In one study, 495 healthy men had their teeth examined every three years. The men were divided into three groups: those who never used tobacco products, those who continuously smoked and those who smoked at the beginning of the study but later quit. Smokers lost an average of 2.9 teeth after 10 years of smoking one pack a day, while non-smokers lost an average of 1.3 teeth after 10 years. In men who quit, the tooth loss was 2.4 teeth after 10 years of smoking one pack a day, and this decreased to 1.7 lost teeth after they quit.