Journal of Biomaterials Applications

Although medical connectors compose very small parts of the extracorporeal circulation (ECC) systemthey represent a critical localization where early thromboembolic processes can manifest. In the present study we modified an in vitro closed-loop model with fresh human whole blood for the preclinical evaluation of the hemocompatibility of three types of medical connectors: non-coated (control); with silicone-, and heparin-coating. Each single loop consists of five polycarbonate connectors joined together by five pieces of silicone tubes. Thrombin-antithrombin-III, β-thromboglobulin (β-TG), PMN-Elastase, terminal complement complex, CD 11b expression, and surface-absorbed fibrinogen were measured. After 1 and 2 h recirculation, platelet loss, release of β-TG, and adsorption of fibrinogen were significantly higher (p<0.05) within the non-coated connectors compared to the silicone- and heparin-coated groups. Following this experiment, the connectors were filled again with fresh heparinized whole blood from the same donor to evaluate the influence of prior blood contact. Here, the activation of platelets and coagulation was dependent on the duration of the blood preincubation period.

Probably, the coated surfaces possess a reduced, or selective adsorption of plasma proteins, which in turn leads to a faster creation of a blood-friendly secondary superficial membrane, and prevents a further denaturation and hence activation of the adsorbed proteins.

Fracture strength of denture base resins is of great concern, and many approaches have been used to strengthen acrylic resin dentures. Fracture resistance of six commercially available acrylic resin denture base materials were compared, through impact and transverse strength tests. Three rapid heat-polymerised resins (QC 20, Meliodent and Trevalon), two high-impact strength resins (Trevalon Hi and Lucitone 199) and a strengthened injection-moulded acrylic resin (SR Ivocap plus) were included in the study. Twenty acrylic resin test specimens were fabricated from each resin. For impact strength test, ten notched specimens were tested in a Charpy-type impact tester. The other ten specimens were used for transverse strength tests, deflection and modulus of elasticity values were also determined, which were assessed with three-point bending tests using an Universal Testing Machine.

Impact test values showed significant differences among acrylic resins (F = 4.817 p = 0.0). SR Ivocap resin showed the highest impact strength values, followed by Trevalon Hi and Lucitone 199. The transverse strength test values were not significant when six acrylic resins were compared (F = 1.705 p = 0.151).

High-impact resins can be recommended to increase the impact strength of denture base. If the cause of fracture is mechanical or anatomical, strengthened acrylic resins and conventional acrylic resins have similar fracture resistance.

The aim of this research is the surface hardening of the ball-and-socket joint of dental implants by means of heat treatments in order to obtain titanium nitrides. These nitrides minimize the wear of the titanium used in prosthesis. In this paper the optimum heat treatment, the hardness and the wear resistance are described in relation to the ball-and-socket joint without heat treatment.

We evaluated the extent (luminal coverage) of the endothelial cell (EC) lining/neointimal development and the thromboresistance of electrostatically EC seeded small diameter Chrono Flex-polyurethane vascular grafts. The evaluation consisted of harvesting autologous, canine jugular vein ECs, electrostatically seeding the polyurethane grafts (4-mm I.D., length = 6 cm) with the harvested ECs, implanting the grafts in a canine femoral artery model for four to six weeks, and excising the grafts for histological and scanning electron microscopy evaluations.

Results of the histological evaluation (mid-graft region only) indicated that electrostatic EC seeding led to neointimal development and to minimal to no thrombus formation within the EC seeded grafts. The unseeded control grafts resulted in no neointimal development and substantial thrombus formation on the graft luminal surfaces. Scanning electron microscopy examination demonstrated a mature, confluent endothelium with a ‘‘cobblestone’’ appearance on the EC seeded graft luminal surface after six weeks.

We conclude that electrostatic EC seeding enhanced the development of a neointima and reduced the incidence of thrombosis in polyurethane grafts implanted in a canine femoral artery model.

Both autogenic and allogenic bone hasbeen employed through different surgical procedures to fill different defects or as osteosynthesis materials. Some physical and/or chemical treatments are usually necessary before its use. Since bone volume is important from a surgical point of view, the present study was designed to analyse its possible variations when subjected to certain procedures. Screws made of bovine cortical bone were autoclaved in different conditions regarding time and vacuum (A1–A2), cryopreserved, demineralised, enzymatically digested and rehydrated. The samples were measured before and after every treatment. Sterilisation caused a volume reduction more marked with method A1 than A2 whereasfreezing allowed to obtain the original size. No volumetric changes were registered after demineralisation and enzymatic digestion. Rehydration significantly increased their volume already during the first hour but the maximum value was reached at 24 h. Thus, autoclaving was the only treatment able to reduce the bone volume whilst freezing and rehydration allowed the samples to return to their original size.