ABSTRACT
In the literature both smoking and psoriasis are discussed as predisposing factors for chronic periodontal disease. It is also known that smoking leads to deterioration in both psoriasis and periodontal disease. However, up to now, the only study to address the question what effect the co-occurrence of psoriasis and smoking has on the periodontal status of the individual, was a previous study of ours. In the present study, we repeated our measurements in an extended sample. 82 psoriatic patients and 117 controls participated, who all received a full-mouth examination so that their periodontal status could be determined. The analysis was aimed at finding out about to what extent the individual risk factors (i.e. smoking and psoriasis) increased the chance of the occurrence of the advanced stages of periodontal disease. The odds ratio for smoking was 1,32 (p = 0,465), and 1,85 for psoriasis (p = 0,163). In those patients who smoked, the odds ratio was 6,22 (p < 0,001), which is three times higher than the simple combination of odds. This suggests that the risk factors are in a synergistic relationship.