Association between smoking intensity and duration and tooth loss among Finnish middle-aged adults: The Northern Finland Birth Cohort 1966 Project.

BACKGROUND Smoking is a risk factor for oral diseases and tooth loss. Our aim was to analyze the association between smoking intensity and duration and tooth loss among middle-aged Finnish adults who have enjoyed access to subsidized dental care since childhood. METHODS This study was based on the Northern Finland Birth Cohort 1966 (NFBC1966) Project, a representative sample of Finnish 46-year-olds. Altogether 1946 46-year-olds participated in a survey and comprehensive clinical oral examinations. We measured smoking exposure in pack-years (intensity) and years of smoking (duration) combined with recent smoking status (current, former, occasional or never). We used negative binomial regression models to estimate the unadjusted and adjusted relative risks (RR) with corresponding 95 % confidence intervals (CI) for tooth loss as an outcome. Gender, education, tooth brushing frequency, dental plaque, diabetes and alcohol use served as explanatory variables for the adjusted models. RESULTS Smoking intensity associated with tooth loss in an exposure-dependent manner: those with a high number of pack-years had a significantly greater probability of tooth loss than never smokers: 11-20 pack-years (RR = 1.55, 95 % CI = 1.15-2.08) and 21 or more pack-years (RR = 1.78, 95 % CI = 1.36-2.33). Smoking duration also associated with tooth loss: those who had smoked for several years had a significantly higher probability of tooth loss than never smokers: 21-30 years of smoking (RR = 1.66, 95 % CI = 1.29-2.12) and 31 or more years of smoking (RR = 1.72, 95 % CI = 1.20-2.45). CONCLUSIONS We found a clear intensity- and duration-dependent relation between smoking and tooth loss among adults with access to subsidized dental care and in good oral health.