Some risk factors for periodontal bone loss in 50-year-old individuals. A 10-year cohort study

Abstract

Objective: The aim of this 10-year prospective study of 50-year-old individuals was to analyze the incidence of periodontal bone loss and potential risk factors for periodontal bone loss.

Methods: The subject sample was generated from an epidemiological survey performed in 1988 of subjects living in the County of Värmland, Sweden. A randomized sample of 15% of the 50-year-old inhabitants in the county was drawn. At the 10-year follow-up in 1998, 320 (75%) of the 449 individuals examined at baseline were available for re-examination, out of which 4 had become edentulous. Full-mouth clinical and radiographic examinations and questionnaire surveys were performed in 1988 and 1998. Two hundred and ninety-five individuals (69%) had complete data for inclusion in the analysis of radiographic bone changes over 10 years. Non-parametric tests, correlations and stepwise multiple regression models were used for statistical analysis of the data.

Results: The mean alveolar bone level (ABL) in 1988 was 2.2 mm (0.05) and a further 0.4 mm (0.57) (p=0.000) was lost over the 10 years. Eight percent of the subject sample showed no loss, while 5% experienced a mean bone loss of >/=1 mm. Smoking was found to be the strongest individual risk predictor (RR=3.2; 95% CI 2.03-5.15). When including as smokers only those individuals who had continued with the habit during the entire 10-year follow-up period, the relative risk was slightly increased (3.6; 95% CI 2.32-5.57). Subjects who had quit smoking before the baseline examination did not demonstrate a significantly increased risk for disease progression (RR=1.3; 95% CI 0.57-2.96). Stepwise multiple regression analysis revealed that smoking, % approximal sites with probing pocket depth >/=4 mm, number of teeth and systemic disease were significant explanatory factors for 10-year ABL loss (R(2)=0.12). For never smokers, statistically significant predictors were number of teeth, mean ABL, % periodontally healthy approximal sites and educational level (R(2)=0.20).

Conclusion: The inclusion of smokers in risk analysis for periodontal diseases may obstruct the possibility to detect other true risk factors and risk indicators.