Influence of plaque biofilm removal on reestablishment of the biocompatibility of contaminated titanium surfaces.

The aim of the present study was to evaluate the influence of plaque biofilm removal on the mitochondrial activity of human SaOs-2 osteoblasts grown on titanium surfaces. Volunteers wore acrylic splints with structured titanium discs for 72 h to build up plaque biofilms (n = 30). Specimens were randomly instrumented using either (1) an ultrasonic system at two power settings (EMS1, EMS2) + chlorhexidine (CHX), or (2) plastic curettes + CHX. Untreated (NC, n = 10) and sterile (C, n = 10) titanium discs served as controls. Specimens were incubated with SaOs-2 cells for 6 days. Treatment time (T), residual plaque biofilm (RPB)/clean implant surface areas (%), mitochondrial cell activity (MA) (counts/second), and cell morphology (SEM) were assessed. Statistical analysis revealed the following mean scores (+/-SD): RPB areas: P (58.5 +/- 4.9) > EMS1 (38.4 +/- 4.1) > EMS2 (28.3 +/- 2.0); T: PC (292 +/- 30) = EMS1 (244 +/- 24) > EMS2 (199 +/- 25); MA: C (1.544.661 +/- 203.442) > PC (597.559 +/- 566.984) = EMS2 (389.875 +/- 409.300) = EMS1 (356.653 +/- 293.863; n.s.) > NC (138.676 +/- 86.666). In NC and PC groups, cells were predominantly rounded in shape. However, in the EMS groups, some cells had started to spread, showing complete cytoplasmatic extensions of the cell body on the titanium surface. A monolayer of flattened cells was generally observed in the C group. Within the limits of the present study, it was concluded that MA seemed to be impaired by the presence of RPB areas. However, its removal alone might not be the crucial step in the reestablishment of the biocompatibility of titanium surfaces.