One-pack-a-day smoking habit will cost you at least 2 teeth every 10 years.
According to 30-year studies at Tufts University, chain smokers lost an average of 2.9 teeth after 10 years of smoking one pack a day. Non-smokers lost an average of 1.3 teeth after 10 years. A smoker that quit will reduce his or her toothloss to 1.7 teeth. (Source)
I am NOT a smoker, nor ever have been. I hate smoking and being around smoke. That said, I also hate the credence given by the press to bullshit studies even more... If you wish to advance an agenda (and don't we all?), it only *hurts* your case to attempt to do so via flawed arguments. It's tougher to design a study that attempts to isolate the varied factors and eliminate (or at least minimize) cross-correlation, but it's not impossible. 'Tis only an incompetent / lazy / biased (choose one) academician who would have designed so flawed a study.
Also see my critique on the study that "shows that kids lose weight by eating breakfast". More fodder.
But I think there's a lot more to it than just smoking. There could be other factors. Like stress levels of smokers versus non-smokers? Or diets? Or dental care coverage? When I worked in the restaurant industry, most of the people I worked with were smokers, and most were also uninsured. I could see how having dental insurance could help you keep your teeth longer.