Levels of lipid peroxides and antioxidants in smokers and nonsmokers

The aim of the study was to evaluate the relationship between cigarette smoking and periodontal damage in terms of the levels of free radicals and antioxidants.

Thirty-five healthy subjects in the age group 25-56 yr and with chronic moderate inflammatory periodontal disease (attachment loss of 3-4 mm) were selected. All subjects were matched with respect to the clinical parameters plaque index, gingival index and attachment loss. Of the 35 subjects, 25 were smokers (smoking a minimum of 15 cigarettes/day) and 10 were nonsmokers. Smokers were subdivided into three subgroups: group I (10 subjects smoking 15-20 cigarettes/day); group II (10 subjects smoking 21-30 cigarettes/day) and group III (five subjects smoking > 50 cigarettes/day). Gingival tissue (obtained during Modified Widman surgery) and blood samples were collected from each of the subjects and analyzed for the following parameters: lipid peroxide, superoxide dismutase, catalase, glutathione and total thiol.

The level of lipid peroxide was lowest in nonsmokers (2.242 +/- 0.775 in tissue and 1.352 +/- 0.414 in blood) and highest in smokers smoking > 50 cigarettes/day (6.81 +/- 1.971 in tissue and 4.96 +/- 0.890 in blood), both in tissue and in blood. The increase was statistically significant in all groups, except in tissue of group I smokers. Catalase showed a similar trend, where the levels increased from 0.245 +/- 0.043 in controls to 0.610 +/- 0.076 in group III smokers for tissue, and from 0.231 +/- 0.040 in controls to 0.568 +/- 0.104 in group III smokers for blood. The increase was statistically significant for all groups. Total thiol levels were also higher in smokers than in controls (0.222 +/- 0.050 in controls vs. 0.480 +/- 0.072 in group III smokers in tissue; 0.297 +/- 0.078 in controls vs. 0.617 +/- 0.042 in group III smokers in blood). Except for group I in both tissue and blood, the increase was statistically significant. The superoxide dismutase (SOD) level was higher in nonsmokers (2.406 +/- 0.477 in tissue and 2.611 +/- 0.508 in blood) than in group III smokers (1.072 +/- 0.367 in tissue and 0.938 +/- 0.367 in blood), both in tissue and in blood, but this was significant only in the case of blood and for group III smokers in tissue. The glutathione level in tissue was consistently lower in smokers than in controls, showing a decrease from 121.208 +/- 37.367 in controls to 46.426 +/- 14.750 in group III smokers, but the decrease was not significant in group I smokers. In the case of blood, the glutathione level dropped from 262.074 +/- 68.751 in controls to 154.242 +/- 51.721 in group III smokers, but was statistically significant only for group III smokers.

The study results show that smoking increases the level of free radicals in periodontal tissues, which in turn may be responsible for the destruction seen in periodontal diseases.