ABSTRACT
The effects of the filler composition on physical and mechanical properties of microfilled composites was investigated by measuring water absorption, solubility, compressive, flexural, and impact strength. A series of experimental composites, consisting of UDMA/TEGDMA comonomer matrix and prepolymerized fillers, was fabricated. The prepolymerized fillers were composed of hydrophobic colloidal silica and two monomers in varying ratios, trimethylolpropanetrimethacrylate (TMPT), and polyesterdiacrylate (PEDA). TMPT/PEDA ratios were 100:0, 64:36, 46:54, 18:82, and 0:100%. There were no significant differences in water sorption and solubility, regardless of the amount of PEDA monomer. Young's modulus and modulus of resilience increased with decreasing PEDA ratio. Fracture energy exhibited drastic changes (30.1 x 10(-5) J to 93.4 x 10(-5) J). The highest value of flexural strength (96.0 +/- 3.5 MPa) was obtained when the TMPT-PEDA filler was 46:54. The impact strengths of composites fabricated with TMPT-PEDA filler of 46:54 (11.2 +/- 1.4 kJ/m(2)), 18:82 (10.6 +/- 3.2 kJ/m(2)), and 0:100 (13.1 +/- 3.8 kJ/m(2)) were significantly higher than those with 100:0 (6.0 +/- 1.8 kJ/m(2)) or 64:36 (7.1 +/- 2.4 kJ/m(2)). Based upon the results, it was concluded that the mechanical properties of microfilled composites were improved by the modification of prepolymerized filler composition.
Subject(s)
Acrylates/chemistry , Biocompatible Materials/chemistry , Composite Resins/chemistry , Polyesters/chemistry , Polyethylene Glycols/chemistry , Polymethacrylic Acids/chemistry , Absorption , Dental Bonding , Dental Materials , Dental Stress Analysis , Hardness , Materials Testing , Methacrylates/chemistry , Models, Chemical , Polymers/chemistry , Resin Cements , Stress, Mechanical , Tensile StrengthABSTRACT
BACKGROUND: Massive hepatic necrosis from hepatic artery (HA) interruption is a complication after extended pancreatobiliary operation. The effectiveness of a mesenteric arterioportal shunt in preventing liver failure after massive hepatic necrosis was evaluated. METHODS: Of 98 patients who underwent pancreatic or hepatic resection for pancreatobiliary carcinoma between January 1989 and December 1995, six received a mesenteric arterioportal shunt. Clinical and hemodynamic analyses were done retrospectively. RESULTS: The six patients were classified into groups: A, postoperative hepatic arterial occlusion and, B, main HA excision without reconstruction. One patient in group A and three patients in group B had good arterioportal shunt patency and favorable clinical courses. However, fatal hepatic necrosis after ligation of the HA proper occurred in one patient in group A from small portal flow despite a presumed patent shunt. In another patient in group A angiogram revealed shunt occlusion. CONCLUSIONS: A mesenteric arterioportal shunt is beneficial when massive hepatic necrosis has occurred or is expected after main HA interruption under such conditions as postoperative hepatic arterial occlusion or HA excision without reconstruction. The procedure has the advantages of appropriate selection of artery size, a lower abdominal site apart from the primary operative field, and easy shunt closure by transarterial embolization.
Subject(s)
Arteriovenous Shunt, Surgical , Gallbladder Neoplasms/surgery , Hepatic Artery/surgery , Liver Neoplasms/surgery , Mesenteric Arteries/surgery , Pancreatic Neoplasms/surgery , Portal Vein/surgery , Aged , Female , Follow-Up Studies , Humans , Liver/pathology , Male , Middle Aged , Necrosis , Postoperative Complications/prevention & controlABSTRACT
We report a case of chronic gastric volvulus that was successfully treated by laparoscopic gastropexy. This procedure is also considered applicable to operations for other gastrointestinal disorders requiring organ fixation.
