Methods: The posterior parts of the archwires were sectioned into 20 mm segments (N = 102) and divided among six groups. Four groups were treated with different pH levels and two served as controls. The specimens were immersed in individual test tubes containing 10 ml of artificial saliva adjusted to a pH of 6.75 or 3.5. The tubes were sealed and stored in a 37 °C water bath for 28 days. After 28 days, the specimens were ligated to brackets embedded in an acrylic block and subjected to mechanical stress using an electronic toothbrush for 210 s. The specimens were photographed, and images were measured for coating loss using AutoCAD® software. Surface morphology was observed using a scanning electron microscope (SEM).

MATERIALS AND METHODS: We report 20 consecutive patients with end-stage renal failure (ESRF) who had central vein occlusion and were not amenable to endovascular intervention. They underwent extra-anatomical vein to vein surgical bypass. The axillary and iliac or femoral veins were approached via infraclavicular and extraperitoneal groin incisions respectively. In all the patients, an externally supported 6 or 8 mm polytetrafluoroethylene (PTFE) graft was used as a conduit and was tunnelled extra-anatomical. All patients had double antiplatelet (Aspirin and Clopidogrel) therapy post-operatively.

RESULTS: Substantial improvement in the facial, neck and upper limb swelling was noticed following this diversion surgery. The vein to vein bypass was patent at 12 months in 10 out of 20 patients. Graft infection occurred in two (10%) cases. Re-thrombectomy or assisted patency procedure (stent/plasty) was done in four (20%) cases. The patients with preoperative fistula flow rate of more than 1500 ml/min and post-operative graft flow rate of more than a 1000 ml/min were patent at 12 months (P=0.025 and p=0.034 respectively).