OBJECTIVETo investigate the relationship between plasma levels of fibrinogen, the-beta455 G/A fibrinogen gene polymorphism and the severity of periodontal inflammation and to explore the possible role of fibrinogen in the association of periodontitis with coronary heart disease (CHD).

METHODSA total of 121 patients with moderate to severe periodontitis and periodontally healthy and gingivitis controls were enrolled in the study. Peripheral blood samples were collected and the plasma fibrinogen levels were determined by the clotting method of Clauss. Polymerase chain reaction and restriction fragment length polymorphism analysis with Hae III were used to examine the -beta455 G/A fibrinogen gene polymorphism.

RESULTSFibrinogen levels were significantly higher in moderately or severely chronic periodontitis patients [(3.45 +/- 0.68) g/L] than periodontally healthy and gingivitis controls [(2.47 +/- 0.42) g/L, P < 0.001]. The carrier status of the A allele at position -455 in the beta fibrinogen gene was associated with elevated fibrinogen levels and the frequency of the-A455 allele in the beta fibrinogen gene in the patient group was significantly higher than in the control group (P = 0.032). Carriers of the -A455 allele were about 3-fold more likely to have moderate or severe periodontitis as compare to individuals without the -A455 allele( OR = 3. =135, P= 0.008).

CONCLUSIONSFg-beta455 G/A polymorphism may contribute to the elevated plasma fibrinogen levels and put individuals at higher risk of having severe periodontitis. As the independent risk factor of CHD, fibrinogen levels and Fg-beta455 G/A polymorphism may play a role in the pathogenesis of periodontitis.