Cellular fibronectin in failing dental implants.

PURPOSE Cellular fibronectin staining is decreased in adult periodontitis, which implies elastase-mediated degradation of periodontal tissues. The purpose of this study was to determine whether failing dental implants display similar changes. MATERIALS AND METHODS Cellular fibronectin and its integrin receptors were identified by immunohistochemistry and quantified by computerized image analysis. RESULTS Cellular fibronectin was found in blood vessel walls, epithelial basement membranes, and fibroblasts. Quantitative results of cellular fibronectin staining were as follows: failing dental implants, median 26.5% (Q3-Q1 = 23%); adult periodontitis, median 5.5% (Q3-Q1 = 5.6%); normal controls, median 12.2% (Q3-Q1 = 7.5%). Cellular fibronectin staining was increased around failing dental implants but decreased in adult periodontitis compared to healthy controls. DISCUSSION The distribution of integrin receptor subunits alpha4, alpha5, and beta1 of cellular fibronectin was similar in failing dental implants. The pathomechanisms in adult periodontitis and failing dental implants seem to differ. CONCLUSIONS Adult periodontitis is characterized by proteolysis/loss of cellular fibronectin, whereas failing dental implants are characterized by increased cellular fibronectin deposition, probably as a result of titanium-induced local synthesis and relatively modest degradation.