Features of free radical lipid peroxidation and serum proteins at dental implants and peri-implantitis

Aim. Determine the most informative indicators of free radical peroxidation in blood plasma for predicting the complications of dental implantation.

Methods. The study included 84 patients of both with dental implants, including 31 patients without any complications and 53 patients with peri-implantitis. The levels of lipid peroxidation products and protein carbonylation were measured in peripheral blood.

Results. Moderate intensification of lipid peroxidation and protein carbonylation was discovered in blood serum of patients with dental implants. Increased free radical oxidation in the blood was not limited to lipid peroxidation and resulted in increased serum levels of carbonylated proteins. Facilitation of oxidative degradation of proteins in the blood was associated with decreased resistance to «carbonyl stress», manifested as increased level of Fe+2/H2O2-induced carbonylation. Development of peri-implantitis resulted in a greater enhancement of free radical oxidation of blood. Isopropanol-soluble and heptane-soluble Schiff bases level was increased in blood serum as well. Similar to patients with dental implants, increased levels of carbonylated proteins was observed in blood serum at peri-implantitis. However, free radical oxidation was more intense in patients with peri-implantitis compared to patients with dental implants. Indeed, the level of heptane-soluble Schiff bases at the group with peri-implantitis was 2 times higher as compared to dental implants group, and the level of isopropanol-soluble lipid peroxidation products in inflammatory complications after implantation has reached fourfold increase compared with patients who underwent operation without complications.

Conclusion. Investigated indicators of free radical oxidation may be used as markers of peri-implantitis. Among them, the most informative indicators are Schiff bases and metal-catalyzed protein oxidation.