Combined total immunoglobin G (IgG) levels were obtained by summing concentrations for all oral bacteria measured.RESULTS: IgG antibody levels were substantially lower among current and former smokers (1,697 and 1,677 ng/mL, respectively) than never smokers (1,960 ng/mL; p trend = 0.01), but did not vary by other factors, including body mass index, diabetes, physical activity, or by dietary factor