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Intraoral bone grafting is routinely employed for implant site development. Bone graft consolidation is a complex biologic process depending on the formation of blood vessels into the augmented area. Hypoxia-inducible factors (HIFs) and hypoxia-mimicking agents (HMAs) are key stimulators of blood vessel formation. Hypoxia prevents HIFs from degradation, thus signaling angiogenesis. Under normoxia, HMAs prevent degradation of HIFs. The cellular and molecular mechanisms responsible for angiogenic-osteogenic coupling and the therapeutic manipulation of HIFs and HMAs in intraoral bone repair and regeneration are discussed. Such discoveries suggest promising approaches for the development of novel therapies to improve intraoral bone repair and regeneration procedures. [ABSTRACT FROM AUTHOR]

Purpose: To compare in vitro the attachment and proliferation of human osteoblast-like cells (MG63) on tissue culture plates and guided bone regeneration (GBR) membranes in the absence or presence of nicotine. Materials and Methods: Membrane samples were fixed to wells and the cell number (CN) was counted after 24 hours (attachment assay) or 5 days (proliferation assay). The ratio of cell count (RCC) (CN at 5 days/CN at 24 hours) was calculated. The study had three parts: First, five different resorbable GBR membranes were compared (Resolut Adapt LT [RALT], Biocollagen [BC], Bio-Gide [BG], OsseoGuard [OG], and Demokritos Human Tissue Bank [DEM]). Next, cells were cultured on tissue culture plates with five different concentrations of nicotine. Finally, cells were cultured on the membrane that had demonstrated the highest RCC and CN in part 1 with four different concentrations of nicotine. Results: At 24 hours, BG showed the highest CN and OG showed the lowest CN. At 5 days, BG showed the highest CN. The order of RCC was BG > OG > DEM > RALT ~ BC. At 24 hours, lower nicotine concentrations (0.3 and 3 ?g/mL) showed higher CNs versus the control, whereas CNs for high nicotine concentrations (30 and 300 ?g/mL) were lower than for the control. CN at 5 days and RCC were lowest with 300 ?g/mL nicotine. At 24 hours and 5 days, all differences among wells with membrane were statistically insignificant. Nevertheless, CN at 5 days and RCC were highest with the lowest nicotine concentration (3 ?g/mL) and lowest with high concentrations. Conclusions: Membrane materials influence attachment and proliferation of bone cells and, therefore, could affect the outcomes of GBR. On both tissue culture plates and membranes, there is a tendency toward a biphasic effect of nicotine, with stimulatory effects at low concentrations and inhibitory effects at high concentrations. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to evaluate the gingival fibroblast proliferative response derived from patients with chronic and aggressive periodontitis to homologous platelet-rich plasma (PRP)., Materials and Methods: Gingival fibroblasts derived from nine patients with chronic periodontitis, aggressive periodontitis and healthy periodontium were grown. Medium was replaced with DMEM containing 0.5% FBS in which cells remained for two days. Cells were incubated and cultured with medium containing 50 microl/ml homologous platelet-rich plasma (PRP) or not containing PRP (control) for 24 and 48 hours. PRP originated from three donors. Cell proliferation effect was evaluated at 24 and 48 hours. Cell viability was assessed with a hemocytometer. Viable cells were counted under a phase contrast microscope., Results: The results revealed that incubation of human gingival fibroblasts, derived from healthy and intact periodontium, chronic periodontitis and aggressive periodontitis, in culture medium containing homologous PRP statistically significantly increased the cell proliferation at 24 and 48 hours of culture., Conclusion: The addition of PRP to human gingival fibroblast cultures significantly increased the proliferative response, irrespective of the presence of periodontitis, type of periodontitis and PRP donor.