Interaction between serum vitamin C levels and smoking on the periodontal condition in older adults

Background and Objectives Several epidemiological studies have reported that smokers have a higher prevalence and severity of periodontal disease than do nonsmokers, and that smoking negatively affects nutritional status and is associated with a reduced intake of antioxidants, particularly vitamin C. The present investigation aimed to examine the relationship between serum vitamin C levels and smoking and its influence on the periodontal condition in older adults. Materials and Methods A total of 353 respondents met the inclusion criteria and were enrolled in the present study. The periodontal status of the study participants was determined through examinations of one or more residual teeth, which included a measurement of the probing pocket depth (PPD) and clinical attachment level (CAL) at six regions of each tooth. Blood samples were collected during the dental examinations and then sent to a laboratory to evaluate serum vitamin C and cotinine levels. A serum cotinine concentration of 100 ng/ml was considered a relevant threshold for active smoking. After dividing the participants into two groups according to serum cotinine levels, Poisson regression analysis was carried out to compare vitamin C levels with the prevalence rate ratio (PRR) for periodontal condition markers for each group based on serum cotinine levels. Results We evaluated differences in the PRR of serum vitamin C tertiles between participants with high (≥100 ng/ml) or low (