The aim of this review was to evaluate the causal association between smoking and tooth loss.

The reviewers searched Medline, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL) and hand searched a number of relevant journals. English language studies investigating associations between smoking and tooth loss and reporting the effect size were included. Quality was assessed using the modified Newcastle–Ottawa Scale.

They identified six cross-sectional and two cohort studies  involving 58,755 individuals and found:-

• All studies reported significant associations, although the strength of the association was usually moderate.
• Four studies reported dose–response relationships between exposure to smoking and the risk of developing tooth loss.
• A decrease in the risk of tooth loss for former smokers was evident in six studies.

They concluded:-

Based on the consistent evidence found with the existing biological plausibility, a causal association between smoking and tooth loss is highly likely. Further studies using a cohort design and different populations are necessary to confirm this association.

Hanioka T, Ojima M, Tanaka K, Matsuo K, Sato F, Tanaka H.Causal assessment of smoking and tooth loss: A systematic review of observational studies. BMC Public Health. 2011 Apr 8;11:221