Tobacco Control Policies and Tooth Loss: A Difference-in-Differences Study

This study estimated the effects of state cigarette taxes, retail cigarette prices, and indoor smoking bans on smoking behavior and tooth loss among US adults. State policy data were merged with individual data from 15 cycles of the Behavioral Risk Factor Surveillance System (1995-2012; N = 3,840,519). Covariate-adjusted 2-way fixed effects linear and Poisson models estimated risk differences and risk ratios for contemporaneous and cumulative (10-y average) exposures, complemented by heterogeneity-robust difference-in-differences estimators; the parallel trends assumption was assessed empirically and with causal diagrams. A $1.00 increase in the combined cigarette tax reduced current smoking by 0.35 percentage points (95% CI: -0.56, -0.13) and increased quitting by 0.51 percentage points (95% CI: 0.19, 0.82); the smoking reduction persisted under sustained exposure (10-y average tax: -0.47 percentage points; 95% CI: -0.95, 0.01), and retail prices showed similar effects. In contrast, taxes and prices showed no robust effect on tooth loss. Complete edentulism was unrelated to taxes in every covariate-adjusted specification (current-year tax: 0.08 percentage points; 95% CI: -0.14, 0.31), and loss of ≥6 teeth showed only a weak, statistically nonsignificant protective association that was strongest for cumulative exposure (10-y average tax: -0.44 percentage points; 95% CI: -1.17, 0.30). Indoor smoking bans (restaurant and mall/grocery) were not associated with lower smoking or less tooth loss; point estimates were small and several were positive (e.g., restaurant ban and current smoking: +0.11 percentage points; 95% CI: -0.34, 0.55), and the mall/grocery ban failed a negative control test. Cigarette taxation and pricing remain powerful levers for reducing smoking, but a population-level benefit for tooth loss could not be demonstrated within this 18-y window, and indoor smoking bans showed no robust effect on either outcome; the suggestive association between sustained tax exposure and severe tooth loss warrants evaluation over longer horizons.