That's incorrect, at least in the case of cigarettes. According to the CDC, you have twice the risk of gum disease if you smoke versus nonsmokers. They also state that the more you smoke and the longer you smoke, the greater your risk. That doesn't directly imply a causal link, but it sure winks really obviously in the direction of one.
For some perspective, "Twice the risk of gum disease" is pretty tame. Try losing 90% of your adult teeth... That's the level of dental prohlem that lomg-term addicts have to deal with, after 5-10 years of street life. Smoking cigarettes doesn't even come close.
https://www.cdc.gov/tobacco/campaign/tips/diseases/periodont...