Peri-implant disease is considered to be an inflammatory disease, but many aspects of its pathogenesis remain unknown. At present, peri-implant disease is considered to be initiated and perpetuated by a small group of predominantly Gram-negative, anaerobic, or micro-aerophilic bacteria that colonize the subgingival area. Bacteria cause the observed tissue destruction directly by toxic products and indirectly by activating host defence systems, i.e. inflammation. A variety of molecular species appears in the inflamed tissues, among them are reactive species such as free radicals and reactive oxygen species (ROS). The purpose of this study was to assess levels of various antioxidants in saliva to identify differences between the saliva of patients with healthy peri-implant tissues and patients with peri-implant disease, and to examine whether the whole saliva of those with peri-implant disease conditions might have lower levels of antioxidants than that of healthy individuals. Thirty healthy adult volunteers (14 men and 16 women) with implant-supported overdentures (Ankylos((R)) Biofunctional Implants) were selected from the group of patients from Tallinn Dental Clinic. Biochemical and clinical parameters evaluated were the following ones: the levels of urate, ascorbate, myeloperoxidase in saliva, total antioxidant status of saliva, pocket probing depth (mm), gingival index (0, 1, 2, or 3), and bleeding on probing (0 or 1). Total antioxidant status (TAS) of saliva and concentration of uric acid and ascorbate, which are the main salivary antioxidants, are significantly decreased in patients with peri-implant disease. TAS in healthy subjects was 0.41 +/- 0.10 for resting saliva and 0.31 +/- 0.09 for stimulated saliva; in diseased subjects TAS was 0.19 +/- 0.07 and 0.12 +/- 0.03, respectively. In healthy subjects, the concentration of urate was 307.2 +/- 78.06 mu M/l in resting saliva and 241.5 +/- 89.09 mu M/l in stimulated saliva. In diseased patients, the concentration of urate was 120 +/- 36.13 and 91.60 +/- 39.35 mu M/l, respectively. The concentration of ascorbate did not differ in resting and stimulated saliva. In healthy subjects, it was 2.79 +/- 0.81 mg/l and in diseased subjects, it was 1.54 +/- 0.30 mg/l. This may indicate that excessive ROS production in peri-implant disease is leading to the situation of excessive oxidative stress, which may be an important factor contributing the destruction of peri-implant tissues. The importance of these findings may be the better understanding of the processes involved in the pathogenesis of peri-implant disease and that the treatment of peri-implant disease may involve adjuvant anti-oxidants supplementation together with cumulative interceptive supportive therapy concept introduced by Mombelli & Lang.
