Treatment with a growth factor-protein mixture inhibits formation of mineralized nodules in osteogenic cell cultures grown on titanium.

Despite wide clinical application, the efficacy of platelet-rich plasma (PRP) for repairing bone defects and enhancing osseointegration of metal implants is still subject of debate. This study aimed to evaluate the effects of a well-defined PRP-like mixture containing platelet-derived growth factor-BB, transforming growth factor (TGF)-beta1, TGF-beta2, albumin, fibronectin, and thrombospondin [growth factors (GFs) + proteins] on the development of the osteogenic phenotype on titanium (Ti) in vitro. Human alveolar bone-derived osteoblastic cells were subcultured on Ti discs and exposed during the first 7 days to osteogenic medium supplemented with GFs + proteins and to osteogenic medium alone thereafter up to 14 days. Control cultures were exposed to only osteogenic medium. Dose-response experiments were carried out using rat primary calvarial cells exposed to GFs + proteins and 1:10 or 1:100 dilutions of the mixture. Treated human-derived cell cultures exhibited a significantly higher number of cycling cells at days 1 and 4 and of total cells at days 4 and 7, significantly reduced alkaline phosphatase (ALP) activity at days 4, 7, and 10, and no Alizarin red-stained areas (calcium deposits) at day 14, indicating an impairment in osteoblast differentiation. Although the 1:10 and 1:100 dilutions of the mixture restored the proliferative activity of rat-derived osteogenic cells to control levels and promoted a significant increase in ALP activity at day 10 compared with GFs + proteins, mineralized nodule formation was only observed with the 1:100 dilution ( approximately 50% of the control). These results showed that a PRP-like protein mixture inhibits development of the osteogenic phenotype in both human and rat osteoblastic cell cultures grown on Ti.

Effects of the association between a calcium hydroxide paste and 0.4% chlorhexidine on the development of the osteogenic phenotype in vitro.

The present study aimed to evaluate whether the association between a calcium hydroxide paste (Calen paste) and 0.4% chlorhexidine (CHX) affects the development of the osteogenic phenotype in vitro. With rat calvarial osteogenic cell cultures, the following parameters were assayed: cell morphology and viability, alkaline phosphatase activity, total protein content, bone sialoprotein immunolocalization, and mineralized nodule formation. Comparisons were carried out by using the nonparametric Kruskal-Wallis test (level of significance, 5%). The results showed that the association between Calen paste and 0.4% CHX did not affect the development of the osteogenic phenotype. No significant changes were observed in terms of cell shape, cell viability, alkaline phosphatase activity, and the total amount of bone-like nodule formation among control, Calen, or Calen + CHX groups. The strategy to combine Ca(OH)(2) and CHX to promote a desirable synergistic antibacterial effect during endodontic treatment in vivo might not significantly affect osteoblastic cell biology.

In vitro osteogenesis on a microstructured titanium surface with additional submicron-scale topography.

The present study aimed to evaluate key parameters of in vitro osteogenesis on (1) commercially pure titanium (cpTi) discs with 20-200-microm-scale microtopography patterned with additional micron- and submicron-scale topography (0.5-20 microm; Plus surface, Dentsply Friadent), (2) control cpTi discs with 20-200-microm-scale microtopography (DPS, Deep Profile Surface, Dentsply Friadent), and (3) a machined surface. Using calvaria-derived osteogenic cultures, the following parameters were assessed: cell adhesion and spreading, growth curve and cell viability, alkaline phosphatase (ALP) activity and total protein content, immunolocalization of fibronectin, bone sialoprotein (BSP) and osteopontin (OPN), and bone-like tissue formation. The results showed no major differences between surfaces in terms of cell adhesion, growth curve, cell viability (days 4 and 11), ALP activity, or total protein content (days 11 and 17). At day 11, cultures grown on Plus exhibited small, well-defined nodular areas of calcified matrix, which were only rarely observed on DPS and absent on the machined surface. Such areas were larger at day 17 and were not associated with the typical mineralized bone-like nodules (with BSP- and OPN-positive osteoblastic cells on top). At day 17, the total mineralized area was significantly larger on DPS than on a Plus or machined surface (DPS>Plus>machined; Kruskal-Wallis test, P<0.05). Direct fluorescence allowed the straightforward observation of higher amounts of apoptotic bodies associated with mineralized nodules for Plus. The results suggested the occurrence of an additional, early pattern of matrix mineralization mostly for the Plus microstructured surface, which did not necessarily translate into larger bone-like tissue formation in vitro.