Changes in gingivitis and protective factors among adults: A 4-year prospective population-based study

Objectives There are limited longitudinal data regarding gingival inflammation in adults. This study aimed to assess changes in gingivitis over 4 years and to determine protective factors. Methods A representative sample of 1023 adults living in Porto Alegre, Brazil, was obtained in the Caries-Perio Collaboration Study. At follow-up, 402 individuals were re-examined. Gingivitis was assessed by the gingival bleeding index (GB) at both time points. Individuals were dichotomized into those showing reductions >= 15% and those showing reductions < 15% or increase in bleeding sites. Multivariable Poisson regression models were fitted with 11 possible risk factors, estimating relative risks (RR) and 95% confidence intervals (95% CI). Results Percentage of individuals with GB >= 10% reduced from 72.4% to 53.8%. Bleeding sites significantly reduced (25.9%-20.1%), and in a higher magnitude in buccal/palatal sites (34.1%-24.0%). 31.0% of individuals presented GB reduction >= 15% in all sites. Toothbrushing >= 3 times/d increased 72% the probability of >= 15% GB reduction compared with <= 1/d (RR = 1.72; 95% CI 1.01-3.16). For each 10 pack-years smoked, the probability of >= 15% GB reduction was 3% higher (RR = 1.03; 95% CI: 1.01-1.04). At buccal/palatal sites, normal weight individuals had 26% higher probability of reducing GB than overweight-obese individuals (RR = 1.26; 95% CI: 1.01-1.62). A 5% higher decrease in GB sites was observed in the absence than the presence of periodontitis. Younger individuals had higher reduction in GB sites. Conclusions In the studied population, gingivitis reduced over time, with younger age, better oral hygiene, absence of periodontitis and normal weight being found to be protective factors. Smoking was associated with lower levels of gingivitis over time, probably due to its vasoconstrictive effect.