periodontal treatments, a compromised clinical outcome was noted for smokers in terms of pocket depth reduction and gain in attachment levels. In conclusion, data from in vitro, epidemiological, cross-sectional and case-control studies strongly suggest that quitting smoking is beneficial to patients before periodontal and implant treatments.