Considering the current status of clinical use of platelet concentrates in the fields of periodontology and oral surgery, in this study, we used 10-mL glass tubes that are not oxygen-permeable instead of oxygen-permeable plastic bags for storage of large volumes of WB or platelets. We advanced a working hypothesis that the storage of WB samples in glass tubes would result in a more rapid and substantial pH drop and inactivation of several enzymes involved in coagulation. This study revealed that addition of an optimal amount of a CaCl₂ solution successfully restored the coagulation ability of the anticoagulant-supplemented WB samples. The fibrin fibers prepared from the stored WB samples were almost identical to those of fresh WB samples. PDGF-BB concentrations were significantly lower in PRF extracts prepared from stored WB samples than in those of fresh WB samples. This effect can be explained by a growth factor release from platelets after stimulation by calcium ions or maybe (less likely) by degradation of PDGF-BB. Nonetheless, the bioactivities did not significantly worsen during the short storage.

In general, autologous platelet concentrates are prepared and immediately used for regenerative therapy in dental clinics at present. Our method should expand the clinical applicability of platelet concentrates, especially PRF preparations, and make the treatment schedule more flexible.