Cytokine production and bone remodeling in patients wearing overdentures on oral implants

The stability of titanium dental implants is determined by osseointegration . Bone is a dynamic tissue continuously remodeled through resorption and fo rmation, processes controlled by local cytokine production. This study inve stigated osseotropic cytokine expression in gingival mucosa, in the intrafo ramina and inferior first molar zones, during rehabilitation with implant-r etained overdentures. Specimens were taken from six patients prior to place ment of implants in the intraforamina bone; at connection of healing abutme nts; and 4, 8, and 12 months after prosthetic anchorage. Through semi-quant itative reverse-transcriptase polymerase chain-reaction, the following cons titutively expressed cytokines were found at first surgical stage: interleu kin-1, -6, and -8; small amounts of interleukin-11; stem cell factor; and t ransforming growth factor-beta 1, -beta 2, and -beta 3. From the connection of healing abutments to 12 months after prosthetic anchorage, transforming growth factor-beta 1, -beta 2, and -beta 3 were markedly higher than initi al values. Expression of interleukin-6 and -8 decreased 8 months after pros thetic anchorage, while that of interleukin-l increased at 12 months. In cu ltured gingival fibroblasts, modulation of cytokine secretion was also time -dependent. Cell culture supernatants influenced osteoclast-like multinucle ated cell formation in long-term human marrow culture or osteoblast functio n, depending on the cytokine profile produced. These results are consistent with functional contributions of cytokines to osseointegration and minimiz ation of posterior edentulous zone bone resorption.