Haemostasis in oral surgical procedures involving patients with a ventricular assist device.

The purpose of this study was to determine whether tooth extraction for patients with ventricular assist devices (VADs) could be performed without interruption of anticoagulant and/or antiplatelet therapy and whether treatment with von Willebrand factor concentrates and desmopressin is required. The study consisted of three groups of patients undergoing oral surgery. The two experimental groups comprised patients with VADs, while the third group included cardiovascular patients without VADs who served as controls. All patients were treated intraoperatively with topical haemostatic agents (oxidized cellulose or collagen). The first group was additionally treated with fibrin glue. All 75 oral surgical procedures were performed under local anaesthesia without sedation. Three of 40 patients in the experimental groups and two of 20 patients in the control group suffered a haemorrhage, with no significant difference in the incidence of haemorrhage between the groups. The findings suggest that dental extraction can be performed without modification of oral anticoagulation or antiplatelet treatments, providing that INR is less than 3.5 on the day of the operation. It can further be hypothesized that an acquired coagulopathy in VAD patients does not influence the bleeding risk in dental extractions, and so the administration of desmopressin and/or von Willebrand factor concentrates is not required.

Effect of bone sialoprotein and collagen coating on cell attachment to TICER and pure titanium implant surfaces.

To improve integration between implants and biological tissues, this study compared bone sialoprotein (BSP) as a surface-coating material against the major organic and inorganic components of bone, collagen type I and hydroxyapatite (TICER). The expression of osteocalcin, osteonectin and transforming growth factor ss was evaluated using immunohistochemical staining procedures. The distribution patterns of osteoblasts on the surface of pure titanium with a smooth machined surface and a rough surface (TICER) were determined by image processing using confocal laser scanning microscopy. The results compared to uncoated control materials showed that, at all times investigated, the number of cells on the surface of the TICER and pure titanium samples differed significantly (P<0.1), demonstrating the superiority of TICER over pure titanium in this respect. For pure titanium implants, collagen-precoated surfaces were not beneficial for the attachment of bone-derived cells with the exception of day 3 in vitro (P<0.01). BSP-precoated implant surfaces displayed non-significantly higher numbers of settled cells. BSP-precoated implant surfaces were beneficial for osteoinduction as revealed by osteocalcin and osteonectin expression. BSP precoating of the rough TICER implant surface enhanced the osteoinductive effect much more than did collagen precoating. These results contribute to the consideration of at least two distinct pathways of osseointegration.

Preparation and characterization of selenium incorporated anodic conversion coatings on titanium surfaces for biomedical applications.

An anodic spark deposition process was used for preparation of inorganic, glass-ceramic like conversion coatings. The microstructure of the layers was characterized by surface and solid state techniques such as scanning electron microscopy, electron probe microanalysis and Raman spectroscopy. The porous coatings, typically up to 8 mum thick, consist mainly of titanium oxides and amounts of incorporated electrolyte constituents like Se, Ca or P. Beside nano crystalline anatase phases, a mostly amorphous structure is proposed in which network-forming [PO(4)] tetrahedras and [TiO(6)] octahedras in various degrees of condensation are connected. A drastic modification of the film structure was observed when selenium was incorporated into the glassy oxide structure of the coating. In these cases no nano crystalline phases of titanium oxides or other chemical compounds were detected. First cell culture investigations show a significant improvement of the biological properties. Cell proliferation and TGF-beta-expression of these coatings in comparison with commercial pure titanium (CPT) with native titanium oxide films were examined.

Implant surface coatings with bone sialoprotein, collagen, and fibronectin and their effects on cells derived from human maxillar bone.

The interaction between implant material and surrounding tissues is believed to play a fundamental role in implant success. Although bone sialoprotein (BSP) has been found to be osteoinductive when coated onto femoral implants, collagen and fibronectin are the most used compounds for preparation of pre-coated cell culture slides at present. In this study, the support of BSP-, collagen- and fibronectin-coated and non-coated implant material for the development of adult human maxillar bone in vitro was studied and compared. The expression of bone turnover markers like BSP and osteocalcin as well as osteonectin, transforming growth factor beta (TGF-beta) and CD90 during different time periods of cell cultivation (3, 5, 10, 15, 20 and 25 days) was visualized immunohistochemically. The distribution patterns of the cells were examined on a rough surface of the titanium-hydroxyapatite dental implant material TICER and on a total smooth surface of the technical implant material glimmer. Significantly different values were found for glimmer at the 15. and the 20. Div, exclusively, indicating that a smooth surface was more improved than a rough ceramic surface by pre-coatings. The White-test using rankings of the median values gave evidence for BSP-coatings at position 1 followed by collagen. Our experiments were designed to use very low concentrated BSP coating solution with the aim to reduce the healing time with a minimal effort and minimal risks for the patients.