Proximal alveolar bone loss in a longitudinal radiographic investigation: IV. Smoking and some other factors influencing the progress in individuals with at least 20 remaining teeth

In Sweden people in all age groups now have more remaining teeth than previously. An investigation has been made to identify some predictors of alveolar bone loss in a 10-year period in subjects with at least 20 remaining teeth. The material consisted of 349 individuals, examined radiographically, clinically, and by interview in 1970 and in 1980. These subjects, born in 1904-1952, constituted a subgroup, with regard to remaining teeth, of an unselected sample of the population of the old county of Stockholm. In the unselected sample statistically significant predictors of alveolar bone loss found in a stepwise multiple regression analysis were alveolar bone loss in 1970, age, number of lost teeth, and Russell's Periodontal Index (PI). In the subgroup the predictors were in the order Russell's PI and smoking. The prediction values (R2) of further variables were marginal. The analyses showed that there was an interaction between PI and smoking, implying that the effect of smoking on alveolar bone loss was increased in individuals with high PI values. Furthermore, a tendency was found for a dose-response effect of tobacco consumption. This tendency almost disappeared when controlling for PI.